As a Construction Manager, what are your responsibilities with regards to the Civl Engineer and the Contractor. Discuss in detail your function, relationship and duties in all phases as described in class and chapter 14. This is a 2-page essay. Treat this as the catchall assignment where you are the CM on a land development project.

Practical Manual of Land Development This page intentionally left blank Practical Manual of Land Development Barbara C. Colley, P.E. Fourth Edition McGraw-Hill New York Chicago San Francisco Lisbon London Madrid Mexico City Milan New Delhi San Juan Seoul Singapore Sydney Toronto Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved. Manufactured in the United States of America. Except as permitted under the United States Copyright Act of 1976, no part of this publication may be reproduced or distributed in any form or by any means, or stored in a database or retrieval system, without the prior written permission of the publisher. 0-07-158897-3 The material in this eBook also appears in the print version of this title: 0-07-144866-7. All trademarks are trademarks of their respective owners. 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McGraw-Hill and its licensors do not warrant or guarantee that the functions contained in the work will meet your requirements or that its operation will be uninterrupted or error free. Neither McGraw-Hill nor its licensors shall be liable to you or anyone else for any inaccuracy, error or omission, regardless of cause, in the work or for any damages resulting therefrom. McGraw-Hill has no responsibility for the content of any information accessed through the work. Under no circumstances shall McGraw-Hill and/or its licensors be liable for any indirect, incidental, special, punitive, consequential or similar damages that result from the use of or inability to use the work, even if any of them has been advised of the possibility of such damages. This limitation of liability shall apply to any claim or cause whatsoever whether such claim or cause arises in contract, tort or otherwise. DOI: 10.1036/0071448667 Professional Want to learn more? We hope you enjoy this McGraw-Hill eBook! If you’d like more information about this book, its author, or related books and websites, please click here. To the young engineers who have been educated in the principles of engineering but not the day-to-day work of producing land development projects. To the working engineers who need a quick reference or checklist to expedite their work. To architects and developers who would like to understand why development engineers do the things they do. This page intentionally left blank For more information about this title, click here Contents Preface xv Acknowledgments xvii Chapter 1. Land Development Using This Book Nomenclature Local customs and resources Coordination Public Agencies The role of the public agent Dealing with public agents Public hearings The Developer Health issues and toxic substances Environmental issues Engineering Working in the metric system Numbers Computers Drawings and illustrations The Project Existing conditions Planning the project Criteria Setback requirements Timing Errors and omissions Summary Problems Resources Chapter 2. Resources Computers The internet Email 1 1 2 2 2 3 3 3 3 4 4 5 6 6 8 10 11 11 11 12 12 13 14 14 15 15 16 17 17 17 18 vii viii Contents Maps as Resources Aerial maps U.S. Geological Survey (USGS) maps and U.S. Coast and Geodetic Survey (USC&GS) maps Zoning maps Assessors’ parcel maps Geographic information systems Locating Land Title reports Property descriptions Coordinate systems Existing and proposed maps and plans Surveys Control surveys Boundary surveys Photogrammetry Topography Global positioning systems (GPS) Working with Computers Computer-aided design and drafting Spreadsheets Summary Problems Reference Resources Chapter 3. Site Analysis Zoning Considerations Getting Existing Plans Storm drains and sanitary sewers Signing, striping, and signalization Other utilities and services The Site Taking notes and photographs Recognizing signi?cant features Linear Projects Writing the Report Summary Problems Resources Chapter 4. Maps and Plans Maps as Tools Topographic maps Boundary maps Preliminary maps Tentative maps Record of Survey maps Parcel maps Lot line adjustments Subdivision and condominium maps Final maps ALTA maps Alternative route maps 18 19 19 19 24 27 27 27 28 33 37 38 38 38 38 40 40 41 41 42 43 43 44 44 45 47 47 47 48 48 49 49 49 53 54 55 55 56 57 57 58 60 60 61 61 61 61 64 64 64 64 Contents Elements of Plans The plan view Pro?les Cross sections Details Cover sheet Index sheet Plan sheets Types of Plans Master plans Demolition plans Grading plans Construction/improvement plans Traf?c plans Landscaping plans Utility trench plans Individual site plans As-built plans Summary Problems Resource Chapter 5. Preliminary Engineering Preliminary Design Preliminary Engineering Creating preliminary CADD drawings Maps Cost Estimating Clearing, grubbing, and demolition Grading Streets and highways Storm drains Sanitary sewers Water lines Other utilities Traf?c markings and safety features Factors Affecting Costs Miscellaneous costs and fees Fee estimates Contingencies Notes Summary Problems Resources ix 70 70 70 70 71 73 73 73 73 75 75 76 76 77 78 78 78 78 79 79 79 81 81 84 84 86 87 90 91 91 92 94 95 95 95 96 97 97 98 99 99 99 100 Chapter 6. Earthwork 101 The Geologic Report Landslides Groundwater Earthquakes The Soils Report Slopes Compaction Paving 101 101 102 102 103 104 106 106 x Contents Sources of Earthwork Unsuitable material Constructing the base Miscellaneous earthwork Shrinkage Designing Grading Plans Elevations Contours Cross sections Setting building pad elevations Linear Projects Adjacent property Determining Earthwork Quantities Determining shrinkage volumes Balancing the earthwork Contour grading Mass diagram Erosion, sediment, and dust The Grading Plan Summary Problems Resources Chapter 7. Roadways and Parking Lots Roadway Cross-Section Design Geometric cross sections Structural cross sections Curbs and gutters Superelevations Horizontal Alignment Establishing the reference line Stationing Horizontal sight distances Truck turns Vertical Alignment Designing the roadway pro?le Pro?le slopes Calculating the pro?le Meeting existing roadways Vertical sight distances Drainage Release Points Widening Existing Roadways Parking Lots Handicap parking and ramps Summary Problems Resources 106 106 107 107 108 109 109 111 112 112 115 115 115 115 117 118 118 120 121 124 125 126 127 127 127 128 129 129 130 131 131 137 137 137 138 139 139 144 145 145 148 149 152 153 153 154 Chapter 8. Sanitary Sewers 155 Sources and Quantities Sewage production The ?xture-unit method 155 155 158 Contents The peaking factor In?ltration The Sewer Network Laterals Horizontal location of the main Designing the pro?le Hydraulics The continuity equation Manning’s equation Calculating the pro?le Manholes and ?ushing inlets Pressure Systems Vacuum Systems On-Site Sewer Treatment Individual sites Decentralized sewage treatment Wetlands Summary Problems Resources Chapter 9. Storm Drainage Hydrology Storm water runoff Rainfall intensity Determination of the area Cross Drainage Surface Improvements and Structures Ditches Storm water inlets Manholes The Storm Drain Network Locating inlets Coordinating facilities Designing the storm drain pro?le Determining pipe sizes Technique for shallow sewers Outfalls Small individual sites Subterranean Water High water table Summary Problems Resources xi 158 160 160 160 162 163 165 165 167 169 176 176 177 177 178 178 180 181 181 182 183 183 184 185 187 190 192 193 197 197 198 199 200 201 204 205 206 207 207 208 208 208 209 Chapter 10. Protecting and Conserving Water Resources 211 Protecting Water Resources Parking lots over soils with good in?ltration characteristics Areas with poor in?ltration soils No more landscape mounds Detention ponds Construction sites 211 212 213 214 214 215 xii Contents Erosion Control Plans Recharge Facilities Wetlands Summary Problems Resources Chapter 11. Water Supply Lines Water Demand Industrial Nonindustrial Fire protection The Piping Network Reclaimed water system Back?ow prevention devices Horizontal layout The pro?le Appurtenances Gate valves Fire hydrants Thrust blocks Laterals and meters Summary Problems Resources Chapter 12. The Finished Plans, Speci?cations, and Estimates Managing CADD Company standards General standards Job ?le standards Improvement Plans Naming the ?les Layers Line types and fonts Setting Up the Drawings The standard sheets The title sheet Plan and pro?le sheets The plan view The pro?les Detail drawings Speci?cations Estimates Summary Problems Resources Chapter 13. The Construction Phase Contracts Quantities Spreadsheets 219 223 223 224 224 224 227 227 227 227 230 231 231 231 232 232 235 235 237 237 238 238 239 239 241 241 242 244 244 244 245 246 246 247 250 253 254 255 256 258 258 259 259 260 260 261 261 262 262 Contents Construction Scheduling The prebid and preconstruction meetings Construction troubleshooting Summary Problems Resources Chapter 14. Putting It All Together De?ning the Job The Contract Determining the fee Time pressure Coordination, Coordination, Coordination The Design Work Begins Simple residential or commercial site plans Subdivision maps Getting Started Sharing Job Files Architectural ?les Topographic ?les Preparing the Plans Site layout Grading and drainage Design of utilities Construction drawings Conditions of Approval Presentation Working with the Approving Agency xiii 263 263 265 265 266 266 266 267 267 268 269 271 272 273 273 274 278 278 279 280 280 281 282 283 284 285 286 286 Appendix A. Useful Websites 289 Appendix B. Conversion Table 293 Appendix C. Helpful Geometry and Trigonometry 295 Appendix D. Earthwork Calculation Example 297 Appendix E. Storm Drain System Calculation Examples 309 Glossary 317 Index 333 This page intentionally left blank Preface The objective of my book has always been to provide engineers and others working in land development with a quick, easy reference for day-to-day design problems and to introduce engineering students to the applications of their education. Some factors important to engineers and others in land development have changed significantly since the last publication. The importance of keeping the book relevant has prompted me to prepare this revision. Expanded use of the Internet for general information and reference material facilitates the design process. Where Web sites can be helpful during the process, they are added to the text. An appendix “Useful Websites” has been added to the back of the book for quick reference to facilitate research. Since the third edition of the Practical Manual of Land Development, protection of our water resources has become more important. The Clean Water Act of 1972 and its amendments have come to the forefront. Chapter 10 has been added to include various methods for protecting our water resources. That chapter includes requirements and design methods for implementing the National Pollution Discharge Elimination System (NPDES) and Storm Water Pollution Prevention Plans (SWPPP). Explanations to the requirements and examples and drawings related to the above issues are included in this edition. Because of the pressure of population growth, the use of central wastewater treatment plants has come into question. In some cases, it is more cost effective to construct community wastewater treatment with leach fields and treatment on-site than to provide sewers to transport effluent to a central processing facility. Chapter 8 has been expanded to present some of the options. Chapter 14 has been added describing step-by-step procedures for the land development process. Federal, state, and local governments are more involved every year. Engineering realities are seldom if ever taught in learning institutions. Much of the land development process involves laws, politics, and economics. They influence or even dictate the engineering approach. Also included in that chapter are procedures and methods for working with electronic files supplied by other consultants and ideas and hints for using CADD in a way that will facilitate the work. xv Copyright © 2005 by The McGraw-Hill Companies, Inc. Click here for terms of use. xvi Preface The expanded capabilities and increased use of computer-aided design for earthwork, profiles and utilities design has made some of the sections of the earlier editions to be no longer pertinent to land development designers. For that reason, the sections of the book involving those calculations are no longer necessary for understanding the design process. In an effort to keep the book relevant and easy to use, those sections have been changed to appendices and moved to the back of the book. They are therefore still available for training purposes and for engineers who are not yet using CAD to its fullest extent. Acknowledgments I wish to express my appreciation to Dave Hanson and Jennifer Costello of Carlile-Macy for generously giving their time and for providing the plans showing a development plan with detention ponds and wetlands replacement and restoration. They also provided the Erosion Control Plan for that project for which I am grateful. Pete Lescure of Lescure Engineers, Inc. has given his time and expertise about on-site sewage treatment facilities for this edition, which is greatly appreciated. Larry Hager of McGraw-Hill has been the editor for the last three revisions and has been very helpful. His suggestions and patience have greatly contributed to the success of these revisions. Thank you Larry. Barbara C. Colley xvii Copyright © 2005 by The McGraw-Hill Companies, Inc. Click here for terms of use. This page intentionally left blank Practical Manual of Land Development This page intentionally left blank Chapter 1 Land Development Making the environment more useful, safe, and comfortable for humanity is the purpose of civil engineering. Civil engineering for land development includes the design and construction of transportation corridors; flood control facilities; potable water supply facilities; collection and treatment facilities for solid and waterborne waste products; electrical, gas, and communications facilities; and buildings. Implementing the development and improvement of land involves political, economic, and esthetic considerations as well as engineering realities. A project may involve entrepreneurs, financiers, politicians, public agents, architects, landscape architects, geologists, hydrologists, environmentalists, biologists, and construction contractors as well as engineers. The skills and talents of land surveyors, mechanical engineers, fire safety engineers, and electrical and lighting engineers may be needed in addition to those of several kinds of civil engineers. Civil engineers specializing in traffic, structures, soils, and hydraulics may be needed. Effective communication among them is essential. Lack of clear communication can be the greatest obstacle to timely, satisfactory completion of any project. The intent of this book is to present a clear description of the tasks of the land development engineer and to promote a better understanding among the various people involved in land development. Using This Book The engineering design of public works and private projects should be done under the supervision of a highly educated, experienced engineer. This book has been written as an overview and guide to the engineering design of a variety of land development projects. The design of each aspect of the project must be made with an understanding and respect for the other aspects. The information found here is necessarily presented in a broad but shallow way. Readers desiring more depth of understanding should refer to the references at 1 Copyright © 2005 by The McGraw-Hill Companies, Inc. Click here for terms of use. 2 Chapter One the end of each chapter for further reading on the subject. Work through each of the examples presented in the chapters: The examples contain information about techniques and procedures that are not described in the text. By solving the problems in the examples, the text will become clearer and you will be more likely to retain the information. Reading and solving the problems at the end of each chapter will show you which information the author considers most important. Nomenclature Terms used to describe governing agencies, construction materials and techniques, and maps and plans vary in different parts of the country. The usage in this book should make the meaning clear. Great care has been taken to define terms and jargon when first used. However, if the meaning of a word used is not clear, refer to the glossary. The terms jurisdiction and agency are used frequently and interchangeably throughout this book. They refer to the political body that has power of approval over the aspect of the design being discussed. The jurisdiction may be anything from participants in a town meeting to representatives of the federal government. The terms pipe, line, conduit, main, sewer, and drain are also used interchangeably. The term developer can refer to a private party, a development company, or a public agency. Local customs and resources The words chosen to describe materials or procedures in this book may vary from the terms used for the same material or procedures in another part of the United States or another country. It is best to use what is customary locally unless there is clear evidence that some new terminology, material, or technique is superior. There are always those who resist change, and change initially requires additional time. Local agencies should be consulted for design criteria and specifications. When local agencies have not established criteria, nearby agencies with similar conditions and history or respected contractors working on the area can be helpful. This book is written as a guide only—as a set of rules. Coordination Each aspect of the improvement of any site must be coordinated with every other aspect. One may design the sanitary sewer with no problems, only to discover that its location creates a problem in the design of the storm drain. After both have been redesigned, it may be discovered that the new design creates a problem in a third area. The engineering may go smoothly, only to have the client or a public agent request redesign. The plans must be polished and polished again before they are finished. No subject or chapter in this book should be used without the others. Each chapter necessarily focuses on one aspect of the improvements, but all aspects are inextricably bound together. Land Development 3 Public Agencies Every project requires acquisition of permits from agencies charged with protecting the health and welfare of the public. These agencies have established certain criteria and standards. Ordinances have been written and established as law by political processes. Failure to obtain approvals may mean dismantling structures and/or financial penalties. It is right and necessary for public agents to examine plans and to require changes deemed necessary. The role of the public agent Public agents have a different perspective than the developer and engineer. They see not only the project but its impact on the immediate neighbors and the community at large. The region must be protected from disturbance of ecosystems. Air, noise, soil, and water pollution must be prevented. The agencies are responsible for verifying that the sewage transportation and treatment facilities are adequate, that the project is not situated where it will be endangered by floodwaters or landslides, and that planned storm drainage facilities will not increase storm water runoff. Further, most projects impact traffic flow patterns, requirements for fire and police protection, and school enrollment. These issues should be considered before a project is approved, while problems can be avoided or mitigated. Dealing with public agents It is important to establish a relationship of mutual cooperation and respect with public agents, whether they be the mayor of a metropolitan area or a file clerk in the county recorder’s office. We are dependent on these people for their approvals and assistance. File clerks may have more valuable information in their heads than all the files and computers in the office. File clerks who have been responsible for maps for many years can be worth their weight in gold. Very old maps and plans may be impossible to find without such people. The truism that contacts are essential to success is demonstrated daily in this business. Always introduce yourself to agents, and tell them whom you represent. Presentation of your card will help them remember you. Be courteous and respectful, and you will be remembered. Write down the names and positions of those you meet. Once acquaintance is established, even if just through telephone contact, information will be forthcoming more easily and quickly. If an agency plans to deny a permit for your project, ask about its concerns. Suggest solutions that meet those concerns and that satisfy the spirit and intent of the criteria. Public hearings Projects to be built with public funds, such as highways and airports, must be planned with notifications to and input from the general public. Public hearings must be scheduled and notification given to ensure the greatest participation 4 Chapter One by the public. At these meetings, the lead agency presents the plan, and private citizens and special-interest groups are given the opportunity to present their concerns and suggestions. The public meeting provides a forum for the engineers and other professionals to explain how these concerns are being addressed. Citizens may point out that a planned freeway will create a barrier between their children and the school their children attend. When this problem is brought to light, the need for a pedestrian overcrossing may be apparent. Other citizens may express concerns about noise and air pollution introduced by a new freeway. Experiences and comments from the public can be a valuable asset. Private projects are also subject to public hearings if they involve creation of new lots or changing existing zoning. Neighbors within a specified distance of the new project are notified of a planning commission, city council, or county board of supervisors’ meeting where they will have the opportunity to express their opinions about the project. If the project will change the character of the neighborhood or adversely affect some of the neighbors, ways are investigated and sometimes mandated to mitigate the potential problems. The Developer Each project is different from every other project. What is important to one developer may not be important to another. One developer, such as a state or federal agency, may study every detail and know exactly what materials and construction methods are to be used. Another developer may want to take the most economical approach possible. Know what approach the client wants. The most professionally designed project will not lead to further work from that client if the result is not what the client had in mind. Of course, if what the client wants would not be good engineering practice, the developer must be educated and directed to a more acceptable approach. Health issues and toxic substances Engineers and others have become increasingly concerned about toxic substances and their effects on people’s health. It has come to national attention that many of the practices of businesses and industries, as well as of ordinary citizens, have caused damage to the environment that will require years to repair. Asbestos was once a commonly used construction material. It is now known to cause lung and other cancers and is no longer used in construction. Asbestos used in ceiling tiles in many schools and public buildings is being removed with very tightly controlled methods to ensure workers’ safety. Underground storage tanks for gasoline and other toxic liquids have been installed without precautions against leakage. Not only are those tanks now being replaced with double-walled tanks, but soils testing and installation of monitoring wells to detect leaks are also being required. Determination of the extent of toxic plumes from previous installations and elaborate systems for monitoring wells are being required. Land Development 5 The previous use and purpose of property must now be known and evaluated before a construction project is undertaken. Liability created by previous owners may come with the property. If a piece of property was previously used for a gas station and there were leaks of gasoline into the soil, the new owner may be required to remove the toxic substances from the soil before any construction can begin. Materials stored on the property may also have adversely affected the soil and/or surrounding properties or waterways. Methods have been developed to treat some pollutants without extracting the soil (in situ treatment). New methods are being developed that utilize biochemistry and electrokinetic phenomena in soils. When underground pollution is widespread, this may be the only feasible way of correcting the damage. When extracting the pollutant from the soil is feasible, it can mean excavating the soil and dumping it in a Class 3 dump site. The cost of this approach is high, not only because the cost of removing and replacing the soil is expensive, but also because the fees for using a Class 3 dump site are high. Further, simply finding such a dump site may be difficult, and there may be a problem finding a contractor willing to take the risk of dealing with the toxic materials. The cost of cleaning a site can be so high as to make the property uneconomical to develop. If property is purchased without determining whether pollution is a factor, an unwary owner can be driven into bankruptcy. Environmental issues The environmental impact of land use and development has become a major factor for project planning. An environmental impact report (EIR) may be required locally, and an environmental impact statement (EIS) is required on most federal projects. Even on very small projects, some examination must be performed in order to qualify for a “negative declaration” stating that the project will not adversely impact the environment. A draft environmental impact report (DEIR) is prepared that addresses all the issues and ecosystems expected to be affected by a project. The draft report is then circulated through various governmental agencies, and the general public is given an opportunity to comment on and raise concerns that may have been missed by the report writer. Concerns of private citizens or political action committees (PACs) can cause a project to be altered or even terminated as a result of concern for such things as loss of habitat for an endangered species such as the spotted owl or a rare flower that grows only on the project site. Most often, mitigation can be provided to allow a project to go forward, but this does not always happen. The cost of the study in time and dollars must be factored in when a project is proposed. The disappearance of wetlands is an issue of major importance, as wetlands provide a unique environment for flora and fauna. In California, for instance, if wetlands are taken out of use because a highway bridge or some other structure will cover them, those wetlands must be replaced at a rate greater than 1:1 and can be as great as 7:1. The ratio is based 6 Chapter One on the quality of the proposed wetlands and the amount of time necessary for the new wetlands to become mature. Engineering There is a popular saying among civil engineers that when alligators are snapping at your ass, you forget that you set out to drain the swamp. Private-sector land development is one of the most time-sensitive of all businesses. The pressure to perform multiple tasks quickly can lead to oversights and errors. On any given day you may work on several different jobs. Interruptions for phone calls to solve minor problems or major crises on other jobs make continuity of thought on your primary task difficult. Keep in mind what you set out to do. There is considerable risk, particularly to young engineers, of overengineering simple problems. Construction of a retaining wall may solve a landslide problem, but removing the potential landslide material may cost less and make more sense. If a 0.1-m (4-in) plastic pipe will handle roof drainage adequately, do not install a 0.3-m (12-in) concrete pipe. Be alert to this risk, and check plans and results using common sense. Keep the work simple but complete. Whenever possible, solve the same problem more than one way and compare the results. It takes only minutes to superimpose two or more computer-aided design and drafting (CADD) layers or to lay one hardcopy over another on a light table to compare and look for differences. This simple process can quickly point out discrepancies and is well worth the time. Working in the metric system In 1991, the first President Bush signed an order that, beginning in October 1, 1996, all federally funded projects were to be designed and constructed using the metric system. This is the first step to promote conversion of all engineering and construction in the United States to metric. For that reason, this edition of the Practical Manual of Land Development has been written using the metric system. The traditional method of measuring and number usage in the United States is called the Imperial System. The International System of Units referred to as SI (from Le Système International d’unités) was adopted by the General Conference on Weights and Measures in 1960. It is the international system that is being universally adopted. The conventions used in this book are taken from three sources: 1. Standard for Use of the International System of Units (SI): The Modern Metric System, published as IEEE/ASTM SI 10-1997 2. Metric Practice Guide for Surveying and Mapping, by the American Congress on Surveying and Mapping 3. A-3 Metric Primer by CALTRANS (California Department of Transportation) A table of conversion factors (Table 1.1) follows, but it is not sufficient to know the conversion factors. There are a number of questions that arise concerning Land Development TABLE 1.1 7 Metric Conversion Factors LENGTH 1 mm = 0.03937 in 1 m = 1000 mm 1 m = 39.37 in 1 m = 3.281 ft 1 m = 1.094 yd 1 km = 1000 m 1 km = 0.6214 mi 1 in = 25.40 mm 1 in = 0.0254 m 1 ft = 0.3048 m 1 yd = 0.9144 m 1 mi = 1.609 km AREA 1 m2 = 10.76 sq. ft 1 m2 = 1.196 sq. yd 1 hectare (ha) = 10 000 m2 1 ha = 2.471 acres (ac) 1 sq. ft = 0.0929 m2 1 sq. yd = 0.8361 m2 VOLUME 3 1 m = 35.31 cu. ft 1 L = 0.2642 gal 1 m3 = 1.308 cu. yd 1 cu. ft = 0.02832 1 gal = 3.785 L 3 1 cu. yd = 0.7646 m MASS 1 kg = 2.205 lb 1 tonne = 1.102 ton 1 lb = 0.4536 kg 1 ton = 0.9072 tonne VELOCITY 1 m/s = 3.281 fps 1 km/h = 0.6214 mph 1 ft/s = 0.3048 m/s 1 mph = 1.6093 km/h FLOW TEMPERATURE 1 m3/s = 35.31 cfs °C = (°F − 32°)/1.80 1 cfs = 0.02832 m3/s °F = (1.80 × °C) = 32° 1 ac = 0.4047 how conversions are to be handled. For instance, if conversion factors are used exactly, a 12 ft wide traffic lane would become a lane 3.6576 m wide. This type of usage is referred to as “soft” conversion. It makes more sense to make the conversion to a more useful and suitable number. When we convert to a suitable number it is called a “hard” conversion. For a 12-ft lane converted to metric, CALTRANS uses 3.6 m. An 11-ft lane is converted to 3.3 m and a 10-ft lane is converted to 3.0 m. Dimensions 3.6, 3.3, and 3.0 m are equivalent to 12, 11, and 10 ft lane widths so that they meet the requirements for safety as well as the more precise number, and they are easier to use. You will want to use “hard” conversions for most of the work you will be doing in land development. Some commercial products such as sizes of lumber are described in a way that we understand what is meant even though the description cannot be taken literally. A 2 × 4 is understood to be lumber that is approximately 2 × 4 in but in fact that is the rough sawn size and the finished size is smaller. These kinds of items will retain their description and the size is referred to as the nominal size. Linear measurement is based on the meter (39.37 in) in the metric system. This degree of precision is sufficient for most calculations. However, in some instances such as in conversion of existing surveying information in imperial units where seven or more significant figures are required to satisfy the necessary precision, the information should be converted by multiplying the Imperial distance by 1200/3937. All distances should be shown in meters, kilometers (1000 m), or millimeters (0.001 m). Centimeter (0.01 m) is not used. Convention is to use the symbols for 8 Chapter One these dimensions, not abbreviations. The symbols are meters (m), kilometers (km), and millimeters (mm). Plurals are not shown. The symbols are always shown in vertical text regardless of surrounding text and in lower case and are not followed by a period. Further the symbol is to be separated from the number by one space such as 36 mm, not 36mm. The choice of whether to use meter, kilometer, or millimeter should be made so that the numerical value will be between 0.1 and 1000. Values smaller than a meter should be shown as millimeters. The exception to this is where the numbers are in a table. In that case, the values should all be in the same metric dimension. Do not mix unit names and unit symbols. Where you use a modifier, place it before the dimension as square meters or cubic meters. Areas are based on the metric system. Large areas will be in square kilome2 ters or, where we would traditionally use acreage, in hectares (10 000 m = 1 ha). The symbol “ha” is used for hectares. Angular measurements for civil engineering are expressed in degrees, minutes, and seconds or as degrees and decimals of a degree as in the Imperial System. Other SI applications use the radian (rad), which is the angle subtended by an arc of the circle equal to the radius. Time is expressed in seconds, minutes, and days as in the Imperial System. Velocity is expressed as meters per second (1 m/s = 3.281 fps) or kilometers per hour (1 km/h = 0.6214 mph). Flow is expressed as cubic meters per second (1 m3/s = 35.31 cfs). Gallons per hour or day is not used. Instead use m3/s or L/s where L is the symbol for liters. Here the symbol is capitalized, which is an exception to the rule of using lowercase letters. This is because of the likelihood that the lower case L (l) is easily confused with a 1 (one). The other exception is where the symbol is taken from a proper name as Watt (W). Decimal markers are shown with a period in the United States. A comma is used in some countries. For that reason, commas should not be used to set off large numbers into groups of three. Instead, a space is inserted after each set of three numbers as 1 000 000 or 0.000 001. When there are just four digits, no space is used as 4300 or 0.0043. Numbers Two words that engineers should have a clear understanding of are accuracy and precision. Accuracy refers to correctness. An answer is accurate (correct) or it is wrong. Precision is a matter of degree. An accurate measurement of 10 m does not tell you the degree of precision. The number 10.01 m is precise to within 10 mm. The measurement is greater than 10.00 m but not as great as 10.02 m. If a more precise measurement is needed, the measurement must be made to within 1 mm or 0.1 mm and so on. A number can be accurate and not be precise. An accurate value of a slope for drainage purposes of 1 percent may be just as useful as the more precise value of 1.03 percent. But a number that is not accurate, though it may be precise, is worthless. Land Development 9 Your work must always be accurate. The degree of precision you select should be based on what is dictated by the jurisdiction, the client, or common sense. If you are designing a grading plan, ordinarily 20 mm (0.81 in) is sufficiently precise. The contractor will not be able to construct it closer. For dimensions and elevations of structures, use 10 mm (0.40 in). The degree of precision that can be accomplished may be plus or minus 5 mm (0.2 in), but do not round off or the precision will be 5 mm plus the amount rounded off. Surveying property lines and preparing subdivision maps require more precision. The degree of precision depends on the size of the parcel being surveyed. When measuring angles, 1 degree of difference results in 17.452 m (57.25 ft) of offset difference for every kilometer of length; 1 minute of difference yields 0.29 m (0.95 ft) of offset difference for every kilometer; 1 second of difference yields 0.0484 m (0.156 ft) of offset difference for every kilometer. The degree of precision chosen should be based on the distance measured and the precision required for the finished traverse. In mathematical calculations, there is no advantage in using one value in a formula that is more precise than another value. The degree of precision of the answer cannot exceed the degree of precision of the least precise value in the equation. For example, where the circumference of a circle (C = pd) is needed and the diameter is given as 50.25 m, there is no point in using more than four significant figures for the value of p. Use 3.14 rather than 3.14159265. A value in a formula may be precise to two places to the right of the decimal even though no numbers are shown. For example, the value of 2 may be exactly 2, and the precision then is whatever is required, such as 2.00. Keep this in mind when selecting numbers to use in making calculations. When making conversions, determine the required precision as a guide as to how many digits to retain in the number to be converted. The converted dimension should be rounded to a minimum number of significant digits to retain required precision. If the value is preceded by “not more than,” the number should be rounded down. When you prepare estimates, the quantities should be rounded off to no less 2 than 5 m or 1 m . If the estimate is for a large project, the quantities should be rounded even further. Using more than four or five significant figures when making an estimate, which will total millions of dollars, is inappropriate and misleading. When design is complete, quantities can be determined exactly. The exact length of curb and square meters of paving will be known and should be used. However, showing values more precise than even meters is meaningless. Order of magnitude is a term that is frequently heard in engineering. The term refers to the relative size of a number. Checking that the order of magnitude of an answer is correct is particularly important when using computers because use of computers makes the work more abstract. When you have calculated an answer, check if the order of magnitude seems correct. For instance if you multiply 50 × 20 × 1, your answer should be 1000. If the answer comes out closer to 10 or 10 000 it is clearly wrong—it is the wrong order-of-magnitude. 10 Chapter One One technique that will aid in making correct calculations is always to show the dimensions of the numbers being used. Including the dimensions ensures that all the necessary conversion factors have been included. The dimensions must be calculated as well as the numbers. Meters times meters yields square meters—area. Square meters times meters yields cubic meters—volume. If the dimension of your answer is meters to the fourth power, it is wrong, since meters to the fourth power is physically meaningless. A clear demonstration of this approach is in use of the rational formula in SI. The rational formula is Q = CIA. It was developed in the Imperial System. The dimension for Q is cubic feet per second (cfs), C is dimensionless, I is given in inches per hour, and A is given in acres. However, in SI, we want Q to be in cubic meters per second, I in millimeters per hour, and A in square kilometers. If you label each value with the correct dimensions, the formula yields the formula in SI with Q in cubic meters per second. Q = CIA ? in. h 0.0254 m ? ? 4047 m2 ? =C ×? × × × ? ac × ? in. ac ?? ? h 3600 s ? ? = 0.0286 m3/s In the equation, inches, hours, and acres in the numerator cancels out inches, hours, and acres in the denominator leaving m3/s. Computers Use of CADD is now commonplace in civil engineering design and land development. Use of computers and state-of-the-art software to calculate complex formulas and manipulate large volumes of numbers has become necessary for designers to remain competitive. Once computer skills have been mastered, complicated computations can be made more easily, more quickly, and with less risk of error. Another advantage of CADD is that several similar alternatives can be designed with relative ease. There are programs designed to make exhaustive calculations for several alternatives to determine the best alternative relative to some aspect of the design, such as volume of earthwork. Determining what criteria or aspect of the design to examine is the challenging choice that no computer can make. The information the computer can provide allows the engineer to make decisions that maximize resources and meet the client’s needs more precisely. It is particularly important that the engineering designer have a clear understanding of the basics of engineering when using computers to solve engineering problems. Each problem is unique. The logic and reasoning is done by the engineer; the computer simply responds to the engineer’s direction to perform mathematical calculations or delineate lines. Engineers should develop expertise with engineering tasks before designing with computers. Inexperienced engineers using computers without a sound engineering background may be left Land Development 11 wondering if what they are doing is really correct—or worse, they may think they know what they are doing when in fact they do not. Some engineering college graduates enter the field thinking that because they can operate the computer software programs designed to facilitate the engineering design, they are doing engineering. That is not the case. A beautiful computer-generated set of plans can be deceiving. If consideration of the effect of such things as overland flows during flooding or provision of the access route to satisfy the Americans with Disabilities Act and if strict adherence to the “Conditions of Approval” are not met, the plans do not satisfy the purpose of the engineering. When they start using the computer before they have experience with engineering design, it slows their training and will set them back in their career goals. Some companies require 6 months or a year of experience before the computer can be used so that the engineers will have a better understanding of the design process. Colleges educate their engineering students in the elements of engineering but the overview and day to day skill are seldom taught. Even when they are, day-to-day experience is needed for a real understanding. This book provides the day-to-day instruction that will facilitate the learning process. In some companies, it is required reading. Drawings and illustrations Drawings and illustrations are important tools for engineers. They put the design concept into a tangible form. And a drawing made to scale is sometimes the fastest way to find the answer to a problem. Scale drawings are illustrated throughout this book. When there is an error in a traverse, plotting the coordinate points and connecting them can make the location of the error apparent. Plotting the points of a profile at a vertical scale 10 times as large as the horizontal scale clearly shows the location of any points that do not fit in a straight line or along a smooth curve. When using illustrations for members of planning commissions, city councils, and the general public, remember, they will not be familiar with drawings made using exaggerated scales. Such drawings may confuse them and cause negative feelings about what you are trying to illustrate. Use such drawings only if they are absolutely necessary, then precede and follow them with drawings of the same situation drawn at a natural scale, where the horizontal and vertical scales are the same. Even better, illustrate the design or problem with a scale model or generate the idea in four dimensions—the fourth dimension being time. Software programs are available to make these illustrations. The Project Existing conditions It is essential that the project engineer visit the site as early as possible. Each person visiting a site sees different things. It may be necessary to visit the site many times as the design progresses. Never accept the elevations and locations 12 Chapter One of significant existing structures from previously prepared plans without having a survey crew field—check the information. If the topography is not checked, differences may become apparent during construction, and the cost of redesign or reconstruction at that late stage is not worth the risk. Planning the project Planning the overall schedule for the project before the work begins is essential. The first step is determination of the design critical paths—those aspects of the design on which other aspects of the work depend. Doing a perfect job on one branch of a project, only to discover that essential information is not available and cannot be prepared in time to meet schedules, can be disastrous (Fig. 1.1). Criteria The criteria established by the various jurisdictional agencies must be followed. They may be documented in several ways, including city and county ordinances, and standard plans and specifications. During the approval process, each agency involved can stipulate conditions of approval. The client will have criteria, and your employer may have established criteria in the form of company policies. Other consultants, architects, traffic engineers, soils engineers, and environmentalists impose criteria as well. All these criteria should be kept in mind. A list should be made and checked frequently. For all projects, there are many criteria that affect the design. Some of the criteria, whether they be schedules, clearances, or some other value, cannot be changed and must be adhered to. These criteria are called critical points. Other Figure 1.1 Job schedule. Land Development 13 criteria will not be absolute. All critical points must be identified before the work is begun. In most cases, all the criteria can be met, but it is important to identify the critical points and give them priority during design. Setback requirements Planning criteria affects all sites. The architect or planner will have plotted the structures on a drawing of the property taken from the deed or from existing right-of-way or subdivision maps. Whether the new construction is residential, commercial-industrial, or a transportation corridor, there will be minimum distances required between the structures and property lines. Highways and other linear structures have minimum clearances to right-of-way lines and/or other structures. Whether those criteria are met can only be determined with careful calculations. Planners and architects present their drawings with scaled distances. Engineers and surveyors, however, cannot accept that information. The information must be checked mathematically. A current title report must be acquired from a title insurance company. The title report provides the grant deed, which is the legal description of the property purchased and lists any property or rights that may have been sold or otherwise granted after the original sale. The title report will provide a legal description of any piece of property that may have been sold from the original purchase, any easements over the property, or any easements attached to the property. Further, the title report will describe other parties who hold interest in the property such as property taxes due, mortgages, and liens. When the deed is analyzed by the surveyor and a field investigation of the boundary is completed, the distances and bearings may be different from those on the deed. When the true property line is thus established, the distances between structures and the property line may be less than expected and/or is required for setbacks. When this happens, the client and/or architect should be informed immediately, as the design of the structure will have to be altered to comply with the setback requirements. Easements are rights of limited usage held by one owner over the property of another owner. The most common easements grant a strip of land for vehicular access or for utility lines and their maintenance. Storm drain easements also are not unusual. Engineers must plot the easements that affect the site, and read the intent and restrictions imposed by them. Clearance of easements must also be verified by coordinate calculations. Overhangs and paved areas may be described separately, with separate setbacks to be used. Lot and building sizes and alignment of linear projects are sometimes determined by setback requirements. If several different house plans are designed for a particular subdivision, the engineer may be asked to prepare a “fit list” of which house plans fit which lots. On lots where the fit is questionable, the clearances must be calculated. The setback distances on all projects should be calculated at all critical points. 14 Chapter One Timing The statement “time is money” was never more true than in the land development business. When the economy is booming, land development and construction are booming. The faster the projects can be built, the more the money that can be made. When economic growth is slow, many developers are forced out of business. In fast-growing areas, the political and financial situation can change quickly. The various fees for building permits or sewer connections can be doubled or tripled with very little warning. Building moratoriums prohibiting further development can be imposed at any time. In most areas, wet or cold weather limits the months suitable for construction. Further, projects are usually financed and interest costs can be thousands of dollars a day. These are only some of the reasons why developers often expect the engineering design to be done quickly. Do not let the time constraints cause you to be careless or to leave out important checking. Ideally, the topographic and boundary surveys will be complete before the tentative map is drawn, and the tentative map approvals will be complete before the parcel or final maps are begun. Sometimes, however, all these processes are started as soon as the contract is signed. The planners start drawing a tentative map from the deed. The surveyors are sent into the field to collect boundary and topographic information, calculations are started for the final map and drafters begin work on base maps for the engineering design. Once these tasks are underway, the engineers and surveyors gather information on the design of existing and proposed utilities in the area. A visit to the site is essential for the engineer to spot potential trouble spots in the topography. Though an estimate of the existing elevations may be made from previous projects in the area, the topography of adjacent projects, or U.S. Geological Survey maps to start the process, careful, thorough field surveys will have to take place before engineering can begin. Existing streets and utilities are seldom constructed exactly as designed. As-built plans often are not representative of elevations and locations. The conditions for approval of the tentative map may require facilities that have not been planned for, and field investigation of the boundary may reveal that there is less available land than is needed. The true topography may be quite different than was anticipated. These differences must be corrected on the plans, adjustments made, and the deadline still met. Whenever changes are made, the potential for errors is greatly increased. Utmost care must be exercised to follow through on every aspect of the design that is affected by changes. Errors and omissions Delays during construction to solve engineering problems are very costly. Equipment and personnel standing idle while the problem is solved can cost thousands of dollars per hour. Removal and replacement of new structures may be the only solution to a problem that becomes apparent during construction. Thoroughness in researching existing and proposed facilities is essential. Often when design is in progress for one project, design may also be in progress for an adjacent or nearby property. Remember to ask public agents about other Land Development 15 projects that may be planned in the area. Their design and state of completion may affect your project. If the engineer’s oversight costs the clients money, you can be sure that they will look elsewhere for an engineer for their next project, or they will look to this engineer for compensation. Summary Civil engineering design and land development can be very complex and involve a wide variety of professional people and others. Engineers must understand and work well with the public and public agencies. Clear communication among the participants is essential. There are many resources available to assist the engineer. The engineer must know how to use those resources wisely. Ultimately, the civil engineering design is a product of those resources and the engineers’ experience and sense of logic. Planning the project based on schedules and interdependence of the various aspects of the design is a necessary first step. Problems 1. What is the greatest obstacle to successful completion of a design project? 2. Name five types of professionals involved in land development. 3. Name three kinds of civil engineers involved in land development. 4. Define jurisdiction. 5. When the local jurisdiction has no established criteria for some aspect of the work, what criteria should be used? 6. What is the task of the public agent? 7. What is the purpose of a public hearing? 8. What is the economic impact of a site having been used for toxic or hazardous material storage? 9. What is an EIS? 10. Describe an engineering problem and propose two solutions—one complex and one simple. 11. Convert the following values from the Imperial System to SI: a. 35.67 lf b. 47 mi c. 12.22 cy d. 22 ac e. 27.4 cfs 16 Chapter One 12. What is the difference between accuracy and precision? 13. Define order of magnitude. 14. Why is it important to use dimensions when solving engineering problems? 15. What is a critical path? 16. What is a critical point? 17. Name three sources of criteria for a project. 18. What is a title report? How is it used? 19. Define easement. Resources American Congress on Surveying and Mapping, Metric Practice Guide for Surveying and Mapping, 1978, 5411 Grosvenor Lane, Ste. 100 Bethesda, MD 20814. California Department of Transportation, A-3 Metric Primer, The Metric System. IEEE.ASTM SI 10-1997, Standard for Use of the International System of Units (SI): The Modern Metric System, Institute of Electrical and Electronic Engineers, New York, NY; ASTM, West Conshohocken, PA. Chapter 2 Resources This chapter describes the types of maps, plans, land surveys, software, and other resources available to civil engineering designers and others involved in land development. Computers During the 1980s, advancements in the development of computers and computer software revolutionized the civil engineering profession. Computer systems capable of integrating all aspects of civil engineering design and presenting it in four dimensions (the fourth dimension being time) are now available at a reasonable cost. Even small design firms using personal computers (PCs) can perform most of the same functions and have the work translated into a format that is usable with mainframe systems. The use of computer-aided design and drafting (CADD) systems and other software is included in each chapter where it can be applied. Installation of navigation satellites (Navstar) encircling the earth has provided a resource now taken for granted. With these satellites and the right receivers, travelers can determine their location anywhere on earth. Receivers are beginning to become commonplace in ordinary automobiles that can show your location as your vehicle moves through an area shown on a map. These satellites, used with the right system of receivers, can allow surveyors to locate property and topography on the x, y, and z axes to the degree of precision desired without line of sight and in any kind of weather. This capability can reduce the cost of surveying to a fraction of what it was a few years ago. This method of surveying uses global positioning systems (GPS). The Internet The increased use of the Internet in our lives in recent years is phenomenal. What it will mean to civil design engineers and land developers is just beginning to be revealed. Public agencies and commercial enterprises are providing 17 Copyright © 2005 by The McGraw-Hill Companies, Inc. Click here for terms of use. 18 Chapter Two information “on line” for design and construction. From those resources, information such as product specifications, plan specifications, and a wide range of other information can be downloaded. Some cities, counties, and states have posted forms, requirements, standard plans, and specifications on web sites. Not only are they convenient to access but, perhaps more importantly, they are constantly updated. These resources are increasing every day. Further, the Internet provides a way that engineers can share information through e-mail and e-mail attachments. Moving large electronic files from one computer system or Internet location to another computer system with broadband connections can be done in seconds. Projects can be put together between teams of consultants in far flung parts of the country or the world. The developer may be in New York, the civil engineer in San Francisco, the landscape architect in Colorado and the mechanical engineer in Texas. A project can be completed successfully without the team members ever meeting face to face. Email Asking for information or answers to questions with email can be especially efficient. The time “playing phone tag” can be eliminated while the participants get and answer emails when convenient and without disruption of their work. Further it is easy to keep track not only of information shared but the times when it was shared making it difficult for using lack of communication as an excuse for not making timely use of the information. A word of caution needs to be expressed here. Using email to communicate has its hazards. What is perhaps an even greater hazard is the lack of face-toface or even voice recognition in use of emails. Taking clues from body language and facial expressions are clues of which we are seldom aware but aspects of which do affect our interpretation of what is being said. The common expressions used when calling such as “How are you?” aren’t usually made on emails so emails can seem down right cold or even hostile. Worse is when someone is angry or frustrated when putting together an email. Once you hit that “send” icon there is no taking it back. Get away from the computer when emotions are running high. Type a message in then but it into a “drafts” folder or print it and delete it until you can be more objective. Better yet, don’t use the computer to express your anger. Use an old fashioned pencil and paper. That way the angry message cannot be “accidentally” sent. Maps as Resources Drawings that show the relative locations of various aspects of the physical and legal environment are called maps. Maps are usually two-dimensional and show only horizontal relationships. Relief maps are the exception and are threedimensional, showing the highs and lows of the ground level. Computergenerated images of relief maps can be useful in some situations but only two-dimensional maps will be discussed in this book. Topographic and aerial Resources 19 maps show physical environments. Topography is included on some of the other maps discussed in this chapter. Parcel maps and subdivision maps serve as legal documents and show unique parcels of land with mathematical exactness and to the exclusion of all other property. Information shown must be such that the location of the property lines is indisputable. Modern land development would be impossible without maps. Street maps, aerial maps, assessors’ parcel maps, zoning maps, flood-zone insurance maps, fault zone maps, enterprise zone maps, U.S. Geological Survey (USGS) maps, U.S. Coast and Geodetic Survey (USC&GS) maps, hazardous materials zone maps, and assessment district maps are some of the kinds of maps used by engineers involved in land development. Some of these maps are now available on compact disk or on the internet for designers to install into their computer systems to facilitate their use. Aerial maps Aerial photographs are particularly useful in the planning stages of projects. A single photograph may cover a very large area, or a series of photographs can be used to cover linear projects such as highways and canals. The engineer can see the entire area under consideration and can then better select alternative routes for a highway or a site for a development. The engineer then uses this information to locate the project where it can be built with the least disturbance to the existing conditions—and thus the least cost. These maps are also useful when making public presentations, as they provide information that the general public understands. Aerial photographs—either alone or with a profile grid—are sometimes reproduced and made available as an email attachment or on compact disk for use as a base for design. Photographs can also be digitized for use in computer systems. U.S. Geological Survey (USGS) maps and U.S. Coast and Geodetic Survey (USC&GS) maps USGS and USC&GS maps can be very useful in the early stages of research for a project. These maps are topographic maps showing large areas (Fig. 2.1). Because of the scale, only the general topography can be shown. That is, areas may be shown as occupied generally by buildings or orchards or open fields. Other information, such as the existence of a well on the site, may also be shown. In areas of rapid growth this information may be quickly outdated, so the engineer should determine when the map was prepared. The maps show contours typically at 40-ft intervals, which should not have changed significantly over time. In lieu of more specific information, these maps can be useful. Zoning maps The purpose of zoning maps is to show zoning districts (Fig. 2.2). These districts are used to control population densities and the character of growth. The intent 20 Figure 2.1 U.S. Geological Survey map. 21 22 Chapter Two Figure 2.2 Zoning Map. (Courtesy of the city San Jose, California) Resources 23 24 Chapter Two is to have compatible land uses adjacent and incompatible uses separate. Generally, the types of zones are industrial, commercial, business and professional, and residential. The zones are further subdivided to define densities and uses. The sizes of lots and required building setback distances for specific zones are described in city or county ordinances. Zoning can be used for almost any purpose. Historic preservation zones, redevelopment zones, and green belt zones are three. Before work is begun, compliance of the project with zoning requirements must be verified. Deviation from existing zoning can sometimes be allowed through political process. Obtaining such variances, however, usually requires a significant amount of time. “Planned developments” (not to be confused with development plans) can sometimes circumvent specific ordinance requirements if the developer can demonstrate that there is good cause and that the essence of the zoning is upheld. Mixed-use zoning, wherein commercial, business-professional, and residential uses are placed together, are sometimes allowed. Assessors’ parcel maps One of the first sources of information for engineers is assessors’ maps (Fig. 2.3). The original purpose of assessors’ maps is to locate and show property for the Figure 2.3 Assessor’s map (imperial units). Resources 25 purpose of tax assessment. These maps cover the entire land within the county. Originally, these maps were filed in books and given page or file numbers. In many cases, the use of terms book, page, and parcel are still used for finding maps even though books are no longer the major source for research. This information is now available on some city or county web sites. If not available on a web site or on a computer within the city or county offices, assessor’s maps are available in the assessor’s or tax collector’s office, usually located in the county offices. By knowing the cross streets near the site, the book where the map of the property is located can be determined from an index map. Within the assessor’s book is another index map to help locate the page (map) that actually shows the property. Reference is given at the edges of the page to show which book and page shows the adjacent properties. Each page is delineated to show property lines for several properties, and each property is given a lot number. Each property on the tax roles is identified with a number called the assessor’s parcel number and referred to as the APN. The number indicates book-page-parcel, such as 662-32-3 (Fig. 2.3). This property is shown in Book 662 at Page 32 as Parcel 3. The number is then listed in another “book,” where the address of the parcel, the name and address of the owner, the zoning, the assessed valuation of the property, and other information is given. In some counties where the information has not been computerized, this information and the assessors’ parcel maps have been converted to microfilm or microfiche, so that research is conducted at a microfiche projector rather than with books. When the maps are copied to computers or microfiche, their size changes. The change may result in an odd size that cannot be used with conventional measuring instruments. The result is that when the map is copied, the engineer may not be able to scale (measure) the drawing. Drawing scales on the maps facilitates the expansion or contraction of the map to a useful scale. Another factor that makes the use of assessors’ maps for large or linear projects difficult is that adjacent assessors’ maps may be of very different scales. In some cases, because of erratic timing and sizes of land developments, one assessor’s map may be inside another. The first step in determining ownership for a strip project is to change all the assessors’ maps in the affected area to the same scale and then to fit them together like a giant puzzle (Fig. 2.4). Other information may be shown on assessors’ maps. The names and file numbers (tract map numbers) of existing subdivisions and Record of Survey maps in the area may be given. The reference will be shown as a book and page in the Book of Maps filed at the recorder’s office. These maps will also probably be available on microfiche. Be alert to the fact that the records may not be current. Find out when the files were last updated, and be certain that you have the most current information. In some cases this information is available on a geographic information system (GIS described later), through the use of the Internet. Though not all jurisdictions have this information available, many do. Check it out first. If you are not able to find it using your best guess as to the address, call the office of the jurisdiction and get an Internet address from them. 26 Figure 2.4 Preliminary right-of-way map, composite of assessor’s parcel maps. Resources 27 Engineers can have the most current information at their fingertips, without leaving their offices. Distances along property lines may be shown on assessors’ parcel maps, but these are not legal dimensions and should be used only as approximations. True distances can be determined only from evaluation by a surveyor or civil engineer skilled in interpreting the legal descriptions found in deeds filed in the county recorder’s office or from title reports of the properties. Street names and widths may be shown, as well as some easements and rights-of-way. The information on the assessor’s map provides a useful sketch for following the legal description. It is of a scale and size that is easily carried and referred to. It also provides a map that can be given to the surveyors and other consultants working on the project in the early stages of development. With the reference numbers for subdivisions and Records of Surveys adjacent to the site, existing maps, and improvement or construction plans can be located. Remember, assessors’ parcel maps are graphic representations only. They do not show actual, legal property lines. Geographic information systems The information in a geographic information system (GIS) is composed of maps and plans of existing and proposed improvements that are selected to be integrated for some stated purpose. The information may consist of geographic or topographic information, including street maps, property and zoning information, existing and planned utilities locations, transportation systems, or any other information deemed useful. This information may be integrated into a single source in a computer system. This technology will provide a resource for a vast amount of information that can be made current within hours. Locating Land Before construction can begin, a clear and exact location of the property or right-of-way boundary must be established. The deed is the legal description of the property. Its interpretation should be made by a qualified professional (licensed) land surveyor (PLS) from a field survey. However, the deed alone is not sufficient for determining the legal property holdings. A title report is required. Title reports Title reports are documents prepared by title insurance companies, which ensure the legal ownership of property. Title reports provide the legal description as taken from deeds and list any claims to the property in the form of easements, mortgages, liens, taxes, and water and mineral rights. Title reports may also show stipulations and limitations on development. Title reports are important to engineers for determining the exact legal description of property. The description of the property can also be found on the deed filed in the county recorder’s 28 Chapter Two office, but that information is not sufficient. Subsequent to the original purchase, a portion of the property may have been sold or granted for an easement, or there may be taxes and other monetary interests held by others. If property is to be developed, its exact property lines and ownership must be known. The title report provides and guarantees the property information. If the land is developed according to where the owners think their property lines are and their neighbor disagrees, the property line dispute can end up in court. The developer must have a qualified surveyor determine the property lines through a field survey and exacting analysis. The earlier in the project the survey takes place, the less likely there will be a problem with property lines. Property descriptions In the simplest cases, a legal description of a property may be, for example, “Lot 1, Tract 5200, filed February 26, 1969, in Book 323 of Maps, at page 65, Santa Clara County Records.” In many cases, however, the legal description is more complicated and may continue for pages, describing the property by “metes and bounds” (explained later). If a subdivision map or monuments were used in the legal description of the property, the surveyor will have to establish their physical locations. Usually monuments are set at subdivision and lot or parcel corners or at changes in direction of right-of-way lines. Historically, monuments were significant topographic features described by the deed. At the turn of the twentieth century, surveyors would sometimes build their evening campfire at a property or section corner (given later). In the morning, the charcoal from the fire would be buried as the property corner. This was better than installing a wooden stake, because animals would not destroy the monument, and it would be preserved because charcoal does not deteriorate as quickly as wood. Another popular monument used was a mature tree or rock outcropping that could be easily located. Today, 3/4-in iron pipes (IPs), tagged with the surveyor’s license number, are commonly installed along subdivision boundaries. Cities often require that standard city monuments be installed at property corners and along centerlines of streets in new subdivisions. The following are some of the kinds of elements used in land descriptions. 1. Subdivision maps: Tract 5700, Map of W. E. Woodhams Tract, filed on March 4, 1965 in Book 376 of Maps, at page 31, Shasta County Records 2. Streets: The northwesterly line of Alum Rock Avenue 30.5 m (100 ft) wide 1 3. Other deeds: The deed from Henry W Smith, et ux, to George Davis, et ux, dated December 10, 1954, and recorded December 15, 1954, in Book 303 of Official Records, Page 288, Sonoma County Records. 4. Monuments: A 3/4-in IP at the southerly corner of Tract 5200 1 Et ux is a Latin abbreviation for “and wife,” et vir means “and husband,” and et al. means “and others.” Resources 29 Before a grid system was established to describe land, early settlers described their property by metes and bounds. Metes is measure. Bounds can be anything, such as a ridgeline or creek, that limits the parcel of land to be described. Early settlers described their property as extending from one landmark to another. In some cases the property was then measured by two men on horseback carrying a rope or leather thong between them. The rope was set at 100 varas—0.84 m (33 in). These original property boundaries are still valid, but the description has since been retraced using modern surveying instruments. The boundary is now described using bearings and distances and is called a metes-and-bounds description. When ownership of an irregular plot of land is transferred today, a Record of Survey or Boundary map may be prepared and referred to, but metes-and-bounds descriptions are not uncommon. Bearings are directions as measured east or west of due north or south. They must be exact, and so are measured in degrees, minutes, seconds, and decimals of a second and are determined in the following way. A circle is divided into 360 degrees (360°). Each degree is divided into 60 minutes (60'), and each minute into 60 seconds (60"). The course is described as a certain number of degrees, minutes, and seconds (from 0° to 90°) east or west of due north, or a certain number of degrees, minutes, and seconds east or west of due south. A line described as N 50°E can also be described as S 50°W. The direction of retracing the course determines whether the bearing is northeast or southwest (Fig. 2.5). In a metes-and-bounds description, the bearings and distances serve to traverse property. The following is an example of the metes-and-bounds description of the property in Fig. 2.6. (Distances are shown parenthetically in Imperial units in this description to facilitate understanding by the reader during the transition to metric units but should not be shown on maps and plans or included Metes and bounds. Figure 2.5 Determining bearings. 30 Chapter Two Figure 2.6 Figure for metes-and-bounds description. in descriptions. When writing descriptions using Imperial units, do not use abbreviations for “feet” or “acres”) All that certain real property situate in the City of Redding, County of Shasta, State of California, described as follows: Beginning at the point of intersection of the Northerly line of Main Street, 15.2 m (50 feet) wide, and the Easterly line of First Street, 12.2 m (40 feet wide); thence along said Easterly line of First Street N5°22'36"E, 61.4 m (201.50 feet) to the Southerly boundary of Tract 5700, filed March 4, 1965, in Book 376 of Maps, at page 31, Shasta County Records; thence along the said Southerly boundary of said Tract 5700, N89°52'22"E, 75.3 m (247.13 feet) to the Westerly line of Second Street, 18.3 m (60 feet) wide; thence along Second Street S5°22'36"W, 52.1 m (170.98 feet); thence along a curve to the right with a radius of 9.1 m (30.00 feet), through a central angle of 83°40'32" an arc length of 13.4 m (43.81 feet) to a point on the Northerly line of Main Street; thence S89°03'08"W, 67.3 m (220.66 feet) to the Point of Beginning. Containing 4532 km2 (1.12 acres) more or less. Accurate interpretation or writing of metes-and-bounds descriptions is an exacting skill that is beyond the scope of this book. For more information on this subject, see Land Survey Descriptions, by William C. Wattles. Townships and sections. The United States was surveyed by U.S. government surveyors and a grid system was established in the late 1700s and early 1800s as a result of political persuasion by Thomas Jefferson. The land was surveyed and marked into sections. As a general rule, monuments were set at section corners 1.609 km (1 mi) apart and quarter corners 0.805 m (1/2 m) apart. Even though the work was sometimes done under very difficult conditions and with instruments that were crude by today’s standards, the original monuments, when they can be found, hold the most credibility for determining the location of sections. The original surveys are recorded on “government plat maps,” and Resources 31 survey (call) notes are available from Bureau of Land Management (BLM) offices. Establishment of townships and sections is a complicated procedure, which is beyond the scope of this book. An idealization of the procedure is provided here. The establishment of townships is based on the latitudes and longitudes of the earth. Longitudes are imaginary lines running north and south through the poles. Each longitude is identified as from 0° to 180° east or west of Greenwich, England. Latitudes are lines extending around the earth, parallel to the equator, and divided into degrees, from 0° at the equator to 90° at the poles. Prominent geographical points are identified by latitude and longitude, and then referred to for further refinement. Mt. Diablo in Northern California is at latitude 37°51'30" North (the base line) and longitude 121°54'48" West (the meridian line). These are the reference lines for the references in descriptions using “Mt. Diablo Base and Meridian”—abbreviated MDM. There are two other base and meridian points in California—San Bernardino Base and Meridian, and Humbolt Base and Meridian. There are 37 base points throughout the United States. From these base and meridian lines, townships are established. Townships are rectangular blocks of land 9656 m (6 mi) square. They are described by their distance from the base and meridian. The land contained in the first 9656 m (6 mi) north of the base line is said to be in Township 1 North. The land within the first 9656 m (6 mi) south is said to be in Township 1 South. The land contained in the second 9656 m (6 mi) north is Township 2 North, and so on. The east and west limits of the township are measured in 9656 m (6 mi) increments east and west and are referred to as ranges. The township and range terms are abbreviated. T5N, R2E, MDM (Township 5 North, Range 2 East, Mt. Diablo Base and Meridian) is illustrated in Fig. 2.7. The township is further divided into sections of land approximately 1 mi square, containing approximately 259.01 ha (640 ac). The sections are numbered from 1 to 36, starting at the northeasterly corner of the township and continuing back and forth across the township in a zigzag manner (Fig. 2.8). The section is further divided into halves, quarters, quarter quarter sections, and so on. The quarters are established by bisecting the boundaries of the section. The points of bisection are called quarter corners. Lines are then drawn between quarter corners to establish quarter sections. The property described as “the North half of the Northeast quarter of the Southwest quarter of Section 26 T5N, R2E, MDM” is shown in Fig. 2.9. To interpret descriptions in this form, start reading at the end of the sentence and trace the process backward. Example 2.1 Determine the approximate distance between MDM and the west quarter corner of Section 7 T5N, R2E. Use Figs. 2.7, 2.8, and 2.9. T5N occupies the land between 38.62 and 48.28 km (24 and 30 mi) north of MDM. Section 7 lies between 0.64 and 0.80 km (4 and 5 mi) north of the south boundary of Township 5N. The west quarter corner is 0.08 km (0.5 mi) north of the section corner. Solution 38.62 km + 6.44 km + 0.80 km = 45.87 km north of the base (24 mi + 4 mi + 0.5 mi = 28.5 mi) 32 Chapter Two Figure 2.7 Township 5 North, Range 2 East, Mt. Diablo Base and Meridian. R2E lies between 9.66 and 19.31 km (6 and 12 mi) east of the meridian. Section 7 lies between 0 and 1.61 km (1 mi) east of the range line; the west quarter corner is on the west line (0 mi east of the range line) 9.66 km + 0 km + 0 km = 9.66 km east of the meridian (6 mi + 0 mi + 0 mi = 6 mi) The west quarter corner of Section 7 is 45.87 km (28.5 mi) north and 9.66 km (6 mi) east of MDM. The exact dimensions of the distances along the sides of a section and portions of a section will vary from expected dimensions because of inaccuracies in the original surveys. Also, longitudes (meridian lines) converge from the equator to the poles. When Resources Figure 2.8 33 Township divided into sections. adjustment is made for the convergence, the sections along the north and west of the township were made to accommodate the variance. Coordinate systems One of the most useful tools at the engineer’s disposal is coordinate systems. Use of coordinate systems is great and still increasing with the development of modern surveying equipment and CADD systems. A basic understanding of their use is imperative, even though step-by-step procedures can be followed with Figure 2.9 Section 26, T5N, R2E, MDM. 34 Chapter Two computers to determine information without understanding the basics. Without a basic understanding, coordinates are meaningless numbers. Coordinates are numbers that represent distances north and east of a reference point. The reference point can be real, such as Mt. Diablo Base and Meridian or it can be fictional. Coordinate systems employ trigonometric relationships between points to determine distances and bearings exactly. The use of a coordinate system also facilitates location and plotting of property corners and other survey points with accuracy and precision. The reference point is at the point of the 90° intersection of a north-south axis with an east-west axis. The north-south axis can be true north, magnetic north, or an assumed north. The point can be given coordinates based on another coordinate system to which ties are made, or it can be given assumed coordinates that are convenient to the task. In Fig. 2.10, point A is the reference point and has been assigned assumed coordinates of 1000.000N and 2000.000E. When traversing a course that is 152.4 m (500.00 ft) long on a bearing of N 50°E from point A, the course will end at point B. The difference in northerly coordinates is called the latitude. The difference in easterly coordinates is called the departure. A right triangle is formed by the course, N 50°E, 152.40 m (500.00 ft), the latitude measured along the north-south axis, and the departure as measured from point C to point B. From trigonometry we know that the cosine of angle CAB (50°) is equal to the length of AC divided by the length of course AB . cos50° = AC AB This formula can be manipulated to yield the unknown latitude (AC). AC = AB × cos 50° = 152.40 m × 0.642788 = 97.96 m AC = AB × cos 50° = 500 ft × 0.642788 = 321.39 ft A point established using coordinates. Figure 2.10 Resources 35 The northing coordinate for point B is 1000.000N + 97.96 m = 1097.96N (1000.000N + 321.394 ft = 1321.394N) Trigonometry also gives us the relationship that the sine of angle CAB (50°) is equal to the length of CB divided by the length of course AB. sin50° = CB AB Again manipulating the formula, the departure CB can be determined. CB = AB × sin 50° = 152.40 m × 0.766044 = 116.75 m CB = AB × sin 50° = 500 ft × 0.766044 = 383.02 ft The easterly coordinate for point B is 2000.000E + 116.75 m = 2116.75E (2000.000E + 383.022 ft = 2383.022E) If the coordinates of points A and B are known but the distances and bearing between them are not, the course between them can be determined. This procedure is called inversing. The northerly coordinate of point B (1097.96) minus the northerly coordinate of point A (1000.00) gives the latitude 97.96 m (321.39 ft). The easterly coordinate for point B 2116.75 (2383.02) minus the easterly coordinate of point A (2000.00) gives the departure 116.75 m (383.02 ft). From trigonometry we know that the tangent of the angle CAB is tan ∠ CAB = = tan ∠ CAB = = CB CA 116.75 m = 1.1918 97.96 m CB CA 383.02 ft = 1.198 321.39 ft 36 Chapter Two The angle, the tangent of which is 1.19313 is 50°. To find the length of the line, we again use trigonometry: sin ∠ CAB = AB = = sin ∠ CAB = AB = = CB AB CB sin ∠ CAB 116.75 m = 152.4 m sin 50° CB AB CB sin ∠ CAB 383.02 ft = 500 ft sin 50° A series of courses is called a traverse. The traverse can be continued around a piece of land and back to the point of beginning to delineate property lines such as those shown in Fig. 2.6. An illustration of how to determine coordinates for the property in Fig. 2.6 is given in Fig. 2.11. The traverse starts at assumed coordinates at the northeast corner of the property. Figure 2.11 Calculation of coordinates for boundary of property in Fig. 2.6. Resources 37 The assumed coordinates chosen for that point are large enough that the property will have all positive (not negative) coordinates and small enough that unnecessary numbers will not have to be carried. The number for the easting coordinate was chosen with the same considerations and so that the easting coordinates would not be confused with the northing coordinates. When a traverse contains one or two “unknowns” but the beginning and ending coordinates are known, the unknown information can be calculated. The unknowns can be: The bearing and distance of one course The bearings of two courses The distances of two courses The bearing of one course and the distance of another course Procedures for solving unknowns in two courses using trigonometry are long and complicated, and there are many opportunities for errors. Fortunately, computers and hand-held calculators do this task easily and quickly when simple, step-by-step instructions are followed. You may find that occasionally you will have a problem that the computer cannot solve because of the location of the unknown information in relation to the known information. When this happens, consider that you may be able to solve for unknowns using the geometry and trigonometric formulas learned in high school. It is seductive thinking that the computer can always solve problems most easily. That is not always the case. You may also be able to solve for the unknowns by using some creative thinking about relocating or realigning what is known. One technique that can be helpful is to rotate the traverse, so that one course lies due north. Then solving for courses gives you the angles between courses. Knowing angles between the courses, may give you enough other information to solve for unknowns using the computer. Existing and proposed maps and plans There are existing maps and plans useful for developing proposed project sites. A description of the kinds of maps and plans that can be used as resources, is described at length in Chap. 4. In the private sector, it is not unusual for work on a desirable piece of land to have been begun by one developer and then been suspended because of a change in the economy or because of a lack of sufficient planning by the developer. Even though the new owner may have a different concept, there will be valuable information contained on the earlier maps and plans. A thorough search must be made to collect all available resources. When these resources are located, you may find that much of the information you need is already available. After comparing a recent topographic map with observed conditions on a site visit, you may decide that it can be used to begin design as long as you perform a field survey to check critical points. Public works officials are well aware of the effect of time and inflation on the cost of land, so it is not unusual for them to have set aside land through zoning or purchases for transportation systems or other 38 Chapter Two public purposes. New public works projects can be in the planning stages for years before construction actually begins. If a planned public works project may affect your project, you must do a thorough investigation of its impact. Surveys Engineering for land development depends on professional land surveying. Even though there may appear to be sufficient information as to the topography and property lines from existing maps and plans, the engineer must verify the conditions with a field survey and analysis of the field information. Surface and subsurface topography and property-line monuments are changed through both conscious effort and accidents. Engineers take responsibility for the maps and plans they sign. They must be certain that the information is correct. Control surveys Control surveys establish and tie together, with the use of trigonometry, various points on the ground that provide reference points for further surveying. They require a high degree of precision and are used throughout the design and construction of a project. Boundary surveys Determination of property boundaries requires sophisticated procedures and specialized expertise. Because of the importance of land ownership both monetarily and emotionally, this is one task that only experienced, licensed land surveyors should perform. It is not unusual to find a number of similar monuments at the approximate corner of a property. The surveyor must analyze the total property boundary and other factors before determining by a “preponderance of evidence” which monument, if any, is correct. When boundary surveys are not performed correctly, overlaps in and gaps between properties may be created, and the chances of a civil suit increase. Photogrammetry Photogrammetry is a surveying process that utilizes aerial photographs. By locating survey control points on the ground using conventional surveying methods and marking them large enough so that they will be clear on aerial photographs, aerial maps can be produced that can be measured precisely. These photographs can be prepared to whatever scale is most useful to the engineer and to the degree of precision needed. Using complicated procedures and equipment, the photographs can be viewed in three dimensions. Skilled photogrammetrists can then produce maps with contour lines and other topography. Figure 2.12 Record of Survey map (imperial units). 39 40 Chapter Two Topography Each project requires specific topographic information. Topography produced from aerial surveys may not provide information that is specific enough. Aerial surveys also do not provide subsurface information, such as flow-line elevations on storm and sanitary sewers. Underground elevations of water and gas lines can be estimated by locating the elevations of their valves, but more specific information may be necessary. When this is the case, the pipeline must be “potholed,” so that the top of the pipe is exposed for the surveyors to measure. It is particularly important for the engineer to investigate the site. What may show up on an aerial map simply as a building does not explain the importance or cost of the building. Whether the building is a rundown shack or houses multimillion-dollar equipment cannot be determined from an aerial survey alone. On the surface, areas where the improvements connect to existing conditions is particularly important. When connecting to an existing roadway, minimum information that must be gathered are elevations at the centerline, at the gutter line or flow line, and at the top of curb for a distance of 15 to 30 m (50 to 100 ft) in order to design smooth connections. Further, the next upstream and downstream catch basins or other drainage facilities must be surveyed in order to determine the areas of drainage basins. Global positioning systems (GPS) By 1993, twenty-four satellites were in place at an altitude of 17700 km (11,000 mi) to broadcast three-dimensional positioning data 24 hours a day to anywhere in the world. This is called global positioning systems (GPS). The technology has been used since 1979 for navigation and became available to civilians in 1983. It was used in 1984 as survey support for construction of the Stanford Linear Accelerator Extension and was planned for use to support construction of the Superconducting Supercollider in Texas. Measurements can be made to within 1 mm. GPS surveying transcends many disciplines and requires understanding of orbital mechanics, time, relativity, gravity, mathematics, physics, earth dynamics, and statistics, as well as the limitations caused by the effects of the troposphere and the ionosphere on GPS signals. However, the instruments themselves have been made easy to use and, with proper supervision, surveyors can be operating the antenna and data collectors in a short time. The use of GPS is clearly indicated for providing control surveys for any large project. Surveying a series of lines to a benchmark while hiking over hills and down canyons, around buildings or other obstacles to the line of sight, or around a bay, can be very time consuming and expensive. With the GPS, the survey can be performed any time, day or night, in any weather, and without line of sight and with much less opportunity for error. As the technology improves and the cost of instruments drops, use of the GPS will increase. There are now instruments available that enable a single surveyor to set up a microstrip antenna attached to a previously established GPS point Resources 41 and walk about a site collecting data with a hand-held data collector. The data can later be downloaded for printing of surface and subsurface topography and analyzed for preparation of control and boundary maps. Working with Computers The computer revolution of the 1980s has affected the civil engineering profession enormously. The use of computers and state-of-the-art software to perform complex operations and manipulate huge amounts of information has become necessary for designers to remain competitive. Use of CADD is now commonplace in civil engineering design and land development. Many public agencies currently require the work product of plans and specifications to be submitted on electronic medium using specified software. Software that allows translation from one computer language to another is improving quickly. In most cases, developing the design for a project on one software product, and then presenting it in a format that can be used by another software product can be accomplished. When sharing electronic files, it is important to name the platform (DOS, Windows or some other maker), and the edition or release number of the software used to create the file. Otherwise, there could be problems for the recipient in opening and using the file. A brief description of available computer resources is presented in this section. More specific information on particular software is provided where we discuss the area in which it will be used. Keep in mind that the computer industry is evolving so rapidly that in a very short time additional and better software may be available. If software is of particular interest to you, first check the references section of the chapter covering the subject of interest. If you do not find what you need there, refer to current magazines such as Civil Engineering, Engineering News Record, or Civil Engineering News. A word of caution is appropriate here. There is hardly a person who uses computers who has not encountered a computer virus at one time or another. When electronic information is being shared, even from very reliable sources, it must be checked for viruses before being installed. Even after taking that precaution, most engineers backup or copy computer files to floppy disks, tapes, or compact disks frequently. A virus or other breakdown of the system can incur huge costs to recreate information. What can be even more important is the time lost. Developers are not sympathetic to excuses that you cannot meet their schedule because of “computer problems”. The computer information can be backed up to tape through manual or automatic programs. Two copies should be made and one copy stored at a different location such as in a safety deposit box. Computer-aided design and drafting The use of CADD software is now being required by many public agencies. Plans prepared on electronic ...

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