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SUBSURFACE UTLITY ENGINEERING FOR HIGHWAY PROJECTS: A STUDY OF UTILITY IMPACT RATING AND BENEFIT-COST ANALYSIS
SUBSURFACE UTLITY ENGINEERING FOR HIGHWAY PROJECTS: A STUDY OF UTILITY IMPACT RATING AND BENEFIT-COST ANALYSISABSTRACT Accurate locations of buried utility infrastructures are very important for utility owners, utility managers and engineers, designers, and contractors that perform new installations, repairs, and maintenances in highway projects. A lack of reliable information on underground utilities not only can result in property damages, construction delays, design changes, claims, injuries, and even deaths, but also cause traffic delays, local business disruptions, environmental problems, and utility service breakdowns. Subsurface Utility Engineering (SUE) is an engineering process to reduce the potential of underground utility conflicts in the project planning phase. SUE utilizes new and existing technologies to accurately identify, characterize, and map underground utilities with three major activities including designating utilities, locating utilities, and data management. SUE can be the most suitable method for mitigating risks associated with uncertain underground information. Although many damage prevention practices have existed, the damage prevention practice using the SUE concept has not been developed for contractors, designers, engineers, and other stakeholders associated with or impacted by underground utilities. This study focuses on an in-depth analysis of SUE projects executed by Penn DOT districts. Based on this analysis and the utility impact score which refers to utility complexity at the construction site, a decision-support tool called utility impact rating form has been developed to determine which projects should include SUE and identify the appropriate levels of SUE investigation to be used. The computerized utility impact rating form is developed using Visual Basic software to provide a graphical interface for the purpose of enhancing the efficiency of the calculation and selection processes. A detailed benefit-cost analysis is also performed on twenty-two SUE projects and eight non-SUE projects. All of the projects show a strong relationship between SUE benefit-cost ratio and complexity level of buried utilities. The analysis clearly indicates that there is no relationship between SUE benefit-cost ratio and project cost and also no relationship between complexity level of buried utilities and project cost. The conclusion of this study is that SUE quality levels A and B should be based on the complexity of the buried utilities at the construction site to minimize associated risks and obtain maximum benefits. TABLE OF CONTENTS Page LIST OF FIGURES ix LIST OF TABLES x ACKNOWLEDGEMENTS xi CHAPTER 1 INTRODUCTION 1 1-1 Background 1 1-2 Objective, Scope, and Composition of the Study 4 CHAPTER 2 SUBSURFACE UTILITY ENGINEERING 6 2-1 Traditional Practices for Locating Underground Utilities 6 2-2 Subsurface Utility Engineering 9 2-2-1 SUE Practices in Department of Transportations 10 2-2-2 SUE Practices in Private Sectors 12 2-2-3 Quality Levels of SUE 14 2-3 American Society of Civil Engineers 17 2-4 American Association of State and Highway Transportation Officials 18 2-5 Federal Highway Administration 19 2-6 General Accounting Office 20 CHAPTER 3 GEOPHYSICAL TECHNIQUES AND VACUUM EXCAVATION 22 SYSTEM 3-1 Geophysical Techniques 22 3-2 Applicable Geophysical Techniques 23 3-2-1 Pipe and Cable Locator 24 3-2-2 Ground Penetrating Radar 25 3-2-3 Terrain Conductivity Survey 26 3-2-4 Resistivity Survey 27 3-2-5 Metal Detector 28 3-2-6 Magnetic Survey 30 3-2-7 Acoustic Survey 31 3-2-8 Thermal Survey (Infrared Method) 33 3-2-9 Gravity Survey 34
| 3-2-10 Seismic Survey | 35 |
| 3-3 Factors Affecting Accuracy of SUE | 36 |
| 3-3-1 Type of Utility | 36 |
| 3-3-2 Material of Utility | 37 |
| 3-3-3 Depth of Utility | 37 |
| 3-3-4 Type of Soil | 38 |
| 3-3-5 Ground Surface Condition | 38 |
| 3-3-6 Access Point of Utility | 39 |
| 3-3-7 Internal Condition of Utility | 39 |
| 3-3-8 Density of Utility | 40 |
| 3-3-9 Special Materials for Detecting Non-Metallic Utilities | 40 |
| 3-3-10 Qualified SUE Consultants | 41 |
| 3-3-11 Other Factors | 41 |
| 3-4 Vacuum Excavation Systems | 41 |
| CHAPTER 4 PAST EXPERIENCE IN APPLICATIONS OF SUE | 43 |
| 4-1 General SUE | 43 |
| 4-2 Benefit-Cost Analysis of SUE | 46 |
| 4-3 Geophysical Techniques of SUE | 52 |
| 4-4 Limitation of Existing Studies | 56 |
| CHAPTER 5 UTILITY IMPACT RATING | 57 |
| 5-1 STEP 1 | 59 |
| 5-2 STEP 2 | 60 |
| 5-3 STEP 3 | 61 |
| 5-4 Complexity Factors | 65 |
| 5-4-1 Density of Utilities | 65 |
| 5-4-2 Type of Utilities | 66 |
| 5-4-3 Pattern of Utilities | 66 |
| 5-4-4 Material of Utilities | 67 |
| 5-4-5 Access to Utilities | 68 |
| 5-4-6 Age of Utilities | 68 |
| 5-4-7 Estimated Total Utility Relocation Costs | 69 |
| 5-4-8 Estimated Project Traffic Volume | 69 |
| 5-4-9 Project Time Sensitivity | 70 |
| 5-4-10 Project Area Description | 70 |
| 5-4-11 Type of Project/Section/Location | 71 | ||
| 5-4-12 Quality of Utility Record | 72 | ||
| 5-4-13 Excavation Depth within Highway Right-of-Way | 72 | ||
| 5-4-14 Estimated Business Impact | 73 | ||
| 5-4-15 Estimated Environmental Impact | 73 | ||
| 5-4-16 Estimated Safety Impact | 74 | ||
| 5-4-17 Other Impact Factors | 74 | ||
| CHAPTER 6 COMPUTERIZED UTLITY IMPACT RATING FORM | 75 | ||
| 6-1 Computerized Utility Impact Rating Form | 76 | ||
| 6-2 System Validation | 81 | ||
| 6-2-1 Project Stopped at STEP 1 | 81 | ||
| 6-2-2 Project Stopped at STEP 2 | 83 | ||
| 6-2-3 Project Stopped at STEP 3 | 84 | ||
| CHAPTER 7 SUE BENEFIT-COST ANALYSIS | 88 | ||
| 7-1 Benefit-Cost Analysis | 89 | ||
| 7-1-1 Benefit-Cost Analysis of SUE projects | 89 | ||
| 7-1-2 Benefit-Cost Analysis of Non-SUE Projects | 90 | ||
| 7-1-3 Benefit Factors of SUE | 91 | ||
| 7-1-3-1 Utility Relocation Cost | 91 | ||
| 7-1-3-2 Utility Damage Cost | 92 | ||
| 7-1-3-3 Emergency Restoration Cost | 93 | ||
| 7-1-3-4 Traffic Delay Cost | 93 | ||
| 7-1-3-5 Business Impact Cost | 94 | ||
| 7-1-3-6 User Service Cost | 94 | ||
| 7-1-3-7 Environmental Impact Cost | 95 | ||
| 7-1-3-8 Information Gathering and Verification Cost | 96 | ||
| 7-1-3-9 Legal and Litigation Cost | 96 | ||
| 7-1-3-10 Overall Efficient Utility Design and Construction | 96 | ||
| 7-1-3-11 Other Utility Related Costs & Benefits | 97 | ||
| 7-1-4 Cost Factors of SUE | 98 | ||
| CHAPTER 8 RESEARCH RESULTS | 99 | ||
| 8-1 Benefit-Cost Analysis | 99 | ||
| 8-2 Complexity Level | 106 | ||
| 8-3 Benefit-Cost Analysis and Complexity Level | 109 | ||
| CHAPTER 9 SUMMARY, CONCLUSIONS, AND RECOMMENDATIONS | 113 | ||
| 9-1 SUMMARY | 113 | ||
| 9-2 CONCLUSIONS | 115 | ||
| 9-3 RECOMMENDATIONS | 116 | ||
| REFERENCES | 117 | ||
| APPENDIX A: Case Studies from Penn DOT Districts | 123 | ||
| APPENDIX B: Utility Impact Rating Form | 154 | ||
CHAPTER 1 INTRODUCTION The first chapter presents the background and objectives of this study. Overall organization of the study is provided in the end of this chapter. 1-1. BACKGROUND Nearly 20 million miles of underground pipelines, cables, and wires in the United States have been built since World War II and designed for lifetimes of 20-50 years (Sterling 2000). Increased population and industrial expansion have increased demands on the underground utilities, and numerous underground projects have been developed to meet the demands. In this study, underground projects mean construction projects including any excavations. However, the expansion of underground projects has resulted in underground utility conflicts that might cause increased construction costs, construction delays, utility damages, change orders, claims, fatal injuries or even deaths of workers, outages of facility service, and other social and environmental problems. In particular, damage to underground utilities has been identified as one of the most dangerous problems for the construction industry. Doctor et al. (1995) reported that the number of U.S. utility damages in 1993 was more than 104,000 hits, and third-party damages by gas pipeline hits exceeded $83 million of the total damage cost. Nelson and Daly (1998) stated that cable damages in U.S. The western exceeded 2,000 hits in one month and averaged over 1,000 hits per month. In March 1999, a telephone utility hit cut-off service for 12,000 customers in Colorado. In general, statistics of reported damages may be underreported, because social costs such as traffic delay cost and business impact cost and environmental costs due to utility damage are not properly quantified. Heinrich (1996) stated that an accident cost reported as $15,000 was actually closer to $313,000, almost 20 times higher than the reported cost. The American Institute of Constructors (AIC) also identified damage to underground utilities as the third most important crisis for contractors (Reid 1999). Therefore, damage prevention to underground utilities must be one of the most critical issues for owners, designers, and contractors to pursue successful underground projects. The design of underground utility projects has traditionally relied on existing records or one-call systems. However, existing information on underground utilities is commonly incorrect, incomplete, and inadequate in as-built drawings and composite drawings, which incorporate all of the utility records for different owners. Existing records and visible feature surveys by site visit are typically 15-30% off the mark and sometimes considerably worse (Stevens and Anspach 1993). Thus, the one-call system was developed to overcome the limitations of using existing records and site visits. The one-call system is a state-regulated program that requires utility owners to mark the locations of their utilities on the ground surface around any proposed excavation area. However, the information provided by the one-call system commonly is not enough to accurately locate underground utilities. Sterling (2000) reported that 56% of the gas pipeline damages in 1995 happened under the one-call system and 25% of hits on existing utilities were due to mis- locations. He also stated that there are several inadequacies of current one-call systems in use by the industry. As a more systemic damage prevention concept for underground utilities, subsurface utility engineering (SUE) was introduced about two decades ago. SUE is an engineering process that utilizes new and existing technologies to accurately identify, characterize, and map underground utilities early in the development of a project. The use of SUE allows not only more effective damage prevention but also more successful completion of underground projects, including roadway/highway projects, underground pipeline projects, and other projects which require any excavations. The successful use of SUE should be initiated with the appropriate selection of SUE quality levels. However, different quality levels and different application conditions pose challenges in selecting the appropriate quality levels. 1-2. OBJECTIVE, SCOPE, AND COMPOSITION OF THE STUDY A key objective of this study is to develop a decision-support tool for appropriate selection of SUE quality level and a benefit-cost analysis of SUE for highway projects. Based on in-depth analysis of data projects and utility impact scores which refers to utility complexity at the construction site, a decision-support tool, called utility impact rating form, is developed to determine which projects should include SUE and identify the appropriate levels of SUE investigation to be used. The computerized utility impact rating form is developed using Visual Basic software to provide a graphical interface for the purpose of enhancing the efficiency of the calculation and selection processes. A detailed benefit-cost analysis is also performed on twenty- two SUE projects and eight non-SUE projects. In this study, SUE projects mean construction projects which utilize SUE and non-SUE projects mean construction projects which do not utilize SUE. The proposed decision-support tool and the benefit-cost analysis can help owners and designers to effectively select SUE quality levels and enable safer construction conditions. All project data for this study are provided by Penn DOT. If project data from other states are used for this study, the results can be different because each state has different law/regulations to carry out projects. Thus, the application of the results of this study may be limited to projects conducted in Pennsylvania. This study is presented in nine chapters. The first chapter presents the introduction, including the background and the objective of this study. In the second and third chapters, comprehensive information about SUE is presented, including quality levels and geophysical techniques. The fourth chapter provides existing literature reviews about SUE. The fifth chapter explains utility impact rating. The sixth chapter shows and verifies the computerized utility impact rating form, using Visual Basic Software. The seventh chapter explains benefit-cost analysis of SUE and the eighth chapter presents research results; the last chapter summarizes the results of this study and provides recommendations for future studies. SUBSURFACE UTLITY ENGINEERING FOR HIGHWAY PROJECTS: A STUDY OF UTILITY IMPACT RATING AND BENEFIT-COST ANALYSIS
