Use of Geophysics for Transportation Projects (2006)

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13 This chapter details the approach used for this synthesis in gathering specific information regarding the use of geophysics among state DOTs and selected federal and Canadian trans- portation agencies. General data regarding the demographics of who is involved with geophysical investigations, the way geophysics is implemented within these agencies, knowledge of available resources, and the amount of work performed an- nually will be discussed. Data collection for this synthesis was undertaken in the following sequential process: 1. A 63-question electronic survey was developed using primarily a multiple-choice selection and was produced as an electronic questionnaire for e-mail distribution. 2. Fifty-one U.S. state DOTs (including the District of Columbia), 8 federal agencies, and 11 Canadian provinces (a total of 70 agencies) were requested to complete the questionnaire. 3. As responses were received, particular DOT or Cana- dian respondents were contacted for additional ques- tions or a brief interview. Interviews were focused on either clarifying any discrepancies found in the ques- tionnaire or to discuss the opportunity to obtain addi- tional information (e.g., case histories). 4. Agencies that did not reply within several months were recontacted individually. During this process it was determined that the initial state representatives were no longer at their jobs (i.e., promotions, retirement, left the agency, etc.), e-mail addresses were incorrect as a result of changed names or extensions, or the ques- tionnaire was sent to a person who was too busy or not interested in responding. In every case, another person was selected to complete the survey. 5. Data were entered into Microsoft Excel for informa- tion management and development of graphical illus- tration of the results. 6. Quality controls of the questions, responses, and charts and tables were established. 7. All the results from steps 5 and 6 are presented in Appendix C, but selected charts are presented in the text. Additionally, a few questions requested written comments, and these comments are included in tables in Appendix C. Appendix B includes the entire electronic questionnaire as distributed. Appendix C provides graphical and tabular summaries of all the survey responses. A total of 63 agency responses, 90% of the questionnaires sent to agency repre- sentatives, were returned. The completed questionnaire received from the Port Authority of New York & New Jersey was not solicited, and Colorado, Michigan, Oregon, and Alberta each replied with at least two completed surveys. Almost 40% of the responses received were obtained by means of a personal communica- tion requesting that someone within the agency other than the initial recipient of the questionnaire complete the survey. Replies were received from all 50 state DOTs, plus the Port Authority of New York & New Jersey and the District of Columbia (52 U.S. agencies). Seven of 11 Canadian provin- cial agencies plus the municipality of Edmonton also replied. In addition, three U.S. federal agency responses are repre- sented in this synthesis. No effort was made to solicit re- sponses from municipal, county, or other nonstate agencies (i.e., Edmonton’s response was not solicited). It was necessary to first identify who among the 63 re- spondent agencies is not currently using geophysics. Figure 1 (chapter one) identifies the total number of responses and de- notes the agency distribution of nonusers. Approximately 12% of state DOTs, 25% of Canadian transportation agencies, and 33% of federal agencies indicated that they do not use geophysics in their programs. To maintain a relatively uni- form analysis process, the agencies that do not use geophysics were not included in the remaining analysis. Figure 2 shows the distribution of agency response by the percentage of the remaining 58 respondents that do implement geophysics on their transportation projects. Ninety-five percent of the re- spondents discussed throughout this synthesis are either U.S. state or Canadian provincial DOTs. During creation of the database it quickly became apparent very that (1) not all respondents answered all of the questions; (2) some respondents completed questions with multiple an- swers, when only one answer was requested; and (3) in a few cases both “Yes” and “No” answers were applied to the same question. Discretion was used and the interviews helped, but not in all cases. Therefore, for each chart presented there is an N value in the corner of the graph or in the caption that indi- cates the actual number of reliable answers used to assess the overall response to that particular question. For most of the questions the results are based on 58 respondents (i.e., com- pleted questionnaires from agencies that use geophysics), but CHAPTER THREE INFORMATION SOURCES AND GENERAL RESPONSES

14 the N value is necessary to understand the result. This is particularly true for questions that recommended multiple re- sponses (e.g., Questions 17, 22, and 24). Figure 3 shows that 68% of respondents apply geophysi- cal technologies on an “occasional” basis for their projects. This indicates that the number of transportation agencies us- ing geophysics is high, but its frequency of use is quite low. Results from Part 1 of the survey are presented in graphical format in Appendix C, Part 1—General. Part 1 of the questionnaire is summarized here: • Forty-five percent of the agencies have used geophysics only in the past 10 years, 26% in the past 5 years, and just under 10% in just the past year (Question 1). • Those primarily using geophysics are the geotechnical engineers and geologists (64%) (Question 2). • Only 4% (three agencies) provide any training related to geophysics (Question 4). • Fourteen agencies conduct between 75% and 100% of the geophysics with in-house capabilities, 24 agencies do 75% to 100% of their investigations using Request for Proposal (RFP) contract procedures, and 7 agencies con- duct 75% to 100% of their geophysical investigations us- ing Indefinite Quantity (IQ) contracts (Question 3). Regarding the recently published (2003) FHWA Geo- physics Manual (10) designed specifically to aid state, federal, and other highway engineers use and learn more about how to apply geophysics on their projects: • 69% are aware of the manual, • 46% own the manual, • 14% have used the hardcopy version, • 16% have the CD-ROM version, • 5% use the CD-ROM, • 50% know of the website, and • 24% use the website for project work. This demonstrates the need to better spread the word and educate transportation agencies about the manual and the value of this publication (in all of its formats). As more en- gineers are exposed to the website, more will understand its purpose and put it to use. Because 53% of the agencies con- duct between one and five geophysical investigations per year (Figure 4), there is reason to believe that the FHWA manual may help increase this number. As Figure 5 shows, nearly 60% of respondents indicated that the use of geophysics has been increasing in their agencies over 3 95 0 2 0 0 N=58 0 10 20 30 40 50 60 70 80 90 100 Pe rc en t Federal Agency State/Provincial Agency County Agency Municipal Agency Private Organization Toll and Turnpike Authority No Response FIGURE 2 Type of transportation agency or organization that implements geophysics on transportation projects. 3 3 68 3 23 0 10 20 30 40 50 60 70 80 90 100 Pe rc en t Primary Major Minor Occasional No Response N=59 FIGURE 3 Involvement with geophysical investigations. 9 56 12 5 5 10 3 0 10 20 30 40 50 60 70 80 90 100 Pe rc en t <1 1 to 5 6 to 10 11 to 15 16 to 20 21 or > No Response N=58 13 8 5 8 59 38 3 0 10 20 30 40 50 60 70 80 90 100 Pe rc en t Yes No No Response <25% 25 to 50% 50 to 75% >75% N=58 R es po nd en ts N=34 FIGURE 4 Typical number of geophysical investigations conducted by agencies each year. FIGURE 5 Percentage of increase in level of effort for geophysical projects over the past 5 years.

15 the past 5 years, and 13 agencies (of those answering “Yes”) showed an increase in use of greater than 50%. The FHWA manual and other educational efforts could continue this trend, because 66% of the respondents and 54% of the agency’s ex- periences are favorable toward the use of geophysics (i.e., “good” to “excellent” responses for Questions 14 and 15). Questions 16 and 17 are two of the most important ques- tions for this survey. If the agencies that do not use geo- physics can understand the “greatest value” of implement- ing geophysical techniques currently used by their fellow DOTs, as shown in Figure 6 (Question 16), more are likely to implement the technology. The data in Figure 6 support the technical panel’s supposition that it is cost, acquisition speed, and better subsurface coverage that are the primary benefits to a field program when geophysics is included. Figure 7 shows that some (14) believe it is the expense as- pect of a program that may restrict its use, but the results in- dicated that a large portion admit that the low usage is the result of a lack of understanding and/or confidence in the technology. This synthesis is focused on the use of geophysics for geo- technical projects. However, because NDT technologies overlap with the methods and technologies discussed herein, it was crucial to distinguish the two and determine that the respondents knew the difference, as defined by the question- naire and discussed in chapter one. With 91% reporting that they understood the difference (see Question 18), the re- mainder of the synthesis can reliably discuss issues regard- ing the application of geophysical technologies. It will be shown, however, in later chapters that there is overlap and that there is still confusion whether a field investigation is geophysics or NDT. The distinction and understanding of the difference will only come with training, time, and experi- ence. NDT is being used quite frequently by respondents of this survey, as indicated by Figure 8. The broad range of ap- plications used during the past 5 years indicates its value to the engineering community. 21% 19% 17% 15% 10% 10% 7% 1% Data Acquisition Speed Cost Benefit Better Subsurface Characterization 2D, 3D Subsurface Assessments Other Results Presentation No Response N=162 Other 14 13 4 23 28 7 33 27 9 1 0 10 20 30 40 50 60 R es po nd en ts Cost Acquisition Issues Timeliness of Results More Questions Non-Uniqueness Results Format Lack of Understanding Lack of Confidence Other No Response N=159 28 15 4 20 21 24 11 13 0 10 20 30 40 50 60 R es po nd en ts Pavement Condition Bridge Superstructure Baseline Measurements Concrete Condition Bridge Substructure Construction QA/QC Other No Response N=136 FIGURE 6 Greatest value geophysics lends to agency transportation projects. FIGURE 7 Greatest deterrent to using geophysics on transportation projects. FIGURE 8 Types and percentages of applications used for NDT in the past 5 years.