Freight Transportation Surveys (2011)

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62 CHAPTER FIVE SUMMARY AND CONCLUSIONS (A thirteenth category accounted for “other” surveys, reported by respondents to the survey of practitioners but not otherwise categorized.) A web-based survey of practitioners was the primary source of information for the synthesis. The survey was sent to all state departments of transportation (DOTs), as well as to selected metropolitan planning organizations (MPOs) that were known to be active in recent freight planning activ- ities. These were the primary intended audiences. To further broaden the coverage, the survey also was sent to selected marine and airport authorities, academics, and commercial freight data purveyors. In total, 74 individual agencies were contacted. This generated 56 responses, including 45 state DOTs and eight MPOs. The survey of practitioners solicited information on several topics, including survey costs, prac- titioners’ requirements for data, the data that are available to them and how these are used, and practitioners’ use of ITS technologies for surveys and data collection. Practitioners also were asked to assess how well the available data met their needs. The results provided a wide range of responses to virtu- ally all the questions. However, some tendencies emerged from the state of the practice: The range of applications was broad, with the most • common applications being policy and infrastructure capacity planning. Modeling was well down on the list: although data needs for modeling and forecasting were cited as an important reason for this synthesis, the find- ings indicate an interest in the use of freight surveys for many applications. The large number of “other” applications also suggests that new issues and needs are emerging and must be addressed. Trucks were the dominant mode of interest, but data • for other modes also were of interest. There were some common elements in the type of data required for each mode: trip origin, destination, the characteristics of the load carried, and vehicle/vessel (equipment) profiles. Additional and more specific information was required for trucks, notably including speed and emission data. Among the 12 types of surveys, roadside/intercept sur-• veys (i.e., the most traditional form of truck survey) were cited most frequently; however, each of the other types of surveys was used as well. SUMMARY OF FINDINGS This synthesis has reviewed the state of the practice in freight transportation surveys, with a focus on truck freight in both urban and inter-urban settings. A survey of practitioners and a review of case studies found that freight transporta- tion surveys, like the subject of freight transportation itself, are complex and multifaceted. A single, all-encompassing survey or data set does not exist; and perhaps as important, there is no commonly accepted taxonomy of survey types and definitions. Different types of surveys can be used to develop data for a given need (e.g., several types of surveys are used to gather trip origin-destination information). Nei- ther generic survey designs nor commonly accepted sur- vey contents exist. Many surveys combine quantitative and qualitative information-gathering: a review of recent MPO and statewide freight studies indicates that although freight surveys have been conducted, many of these are qualitative. The synthesis profiles 12 different types of freight trans- portation surveys: Roadside/intercept surveys1. Combined telephone/mail-back surveys2. Telephone interview surveys3. Mail-out/mail-back surveys4. Personal interview surveys5. Internet surveys6. Focus and stakeholder group surveys7. Commercial vehicle trip diary surveys8. GPS vehicle tracking surveys (more broadly, ITS 9. technologies) License plate match surveys—manual10. License plate match surveys—electronic11. Administrative surveys12.

63 Practitioners collected both qualitative and quantita-• tive information. To some extent, this distinction also determines the type of survey that can be used—some types can be used to collect both qualitative and quan- titative information, whereas others are usable for one or the other. Most practitioners indicated that they used external • data sets to enhance their own databases. Among 21 public and commercial data sources presented to sur- vey respondents, the U.S. DOT’s Freight Analysis Framework, the Commodity Flow Survey and the TRANSEARCH Insight Database were used most commonly. Most users found the external data sources to be “adequate” or “good.” Just over one-third of the practitioners (20 of 56 respon-• dents) used Intelligent Transportation Systems (ITS) technologies, with weigh-in-motion (WIM) technolo- gies and sensors being the most common application. Some practitioners found shortcomings in the available • freight data, whether their own data or from external sources. Specific shortcomings (in decreasing fre- quency of citation) included insufficient detail or inap- propriate scale (most commonly cited shortcoming, and common to several data sets); as well as high cost; incomplete coverage of the freight mode, movement, or commodity that is carried; datedness of the data; small sample size; incomplete geographical coverage; inadaptability of data developed for another purpose; and inapplicability of data definitions. Although practitioners identified several needs for • their freight surveys (see Needs and Gaps Identified in the Literature and Resultant Recommendations for Research in this chapter), they also noted several fac- tors for success in their data collection: Adequacy of funding (the single most dominant – theme) Prior knowledge and experience in both the conduct – of freight surveys and the analysis of the results, and among the actual surveyors Appropriate survey planning aimed at addressing – clearly specified objectives Effective communications with and engagement of – survey participants: related to this was the willing- ness of respondents to provide often-confidential information Adequacy of responses, including specificity and – level of detail Timeliness and currency of the data (i.e., ensuring – that the data are up to date and that they are pro- cessed quickly). Practitioners identified a range of costs for the conduct • of their surveys. However, the costs lack precision, in part because of the lack of a common understanding of what components of the survey the costs comprised, and also the accompanying difficulty in allocating costs among these components (and between external and internal resources). The survey was complemented by a literature review. Case studies for five survey types were identified, mainly from the United States but also from Canada and Europe. These comprised roadside/intercept surveys, focus and stakeholder group surveys, commercial trip diary surveys, establishment surveys, and ITS technologies. The range of case studies reflects a blend of the survey types that are used most commonly in practice, but also includes several research and comparison studies that reflect emerging prac- tice (i.e., in the use of ITS techniques). A sixth presentation describes the U.S. Commodity Flow Survey, which is differ- ent from the 12 categories of interest in this synthesis and, accordingly, was not taken into account otherwise. The pre- sentation also includes research studies on the comparison of techniques (notably, in the use of Global Positioning System (GPS), as well as summary descriptions of different survey techniques and applications. The case studies were used to present different aspects of or variations to a specific type of survey: the types of infor- mation gathered are described. In several cases, the descrip- tions are complemented by illustrations of sample survey forms; however, it is important to note that many surveys of a specific type are similar and the selection of illustrations is not exhaustive. Finally, the description is complemented by discussions on four key topics: survey costs, the use of ITS technologies, a comparison of survey types, and the Com- modity Flow Survey. NEEDS AND GAPS IDENTIFIED BY PRACTITIONERS AND RESULTANT RECOMMENDATIONS FOR RESEARCH A comprehensive survey of practitioners identified needs, current internal data collection efforts, usage of existing external public and commercial datasets, and an assessment of how well the internal and external data met users’ needs. The key needs and gaps, and the recommended associated research needs, are as follows: Despite the availability of many examples of sur-1. veys and information on the techniques for conduct- ing them, as well as several public freight data sets, respondents identified the need for the specifics of a vehicle trip (e.g., origin, destination, routing, ship- ment details, travel time, emissions) as the greatest need. This applied to all freight modes as well as intermodal freight movement. This suggests the fol- lowing research needs: The conduct of demonstration surveys, to serve two • purposes:

64 Comparing methods and demonstrating the – practical obstacles and opportunities to their use in actual field situations. As reported herein, comparisons between GPS and other methods have been conducted; however, more detail is required on the actual operational, financial, and other benefits and costs associated with each method. Recording the specific operational details of the – survey as it is being conducted. The survey of practitioners and the literature review for this Synthesis found that very little detailed informa- tion was available. This need is exemplified by the lack of detailed cost information. Particular attention should be given to recording detailed costs by survey activity throughout the demon- stration projects, given the difficulty in gather- ing this information from respondents after the survey. A detailed review of the efficacy of using existing • public freight data sets as the basis for capturing vehicle trip information. The review should exam- ine the feasibility of using these data sets as plat- forms for adding vehicle trip data as part of the data collection activity or for integrating separate vehi- cle trip surveys into them. The object of the review is to assess whether existing data sets could serve as practical, cost-effective means for providing the required data. Accordingly, the review should account for technical and statistical feasibility and integrity, and for practicality of use. Practitioners were more familiar with “traditional” 2. surveys, such as roadside/intercept surveys, than they were with ITS technologies. Moreover, insuffi- cient capital resources was cited as a barrier to further use of ITS technologies. This suggests the need for research into ways of further establishing the mon- etary benefits of and reducing the costs of new tech- nologies—in essence, the development of a “business case” for the introduction and application of ITS technologies, taking into account also the potential for emerging electronic technologies (perhaps being developed in other fields, not yet applied to trans- portation) to reduce costs, increase capabilities, and reduce processing time. Practitioners identified several ways to improve 3. deficiencies or gaps in their data collection. Most frequently cited, with greatest importance, were the need to provide more detail and ensure that data are collected regularly. This suggests that research should be conducted into the following approaches: The practical application of survey techniques • that are most effective in gathering the necessary details. Topics to be covered would include meth- ods to increase sample size, exploration of new or improved existing data sources to serve as sample frames, and post-survey data treatments to address confidentiality concerns and allow detailed data to be made available. The practical application of survey technologies to • gain precision and detail. This would examine the use of ITS technologies to record precise routings and travel times, as described earlier, as well as to speed or improve data processing and validation (e.g., through the use of personal digital assostants to enter data directly). The research also should examine ways to increase the level of detail, estab- lish a sufficient sample size to obviate confidential- ity concerns, and the like. Cost-effective and easily accessible survey • methods (i.e., survey design, sources for sample frames) that promote increased data collection fre- quency and regularity. The object is to find ways to reduce costs and make it easier for agencies to implement ongoing survey programs and expand geographic or modal coverage. The research also should examine practical examples of how DOTs and MPOs have developed and integrated multiple data collection and survey programs to build upon existing data collection capabilities and reduce unit costs. Methods that could reduce the processing, valida-• tion, and expansion time and costs required before survey results can be delivered. The usability and cost-effectiveness of ongoing or • more frequent survey instruments, to complement or replace “one-off” or infrequent surveys. Overall, practitioners cited the need to improve exist-4. ing surveys and capabilities. This suggests the need for— A detailed guide for the conduct of freight surveys, • with specific attention given to the practical consid- erations required for survey planning and conduct. The guide should be organized as a step-by-step guide, including the pre-survey preparation of required sample frames (because the experience of the Calgary survey demonstrates that compiling a directory of establishments can be an exercise in itself), sampling, institutional arrangements, inter- view techniques, post-survey processing, valida- tion and analysis, and reporting. Research on the design of survey questions to • improve clarity, precision, and accuracy in order to improve the quality of responses and increase responses rates. (The detailed guide should also address questionnaire design.) Research on the potential impact of new technolo-• gies and techniques to address legal and confiden- tiality issues.

65 Research on ways to build agency staff capabilities 5. by educating and training analysts, and on ways to disseminate the practical aspects of the conduct of surveys, from survey design, the development of appropriate sampling frames, and ensuring sufficient samples to provide necessary detail, to recruitment techniques, staff training, and specific details on sur- vey costs. Detailed documentation of all aspects of the survey process and its dissemination would be help- ful in improving the overall capabilities and resource pool among public agencies. NEEDS AND GAPS IDENTIFIED IN THE LITERATURE AND RESULTANT RECOMMENDATIONS FOR RESEARCH Researchers have identified several gaps: A 2008 United Kingdom study noted the need to “com- pare and validate” alternate techniques that could be used to gather the same type of information, in order to “determine the accuracy of each, and to investigate how both can poten- tially be enhanced to make up for any shortcomings they have” (55). The Portland, Oregon, and Peel Region, Canada, compar-1. isons of techniques are examples of this type of research (see Comparison of Techniques in chapter four). The surveys described herein are multifaceted and 2. generally are well established. However, they do not profile the characteristics of the complete supply chain involving the movement of a good from its true ori- gin to its ultimate destination. Rather, individual seg- ments of the chain tend to be captured. A 2007 review of freight data sources in Washington State identified the need to better understand the global supply chain and its manifestation in the movement of freight to, from, and within the state, as well as the workings of the distribution of goods produced in the state to domestic and international markets, and of the dis- tribution of products to the consumer (56). This also implies the development of a better understanding of cross-border and international commodity flows. A 2006 BESTUFS report identified the need to estab-3. lish indicators that assess the performance of goods movement. In addition, there is a need to address a lack of a “common understanding or agreement about what constitutes an urban [in this case] freight trans- port indicator” (57). A 2008 BESTUF report further identified the need to 4. develop common definitions and terms (58). OTHER RECOMMENDATIONS FOR RESEARCH Although not identified specifically by practitioners or in the literature, several other recommendations can be drawn from the findings: Development of a taxonomy of freight survey types, 1. common definitions, and a common set of indicators of performance. These fundamental categorizations will help guide any subsequent detailing and analy- sis of surveys. Throughout the literature and among practitioners, there is a lack of clarity regarding the differences between surveys and the techniques that are used to conduct them (e.g., “roadside/intercepts” are a type of survey; “telephone” is a technique used to conduct a survey). A useful taxonomy is provided by a 2008 United Kingdom study that identified 11 distinct types of quantitative and qualitative surveys and then discussed different techniques for conduct- ing them (57). Development of methods to improve the precision and 2. level of detail of existing surveys, notably through the integration of ITS technologies into the surveys. Further comparison and assessment of all aspects of 3. surveys, ranging from sample definition and selection to survey techniques and post-survey analysis. This comparison could be done through a series of pilot or site-specific tests, as exemplified by the research described in the preceding chapter. Development of data collection and survey methods 4. to detail the dynamics of the supply chain. Although this synthesis has touched on these, specific attention should be given to this emerging and somewhat diffi- cult-to-define subject.