Freight Transportation Surveys (2011)

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SUMMARY FREIGHT TRANSPORTATION SURVEYS The efficient movement of freight is important for local, state, and even national economic viability. Understanding the movement of freight and of its characteristics is essential to promoting efficiency and economic development. A need exists to examine the different methods, techniques, and results of current efforts to survey and collect data on freight transportation. This information can take many forms, from classified traffic counts and travel time studies to comprehensive commodity flow and origin-destination surveys. However, it can be challenging to collect such information because of the complexity of the demand for freight transportation. Several factors contribute to this complexity. For example, urban freight transportation factors include the number and varying characteristics of the decision makers, the diversity in the types of goods (i.e., commodities) carried, origin-destination and routing patterns, freight costs, units of measure, and the activities that take place in an urban area. The sup- ply chain involves a number of decision makers in both the public and private sectors: the former as providers and owners of freight infrastructure and services and as regulators, and the latter as shippers, carriers, and distributors of goods. Finally, the movement of freight can involve several transportation modes, intermediate transfer and processing facilities, and jurisdictions. The large range of freight survey practices reflects the complexity of freight demand and the multiplicity of influencing factors and supply chain participants. This synthesis profiles the state of the practice in methods and techniques used to survey and collect data on freight transportation. Based on the profile, the synthesis identifies important issues, identifies gaps in knowledge, and identifies areas for potential future research. Although the focus is on data that are gathered for modeling, surveys for other applications also are considered—for example, qualitative surveys on freight planning issues. The focus was on road-based freight transportation, although surveys and data on other modes also are included. Both urban and inter-urban surveys and data are considered. The following 12 different types of surveys are profiled in the synthesis: 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.

2 Commercial vehicle trip diary surveys8. Global Positioning System (GPS) vehicle tracking surveys [more broadly, Intelligent 9. Transportation System (ITS) technologies] License plate match surveys—manual10. License plate match surveys—electronic11. Administrative surveys12. The synthesis describes practices in each type of survey. Several are illustrated by case studies. The description is complemented by discussions on four key topics: survey costs, the use of ITS technologies, a comparison of survey types, and the Commodity Flow Survey. A web-based survey of practitioners was the primary source of information for the syn- thesis. The survey solicited information on several topics, including survey costs, practi- tioners’ 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 survey was sent to all state departments of transportation (DOTs), as well as to selected metropolitan planning organizations that were known to be active in recent freight planning activities. 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. State DOTs provided the greatest number of responses (46). This number includes three DOTs that did not participate in the web-based survey but indicated separately that they are not involved in freight surveys (i.e., the subject was “not applicable” to them). This number also includes responses from two different offices of the California DOT, which chose to respond separately: in the ensuing discussion of the results, the two responses have been combined only where appropriate. Each of the other sampled agencies responded only once. The greatest rate of return was represented by the 45 state DOT respondents, at 88% of the 51 DOTs. Overall, 55 of the solicited agencies responded, for a response rate of 74%. Table 1 presents the rates of return by agency type. TABLE 1 RATE OF RETURN BY AGENCY Agency Number of Surveys Sent Number of Surveys Returned Number of Nonapplicable Responses Total Number of Responses Rate of Return State DOTs 51 43 3 46 88%* MPOs 15 8 0 8 53% Marine Port/Airport Authority 2 2 0 2 100% Federal Agency 2 0 0 0 0% Academic 1 0 0 0 0% Commercial Data Purveyor 2 0 0 0 0% Other 1 0 0 0 0% Total 74 52 4 56 74%* *Rates reflect 45 state DOTs, as two individual offices from the California Department of Transportation responded.

3 The results provided a wide range of responses to virtually 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 findings 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; however, 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, including speed and emission data. Among the 12 types of surveys, roadside/intercept surveys (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. Practitioners collected both qualitative and quantitative information. To some extent • this distinction also determines the type of survey that can be used (i.e., some types can be used to collect both qualitative and quantitative information, whereas others are usable for one or the other). Most practitioners indicated that they used external data sets (provided by others) • to enhance their own databases. Among 21 public and commercial data sources presented to survey respondents, the U.S. DOT’s Freight Analysis Framework, the Commodity Flow Survey, and the TRANSEARCH Insight Database were most com- monly used. Most users found the external data sources to be “adequate” or “good.” Just over one-third of the practitioners (20 of 56 respondents) used ITS technolo-• gies, with weigh-in-motion technologies and sensors being the most common applications. Some practitioners found shortcomings in the available freight data, whether their • own data or from external sources. Specific shortcomings (in decreasing frequency of citation) included insufficient detail or inappropriate scale (most commonly cited shortcoming, and common to several data sets), as well as high cost, incomplete cov- erage of the freight mode, movement or commodity that is carried, datedness of the data, small sample size, incomplete geographical coverage, inadaptability of data that had been developed for another purpose, and inapplicability of the data definitions. Practitioners identified several needs for their freight surveys (see “Needs and Gaps • Identified by Practitioners” and “Resultant Recommendations for Research” in chap- ter five) and also noted several factors for success in their collection of freight data: Adequacy of funding (the 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 willingness 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 processed 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 the accompanying diffi- culty in allocating costs among these components (and between external and internal resources).

4 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 stud- ies 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 practice (i.e., in the use of ITS techniques). A sixth presentation describes the U.S. Commodity Flow Survey, which is different from the 12 categories of interest in this synthesis and, accordingly, was not taken into account otherwise. The presentation also includes research studies on the comparison of techniques (notably, the use of GPS), as well as summary descriptions of dif- ferent survey techniques and applications. The case studies were used to present different aspects of or variations to a specific type of survey: they describe the types of information gathered. In several cases, the descriptions are complemented by illustrations of sample survey forms; however, it is important to note that many surveys of a specific type are similar to each other and the selection of illustrations is not exhaustive. 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 recom- mended associated research needs are as follows: Despite the availability of many examples of surveys and information on the tech-1. niques for conducting them, as well as several public freight data sets, respondents identified the greatest need as more information on the specifics of a vehicle trip (ori- gin, destination, routing, shipment details, travel time, emissions, etc.). 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 compare methods and demonstrate their a. practical opportunities and obstacles in actual field situations, as well as to record the operational details of the survey in progress. A detailed review of the efficacy of using existing public freight data sets as the b. basis for capturing vehicle trip information. More research is needed into ways of further establishing the monetary benefits of 2. new ITS technologies and of reducing the costs of new technologies. Practitioners identified several ways to improve data collection deficiencies or gaps. 3. Most frequently cited, with greatest importance, were the need to provide more detail and the need to ensure that data are collected regularly. This suggests that research should be conducted into— The practical application of survey techniques that are most effective in gathering a. the necessary details; for example, methods 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 The practical application of survey technologies to gain precision and detailb. Survey methods (i.e., survey design, sources for sample frames, etc.) that are c. cost-effective and easily accessible, in order to promote increased data collection frequency and regularity Methods that could reduce the processing, validation, and expansion time and costs d. required before survey results can be delivered The usability and cost-effectiveness of ongoing or more frequent survey e. instruments, to complement or, if appropriate, replace “one-off” or infrequently conducted surveys.

5 Overall, practitioners cited the need to improve existing surveys and capabilities. 4. This suggests the need for— A detailed guide for the conduct of freight surveys, with specific attention given a. to the practical considerations required for survey planning and conduct Research on the design of survey questions to improve clarity and accuracy b. Research on the potential impact of new technologies and techniques to address c. legal and confidentiality issues. Research on ways to build agency staff capabilities by educating and training 5. analysts. Researchers also identified several gaps: The need to “compare and validate” alternate techniques that could be used to gather 6. the same type of information in order to “determine the accuracy of each, and to investigate how both can potentially be enhanced to make up for any shortcomings they have.” The need to better understand the global supply chain and its manifestation in the 7. 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 distribution of products to the consumer. The need to establish indicators; that is, to specify measures to assess the perfor-8. mance of goods movement. In addition, there is a need to address a lack of a “com- mon understanding or agreement about what constitutes an urban [in this case] freight transport indicator.” Although not identified specifically by practitioners or in the literature, several other recommendations can be drawn from the findings: Develop a taxonomy of freight survey types, common definitions, and a common set 9. of indicators of performance. Develop methods to improve the precision and level of detail of existing surveys, 10. notably through the integration of ITS technologies into the surveys. Compare and assess all aspects of surveys, from sample definition and selection to 11. survey techniques and post-survey analysis. This comparison could be done through a series of pilot or site-specific tests.