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63 · Practitioners collected both qualitative and quantita- costs among these components (and between external tive information. To some extent, this distinction also and internal resources). determines the type of survey that can be used--some types can be used to collect both qualitative and quan- The survey was complemented by a literature review. titative information, whereas others are usable for one Case studies for five survey types were identified, mainly or the other. from the United States but also from Canada and Europe. · Most practitioners indicated that they used external These comprised roadside/intercept surveys, focus and data sets to enhance their own databases. Among 21 stakeholder group surveys, commercial trip diary surveys, public and commercial data sources presented to sur- establishment surveys, and ITS technologies. The range vey respondents, the U.S. DOT's Freight Analysis of case studies reflects a blend of the survey types that are Framework, the Commodity Flow Survey and the used most commonly in practice, but also includes several TRANSEARCH Insight Database were used most research and comparison studies that reflect emerging prac- commonly. Most users found the external data sources tice (i.e., in the use of ITS techniques). A sixth presentation to be "adequate" or "good." describes the U.S. Commodity Flow Survey, which is differ- · Just over one-third of the practitioners (20 of 56 respon- ent from the 12 categories of interest in this synthesis and, dents) used Intelligent Transportation Systems (ITS) accordingly, was not taken into account otherwise. The pre- technologies, with weigh-in-motion (WIM) technolo- sentation also includes research studies on the comparison of gies and sensors being the most common application. techniques (notably, in the use of Global Positioning System · Some practitioners found shortcomings in the available (GPS), as well as summary descriptions of different survey freight data, whether their own data or from external techniques and applications. sources. Specific shortcomings (in decreasing fre- quency of citation) included insufficient detail or inap- The case studies were used to present different aspects of propriate scale (most commonly cited shortcoming, or variations to a specific type of survey: the types of infor- and common to several data sets); as well as high cost; mation gathered are described. In several cases, the descrip- incomplete coverage of the freight mode, movement, tions are complemented by illustrations of sample survey or commodity that is carried; datedness of the data; forms; however, it is important to note that many surveys of small sample size; incomplete geographical coverage; a specific type are similar and the selection of illustrations is inadaptability of data developed for another purpose; not exhaustive. Finally, the description is complemented by and inapplicability of data definitions. discussions on four key topics: survey costs, the use of ITS · Although practitioners identified several needs for technologies, a comparison of survey types, and the Com- their freight surveys (see Needs and Gaps Identified modity Flow Survey. in the Literature and Resultant Recommendations for Research in this chapter), they also noted several fac- tors for success in their data collection: NEEDS AND GAPS IDENTIFIED BY PRACTITIONERS Adequacy of funding (the single most dominant AND RESULTANT RECOMMENDATIONS FOR theme) RESEARCH Prior knowledge and experience in both the conduct of freight surveys and the analysis of the results, and A comprehensive survey of practitioners identified needs, among the actual surveyors current internal data collection efforts, usage of existing Appropriate survey planning aimed at addressing external public and commercial datasets, and an assessment clearly specified objectives of how well the internal and external data met users' needs. Effective communications with and engagement of The key needs and gaps, and the recommended associated survey participants: related to this was the willing- research needs, are as follows: ness of respondents to provide often-confidential information 1. Despite the availability of many examples of sur- Adequacy of responses, including specificity and veys and information on the techniques for conduct- level of detail ing them, as well as several public freight data sets, Timeliness and currency of the data (i.e., ensuring respondents identified the need for the specifics of a that the data are up to date and that they are pro- vehicle trip (e.g., origin, destination, routing, ship- cessed quickly). ment details, travel time, emissions) as the greatest · Practitioners identified a range of costs for the conduct need. This applied to all freight modes as well as of their surveys. However, the costs lack precision, in intermodal freight movement. This suggests the fol- part because of the lack of a common understanding of lowing research needs: what components of the survey the costs comprised, · The conduct of demonstration surveys, to serve two and also the accompanying difficulty in allocating purposes:
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64 Comparing methods and demonstrating the ods to increase sample size, exploration of new or practical obstacles and opportunities to their improved existing data sources to serve as sample use in actual field situations. As reported herein, frames, and post-survey data treatments to address comparisons between GPS and other methods confidentiality concerns and allow detailed data to have been conducted; however, more detail is be made available. required on the actual operational, financial, · The practical application of survey technologies to and other benefits and costs associated with each gain precision and detail. This would examine the method. use of ITS technologies to record precise routings Recording the specific operational details of the and travel times, as described earlier, as well as to survey as it is being conducted. The survey of speed or improve data processing and validation practitioners and the literature review for this (e.g., through the use of personal digital assostants Synthesis found that very little detailed informa- to enter data directly). The research also should tion was available. This need is exemplified by examine ways to increase the level of detail, estab- the lack of detailed cost information. Particular lish a sufficient sample size to obviate confidential- attention should be given to recording detailed ity concerns, and the like. costs by survey activity throughout the demon- · Cost-effective and easily accessible survey stration projects, given the difficulty in gather- methods (i.e., survey design, sources for sample ing this information from respondents after the frames) that promote increased data collection fre- survey. quency and regularity. The object is to find ways · A detailed review of the efficacy of using existing to reduce costs and make it easier for agencies to public freight data sets as the basis for capturing implement ongoing survey programs and expand vehicle trip information. The review should exam- geographic or modal coverage. The research also ine the feasibility of using these data sets as plat- should examine practical examples of how DOTs forms for adding vehicle trip data as part of the data and MPOs have developed and integrated multiple collection activity or for integrating separate vehi- data collection and survey programs to build upon cle trip surveys into them. The object of the review existing data collection capabilities and reduce is to assess whether existing data sets could serve unit costs. as practical, cost-effective means for providing · Methods that could reduce the processing, valida- the required data. Accordingly, the review should tion, and expansion time and costs required before account for technical and statistical feasibility and survey results can be delivered. integrity, and for practicality of use. · The usability and cost-effectiveness of ongoing or more frequent survey instruments, to complement 2. Practitioners were more familiar with "traditional" or replace "one-off" or infrequent surveys. surveys, such as roadside/intercept surveys, than they were with ITS technologies. Moreover, insuffi- 4. Overall, practitioners cited the need to improve exist- cient capital resources was cited as a barrier to further ing surveys and capabilities. This suggests the need use of ITS technologies. This suggests the need for for-- research into ways of further establishing the mon- · A detailed guide for the conduct of freight surveys, etary benefits of and reducing the costs of new tech- with specific attention given to the practical consid- nologies--in essence, the development of a "business erations required for survey planning and conduct. case" for the introduction and application of ITS The guide should be organized as a step-by-step technologies, taking into account also the potential guide, including the pre-survey preparation of for emerging electronic technologies (perhaps being required sample frames (because the experience of developed in other fields, not yet applied to trans- the Calgary survey demonstrates that compiling a portation) to reduce costs, increase capabilities, and directory of establishments can be an exercise in reduce processing time. itself), sampling, institutional arrangements, inter- view techniques, post-survey processing, valida- 3. Practitioners identified several ways to improve tion and analysis, and reporting. deficiencies or gaps in their data collection. Most · Research on the design of survey questions to frequently cited, with greatest importance, were the improve clarity, precision, and accuracy in order need to provide more detail and ensure that data are to improve the quality of responses and increase collected regularly. This suggests that research should responses rates. (The detailed guide should also be conducted into the following approaches: address questionnaire design.) · The practical application of survey techniques · Research on the potential impact of new technolo- that are most effective in gathering the necessary gies and techniques to address legal and confiden- details. Topics to be covered would include meth- tiality issues.