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38 CHAPTER four CASE STUDIES INTRODUCTION vey results. Some modifications were made to address the specific requirements of the GDOT truck lanes study, and to This chapter presents case studies for several types of sur- capture data on commodity type and category. The collected veys. The presentation complements the findings of the data comprised-- practitioners' survey that were described in chapter three with details of actual surveys and their characteristics. The · Vehicle information: number of axles, number of units, details are taken from material provided by practitioners and truck configuration, trailer style, hazardous materials from the literature. In addition, the last section presents a status, and state of registration. comparison of surveys from the literature. · Trip information: origin, destination, frequency, roads use, purpose, origin facility type, destination facility It should be noted that the surveys are presented in two type, load status, commodity type, routing decision- ways, depending on the type of survey and on the availability maker (who chooses the route), and load type/vehicle of source material. Case studies are presented individually ownership. for some survey types, and in others surveys are combined in order to exemplify specific points. In all cases, for a given A shorter questionnaire was used for the two Port of survey type each of the surveys included presents a different Savannah surveys to expedite data collection and to allow aspect or variation. for localized differences in truck origin-destination patterns. Some port-specific questions also were included. ROADSIDE/INTERCEPT SURVEYS Of particular note is the use of a PDA for both surveys. The PDA allowed for direct entry of the data into an electronic Statewide Truck Lanes Needs Identification Study-- database and the automatic data coding. This reduced costs Georgia by avoiding manual data entry and coding and increased accuracy by reducing the likelihood of key entry errors after The Georgia Department of Transportation (GDOT) con- the fact. ducted a series of roadside origin-destination surveys in 2006 as part of a statewide study to identify the need for The survey had four types of questions: truck lanes. The surveys were conducted at eight weigh stations along high-volume truck Interstate highways. The · Choose one (e.g., the location at which the survey was locations were also selected to provide a geographic distribu- conducted) tion across the state, and to avoid duplication with a similar · Choose multiple (e.g., trailer style) survey that was conducted just prior to the GDOT surveys · Text entry (e.g., description of the location at which the by the Atlanta Regional Council (ARC) in and around the trip originated) Atlanta metropolitan area. Surveys also were conducted at · Numeric entry (e.g., number of axles). two gates to the Port of Savannah, given the high volume of truck traffic to and from that area. Figure 2 presents example of these questions. Note that some of the questions require input from the driver and oth- Twenty-four hour counts were conducted at the same time ers are based only on the interviewer's observations (4). as the surveys. These were used as the basis for expanding the samples at each site. A total of 3,636 trucks was sampled Portland Freight Data Collection Program--Port of at the 10 sites: these represented between 4.0% and 15.8% of Portland et al. the daily truck volumes at the weigh station sites and 14.9% and 18.3% at the Port of Savannah gates. In 2005, a comprehensive freight data collection program was initiated in the metropolitan Portland, Oregon, region. The GDOT survey was based on the ARC survey in order The data were collected on behalf of the Port of Portland, to further coordinate efforts and facilitate the sharing of sur- the Oregon Department of Transportation, the Washington