The National Academies Press

Currently Skimming:

Pages 1-16

The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.

From page 1... ... Page 1 of 23 May 10, 2004 The Honorable Christopher Zimmerman Chairman National Capital Region Transportation Planning Board Metropolitan Washington Council of Governments 777 North Capitol Street, NE, Suite 300 Washington, DC 20002 Dear Chairman Zimmerman: This letter is the second report of the Transportation Research Board's (TRB's) Committee for Review of Travel Demand Modeling by the Metropolitan Washington Council of Governments (MWCOG) Read the entire page →
From page 2... ... Page 2 of 23 The committee's initial letter report, dated September 8, 2003, addressed the first two items.2 This second letter addresses the last three items and other matters raised in a work program document that TPB presented to the committee. That document is included here as Attachment 4.3 In the course of preparing this report, committee members met as a group several times by teleconference and held a face-to-face meeting and teleconferences with TPB staff. Read the entire page →
From page 3... ... Page 3 of 23 estimate air pollution emissions and other aspects of the region's well-being. These new models, the committee agrees, are likely to be used widely within the next decade. Read the entire page →
From page 4... ... Page 4 of 23 important modeling parameters, large surveys can be expensive. For the purposes of model calibration, surveys that incorporate selective sampling of stratified populations can be more effective and efficient than those that entail larger random samples. Read the entire page →
From page 5... ... Page 5 of 23 The document also poses a number of questions soliciting the committee's advice on several matters concerning modeling strategy and data collection. The following sections present the committee's findings and conclusions, first on the points of concern raised in the committee's initial report and addressed in the work program document and second on TPB's questions. Read the entire page →
From page 6... ... Page 6 of 23 procedures in postprocessing for estimating hourly highway traffic volumes and speeds. The committee considers each of these areas in turn. Read the entire page →
From page 7... ... Page 7 of 23 The committee agrees that these enhancements, along with the longer-term recalibration and restructuring of the agency's mode choice model, should yield benefits. Overall, these various efforts to improve model validation are commendable. Read the entire page →
From page 8... ... Page 8 of 23 committee surmises that some truck count data currently available in the MWCOG study area7 would allow work on the truck and commercial vehicle trip tables to begin before additional classification counts are collected. The committee recommends that preliminary work be scheduled to examine the availability and coverage of truck counts, to support early updating of the TPB truck and commercial vehicle trip tables. Read the entire page →
From page 9... ... Page 9 of 23 effort and agrees that the work should continue. The second type of work TPB proposes is a sensitivity analysis to investigate whether the use of factors can be reduced. Read the entire page →
From page 10... ... Page 10 of 23 abundantly applied to other intercounty links. Speed Feedback Incorporating Mode Choice The committee commented in its first report that TPB's feedback of highway and transit times to trip distribution bypasses mode choice and is not typical of good modeling practice in regions with significant transit services and ridership. Read the entire page →
From page 11... ... Page 11 of 23 interchange than to calculate an origin-destination composite time that weights the transit time by the regional transit mode share. The former approach should increase the model's sensitivity to transit improvements by increasing the importance of transit in trip distribution for those interchanges with a high transit mode share while reducing its importance for those interchanges with negligible transit trips. Read the entire page →
From page 12... ... Page 12 of 23 volume within a time period sum to 100 percent) Read the entire page →
From page 13... ... Page 13 of 23 The work of these early adopters will benefit the profession as a whole as well as the stakeholders in those specific agencies' travel demand forecasting. The committee recommends that TPB actively monitor the early adopters' progress and appreciates TPB's efforts to learn more about such models. Read the entire page →
From page 14... ... Page 14 of 23 questions are important in this context. TPB staff might gain insights by reviewing the literature on the topic.15 Travel Surveys and Other Data for Travel Modeling The scope of work presented to the committee at the start of the study called for commentary on travel survey and other data needed for future TPB model upgrades. Read the entire page →
From page 15... ... Page 15 of 23 stratified and choice-based sampling will be appropriate strategies for addressing this problem. Sampling Households Outside Planning Area TPB asked whether there a "compelling need" to collect a minimum number of household samples for jurisdictions that are modeled but are beyond the TPB planning area. Read the entire page →
From page 16... ... Page 16 of 23 We nevertheless find the RDD sample frame to be a practical way of coupling household surveys with the computer-assisted telephone interview. The committee proposes that TPB explore recent applications of other survey design and recruitment methods. Read the entire page →

From page 1...

... Page 1 of 23 May 10, 2004 The Honorable Christopher Zimmerman Chairman National Capital Region Transportation Planning Board Metropolitan Washington Council of Governments 777 North Capitol Street, NE, Suite 300 Washington, DC 20002 Dear Chairman Zimmerman: This letter is the second report of the Transportation Research Board's (TRB's) Committee for Review of Travel Demand Modeling by the Metropolitan Washington Council of Governments (MWCOG)