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56 I N N O VAT I O N S I N T R AV E L D E M A N D M O D E L I N G , V O L U M E 1 ment of Transportation (CDOT), the FasTracks rapid ables and interactions than conventional trip-based transit ballot initiate, and DRCOG's MetroVision Plan. models. Trip-based models tend to be relatively insensi- DRCOG conducted the IRM vision phase to ensure tive to many input data changes and do not include that the new model would address the Denver Region enough detail to respond fully to these changes. Activity- MetroVision Plan. The vision phase included an evalua- based models are expected to provide improved fore- tion of other advanced modeling projects in North Amer- casting for various types of policy analysis. ica and Europe. A panel composed of modeling experts, One advantage of activity-based models is that mod- regional planners and engineers, and regional policy mak- eling individuals in the synthetic population allows for dis- ers provided guidance throughout the model develop- tributed values of time rather than fixed values for a ment process. The vision phase identified the top 10 core relatively small number of market segments. For example, planning issues that the travel demand model should sup- if the value of time is $12 an hour for a specific geographic port. These core planning issues included (a) the effects of market to find using a toll road desirable, and the average development patterns on travel behavior, (b) the sensitiv- value of time for that market segment is $10 an hour, the ity to price and behavioral change, (c) the effects of the model would estimate that no one from that market seg- transportation system and system condition, (d) ment would use the facility. If value of time distribution improved validity and reliability, (e) the ability to evalu- were used with an average value of $10 an hour with a ate policy initiatives, (f) better analysis of freight move- 20% probability of having a value of time greater than ments, (g) the ability to evaluate environmental effects, $12 an hour, there would be demand estimated for the (h) the ability to model low-share alternatives, (i) an market segment. Demand for toll roads with tolls varying enhanced ability to evaluate the effects on specific popu- by time of day can also be modeled more accurately. lation subgroups, and (j) the ability to reflect intelligent There are also benefits to modeling travel to urban transportations system and transportation demand man- centers and transit-oriented development from use of the agement and other nonsystem policy changes. proposed activity-based approach. Activity-based mod- The CTE, which was established by the state legis- els permit descriptions of individuals using a richer set of lature within CDOT, has been analyzing corridors in the variables than traditional models. The tour-based Denver area for potential toll facilities. Six possible cor- approach also captures the effects of trip chaining. Dis- ridors have been identified to date. The need for a new aggregate models can accommodate more demographic activity-based model to analyze toll facilities was identi- variables than traditional models. fied as important in the IRM vision phase. Toll options The proposed activity-based approach appears are also being considered in several environmental practical. It greatly enhances sensitivity to triptour impact statements under way in the region. interactions and provides improved demographic The FasTracks ballot initiative, which was detail, geographic detail, and interaction between approved by voters in 2004, includes approximately 130 model components. There are some limits with the pro- miles of rapid transit. The FasTracks projects are sched- posed approach, however. A conventional static traffic uled to be completed by 2017. The ability for the new assignment process will be used. The lack of a fully dis- model to evaluate the impacts of the FasTracks system aggregate or at least a dynamic traffic assignment pro- was identified as important in the IRM vision phase. cedure will limit the ability to analyze the effects of The ability to analyze the effects of the MetroVi- traffic queuing and variations of traffic flow within sion Urban Growth Boundary was also identified as an peak periods. Even with these limitations, the new important feature for the new model. Approximately model will greatly enhance travel forecasting in the 750 square miles are included inside the 2030 urban Denver area. growth boundary. The need to expand the boundary to accommodate forecast growth will be examined as part of the MetroVision 2035 process. HARDWARE REQUIREMENTS AND RUNNING There is also a need to model the effects of the TIME FOR THE MID-OHIO REGIONAL MetroVision urban centers and transit-oriented develop- PLANNING COMMISSION TRAVEL ments, which are intended to foster a more balanced FORECASTING MODEL transportation system. The MetroVision 2030 plan includes approximately 70 centers. Other needed model Rebekah Anderson, Zhuojun Jiang, and capabilities include the ability to assess air quality and Chandra Parasa environmental impacts, as well as lower-density develop- ment patterns and traditional highway projects. Rebekah Anderson discussed the model formulation, the Activity-based models would be expected to pro- hardware requirements, and the running times for the duce more accurate results for policy analysis because Mid-Ohio Regional Planning Commission (MORPC) these models are able to consider a wider range of vari- disaggregate tour-based travel model. Volume 2 includes