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Modeling Travel and Transport in Vermont
- By Ben Carlson
TRC Research Analyst Jim Sullivan works on the Vermont Travel Model for VTrans, using modeling software to examine the effects of changes to the transportation system. This includes addressing such questions as the impacts of changes in population and economic activity on the transportation network. By providing this knowledge, the model allows effective transportation planning and investment across the state.
Managing the statewide model includes keeping it up to date with the most recent population, employment, and travel behavior information. Recently, the model has been updated from a base year of 2000 to 2010, meaning the model now contains data from the 2010 Census and the 2009 National Household Travel Survey. Adjusting the population in the model to reflect the most current information increases the accuracy of modeling done in the future by better reflecting the number and behavior of travelers in different parts of the state.
Research Analyst Jim Sullivan (left) and Researcher Matt Conger with the Vermont Travel Model
TRC Researcher Matt Conger will also begin working on the model after recently returning from visiting Caliper, the developer of TransCAD, in Newton, Massachusetts. At Caliper, he took part in an intensive training seminar in preparation to join Sullivan as part of the TRC Team working on the statewide model. Conger’s training will allow him to work on improving the model, as well as applying changes in the transportation system to estimate the implications for projected land and road use. Conger looks forward to using his training in Discrete Choice Modeling (DCM) in future projects at the TRC. Conger explains, “Discrete choice modeling (DCM) allows the user to predict the travel mode choice of each trip purpose undertaken based upon the estimated 'utility' of each of the available modes - passenger vehicle, carpool, transit, bicycling and walking, for example.” Further, Conger’s training in Transit Routing allows the modeling of public transit travel in a host of TRC projects to be improved. As Conger notes, “These two TransCAD modules offer important tools in forecasting the effects of changes in infrastructure and land use patterns upon travel behaviors.”
Recently, the statewide model was used to examine the impacts of a bypass around Morrisville, VT to move traffic from the north and south around the congested Village Corridor. An analysis was originally conducted in 2002 using the statewide model, but that analysis needed to be updated in 2011 before the project could move forward. The updated analysis examined the results of building vs. not building the bypass, forecasting the impacts of each scenario 20 years into the future. Several of the 2002 results were revised due to the improvement of the updated model. The study found that traffic would be reduced almost 80 percent in the village center due to use of the by-pass route, an area which currently faces significant congestion issues. For the 20-year forecast, the construction of the bypass is expected to increase future settlement near the route, but growth would be lower elsewhere in the town. Without the change, the downtown corridor may reach its capacity in the evening peak for travel, as the already congested area faces increasing traffic.
Image: Travel Model for Morrisville Village
These findings were of particular interest to Amanda Holland, a land-use planner at the Lamoille County Planning Commission who worked on this project. Holland is also currently pursuing the Sustainable Transportation Graduate Certificate from the TRC and enrolled in the course “Critical Issues in Transportation in the 21st Century”. “The model was useful in showing the potential flow of traffic after the truck route is built”, said Holland, “and the expected reduction in volumes that could potentially allow for some design changes along the existing route”. Holland noted the seriousness of the current and forecasted congestion, which is especially troublesome for businesses that rely on freight traveling to and from the interstate efficiently. The modeling results also contributed to the Morristown North End Business District Circulation Study by Resource Systems Group, Inc. (RSG), which showed that several intersections had a level of service (LOS) of D or F, which would improve due to the reduction in traffic if the bypass is built.
This partnership with VTrans also has involved other work, such as examining whether national studies are relevant to Vermont. For example, a recent national study by Frontier Group for the U.S. PIRG Education Fund noted many new trends among younger drivers, between 16 and 34 years of age. Using the National Household Travel Survey (NHTS) data from 2001 and 2009, Sullivan found that only some of these national trends (6 of 16) held true for younger Vermonters. These included changes such as reduced vehicle miles traveled and trips, as well as more use of travel options. While 7 of the trends could not be fully assessed due to data constraints, 3 of the topics showed the reverse of the national report’s findings. Vermonters are taking fewer walking and transit trips, rather than more, and overall length of trips has grown, rather than shrunk. This research provides essential information to policy makers in Vermont, providing accurate data on transportation patterns over time in the state. Policy and action can be informed through the use of these data sources to examine national findings and their assumptions to accurately determine the conditions in Vermont.
The potential opportunities for applying the statewide model in the future are numerous, as this model can examine the impacts of new transportation projects as well as growth and decline in population and employment around the state. The newly proposed development in the Northeast Kingdom, for example, provides an opportunity to use the model to examine the effects of these large changes to the area. The Northeast Kingdom Economic Development Initiative (NKEDI) will create many opportunities and many challenges, including the major issue of transportation, from building sufficient infrastructure to ensuring that the new systems promote development that is consistent with regional plans. The statewide model could prove especially useful for these challenges by evaluating and comparing various scenarios for development, new road construction, capacity expansion, and the effects of disruptions to the road network like heavy snowfall. This type of evaluation could allow the best planning decisions for the project moving forward with these major investments.
The TRC looks forward to opportunities to continue to work with VTrans, developers, Regional Planning Commissions, and Vermont communities on the many challenging issues facing the state. The TRC anticipates being involved in analyses of transit suitability, roadway vulnerability, freight movement efficiency and positioning of the transportation workforce.