Timothy F. Welch

A Joint Travel Demand and Environmental Model to Incorporate Emission Pricing for Large Transportation Networks

Authors: Sabyasachee Mishra and Timothy F. Welch (2011)
Report
Synopsis: Emission reduction strategies are gaining greater attention to support the national objective for a sustainable and green transportation system. A large percent of emission contribution arises from transportation modes are primarily from auto and truck travel. Reductions in highway travel require prudent planning strategies and modeling user’s response to planner’s policies. Modeling planning goals and user’s response is a challenging task. In this paper the authors present a joint travel demand and environmental model to incorporate vehicle emission pricing (VEP) as a strategy for emission reduction. First, the travel demand model determines the destination, mode and route choice of the user’s in response to the VEP strategy set by the planner. Second, the emission model provides NOx, VOC, and CO2 estimates at a very detailed level. A Base-case and three models are proposed to incorporate VEP in a multimodal transportation network. The objective function of the Base-case is the minimization of Total System Travel Time (TST), and the models are designed with the objective of minimizing of Total System Emission (TSE). User Equilibrium method is used for travel to model user responses and solved by Frank Wolfe algorithm. The Base-case represents “do-nothing” conditions and the three models address the interactions between planner’s perspectives and user responses to VEP strategies. The proposed model is applied to Montgomery County’s (located in the Washington DC-Baltimore region) multimodal transportation network. The case study results show that VEP can be used as a tool for emission reduction in transportation planning and policy.

 

Even Smarter Growth? Land Use, Transportation, and Greenhouse Gas in Maryland

Authors: Avin, Uri, Timothy F. Welch, Gerrit Knaap, Fred Ducca, Sabyasachee Mishra, Yuchen Cui, and Sevgi Erd
Report
Synopsis: Urban form studies have generally used regional density vs. sprawl land use scenarios to assesstravel behavior outcomes. The more nuanced but nonetheless important allocation of jobs andhousing and their relationship to each other as a factor in travel behavior has received much lessattention. That relationship is explored in this statewide urban form study for Maryland. This is astate where county land use has a long tradition of growth management, but one whose regionaland statewide implications have not been evaluated. How does a continuation of the County levelsmart growth regime play out statewide compared to other scenarios of job and housingdistribution that are driven by higher driving costs or transit oriented development goals or localzoning rather than local policy-driven projections? Answers are provided through the applicationof a statewide travel demand model, the Maryland Statewide Transportation Model (MSTM).The findings suggest that the debate should move beyond walkability, density and compactgrowth and towards a more productive dialog about how we organize whole cities and regions.

 

A Joint Travel Demand and Environmental Model To Incorporate Emission Pricing For Large Transportation Networks

Authors: Sabyasachee Mishra and Timothy Welch (2012)
Report
Synopsis: Emission reduction strategies are gaining greater attention to support the national objective for a sustainable and green transportation system. A large percent of emission contribution that arises from transportation modes are primarily from auto and truck travel. Reductions in highway travel require prudent planning strategies and modeling user’s response to planner’s policies. Modeling planning goals and user’s response is a challenging task. In this paper the authors present a joint travel demand and environmental model to incorporate vehicle emission pricing (VEP) as a strategy for emission reduction. First, the travel demand model determines the destination, mode and route choice of the users in response to the VEP strategy set by the planner. Second, the emission model provides NOx, VOC, and CO2 estimates at a very detailed level. A Base-case and three models are proposed to incorporate VEP in a multimodal transportation network. The objective function of the Base-case is the minimization of Total System Travel Time (TST), and the models are designed with the objective of minimizing Total System Emission (TSE). User Equilibrium method is used for travel to model user responses and solved by Frank Wolfe algorithm. The Base-case represents “do-nothing” conditions and the three models address the interactions between planner’s perspectives and user responses to VEP strategies. The proposed model is applied to Montgomery County’s (located in the Washington DC-Baltimore region) multimodal transportation network. The case study results show that VEP can be used as a tool for emission reduction in transportation planning and policy.

 

Performance Indicators for Public Transit Connectivity in Multi-Modal Transportation Networks

Authors: Sabyasachee Mishra, Timothy Welch, and Manoj K. Jha (2012)
Report
Synopsis: Connectivity plays a crucial role as agencies at the federal and state level focus on expanding the public transit system to meet the demands of a multimodal transportation system. Transit agencies have a need to explore mechanisms to improve connectivity by improving transit service. This requires a systemic approach to develop measures that can prioritize the allocation of funding to locations that provide greater connectivity, or in some cases direct funding towards underperforming areas. The concept of connectivity is well documented in social network literature and to some extent, transportation engineering literature. However, connectivity measures have limited capability to analyze multi-modal public transportation systems which are much more complex in nature than highway networks.