Linking Travel Demand Modeling with Micro-Simulation

Abstract

Travel demand forecasting and traffic simulation are two important components of transportation studies. Travel demand forecasting models have typically been used for planning purposes for future transportation systems at a macroscopic level. Traffic simulation tools are often used to account for the movements of individual vehicles at a microscopic level. Traditionally, there has been a disconnection between the macroscopic and microscopic levels. The desire to link travel demand models and traffic simulation models has been recognized by transportation agencies and professionals.With the advent of computing technologies, transportation agencies are increasingly adopting microscopic traffic simulation models for large-scale design projects to obtain more detailed operational analyses. One critical issue that transportation agencies often encounter is that constructing a microscopic simulation model from scratch still consumes a significant amount of resources. This research aims to develop a conversion method to extract a portion of a travel demand network in TransCAD for constructing a consistent subarea of interest, and then convert it into a microscopic simulation in Synchro/SimTraffic.TransCAD in nature is a macroscopic travel demand modeling tool. Synchro/SimTraffic provides detailed microscopic traffic analysis. Dynamic Traffic Assignment models serve as a mesoscopic tool for traffic analysis, which lie between TransCAD and Synchro. To convert a TransCAD model into Synchro for micro-simulation, a cross-resolution simulation method using NeXTA/DTALite as an intermediate tool was adopted. This method develops a DTA model that ensures consistency between TransCAD traffic demand and Synchro vehicle flow, and allows users to easily define a subarea in the DTA model and convert it to Synchro. The conversion method was tested for its functionality using the TransCAD model maintained by the Regional Transportation Commission of Southern Nevada (RTCSN). The test application demonstrated the integration of TransCAD, DTA, and Synchro as well as the successful application of converting a TransCAD network to DTA, and a subarea from DTA to Synchro. Results from the case study show significant time savings by using the proposed method compared to traditional manual methods. Major conclusions and some outstanding issues from the research are documented in this thesis. A User’s Manual for the conversion process is also included in the thesis.