Estimate the Change of Mode Share by a Transit Project : A Case Study on the Houston METRORail Line

Public transit provides important services for urban commuters and transit dependent population. A key objective of most public transit projects is to increase regional transit ridership and mode share. Traditional survey has been widely used by a transit project to estimate the change of ridership. In a large metropolitan area with multiple public transit modes, it is costly and difficult to conduct survey on each transit and non-transit mode to evaluate impacts of a public transit project. A GIS-based simulation model offers a low cost way to estimate the mode share of different trips. This model utilized GIS Network Analyst functions to reconstruct travel costs for different modes impacted by facilities or services of a new transit project. A "Winner-takes-all" mechanism was applied to assign trips to optimal mode under different traffic conditions. Mode share was calculated based on the estimated trips in impacted areas.