Simplified Model of Local Transit Services

The California Statewide Travel Demand Modeling (CSTDM) Framework is a comprehensive model system designed and developed for use in transportation policy analysis and forecasting. It includes representation of all major components of both long and short distance transportation covering the entire state. A novel hybrid system is used to represent the full range of rail and bus transit services that are available. Rail and fixed busway services – including all long-distance rail, commuter rail, light rail transit (LRT) and busway services – are represented in the standard manner, using explicit node and link networks, and the relevant in-vehicle and out-of-vehicle service characteristics for journeys are determined as standard skims of these networks. On-street bus services are not represented using explicit networks; rather, the relevant in-vehicle and out-of-vehicle service characteristics for journeys are determined using functions of other transportation network variables, land use descriptors and relevant policy indicators. These functions are simplified econometric models that have been estimated using observations of transit service obtained from Transit Data Feeds available on the Google platform. The network and simplified components are integrated in order to allow transit paths with both rail and on-street bus components to be considered by the various travel choice models included in the Framework. This hybrid system provides a suitable representation of transit for an area of such size, facilitating consideration of transit service policies, while also obviating the need for extensive transit coding, which would be a daunting task for such an area. As such, it is a very practical modeling approach.