South Carolina continues to attract new residents (>1% per year), tourists (30+ million visitors per year), and businesses (BMW, Boeing and major tire manufacturing plants). This growth indicates a greater demand for mobility which has a tremendous impact on maintaining the state’s highways. Given constrained roadway funds, the Multimodal Transportation Plan (MTP), “Charting a Course to 2040” uses an economic project prioritization approach to identify which improvements generate the greatest economic impacts (jobs, income, and output). Using this approach, a statewide travel demand model (TDM) was developed to provide information on the highway systems performance to evaluate the state’s economic competitiveness and quality of life per MAP-21 requirements.
The South Carolina Statewide Model (SC SWM) was developed by stitching together various Metropolitan Planning Organization (MPO) and Council of Government (COG) TDM data. There are 11 MPOs and 10 COGs in SC, all of which have TDM data. A detailed review of the model data (land use, highway networks, external data, truck data, model years, trip purposes, trip rates and parameters) was conducted to deem the appropriateness of the models for use in the SC SWM. Further, the geographic extent of the TDMs was analyzed as several of the models overlap. This analysis resulted in eleven different MPO/COG models appropriate for stitching together to form the SC SWM. This paper will report several lessons learned in this process including the order to merge together network and zonal data, methods to conform inputs for a common forecast year, and linkage to the MPO/COG model forecasts and other datasets.
Another component of stitching together the TDMs was to ensure functionality for output of performance measures required for economic project prioritization including travel patterns (time and miles traveled, delay, capacity needs, etc.) and travel-efficiency benefits associated with each grouped corridor-level infrastructure improvement. This paper will discuss these measures and benefits which can be monetized and input into economic models to ascertain the economic impacts and rank corridor improvements for funding purposes.