Forecasting Travel Demand

A travel demand or forecasting model is typically utilized by planners, engineers, MPOs and state departments of transportation to forecast future year transportation system deficiencies that may not exist today. These agencies also use models to evaluate the impact of alternative transportation solutions for development of long range transportation plans. They are primarily used to forecast traffic flows on the transportation system. Models are generally mathematical expressions that are used to replicate the movement of people and vehicles within a transportation system. The traffic forecasts are based on forecasted land use, demographic data, socio-economic factors and travel patterns unique to the region. Travel models are also created to support decision making by providing information about the impacts of alternative transportation and land use policies, as well as demographic and socio-economic trends.

In 2004 NWARPC developed the Northwest Arkansas Travel Demand Model for Benton and Washington Counties, AR. The base year for the model was 2005 and scenario runs have been developed for 2010, 2030 and 2035.

Between the years 2007-2010 NWARPC maintained the model in-house with continuous updates to the network, TAZs, socio-economic data, land use, etc. and used it for projects prioritization, scenarios and the 2035 Regional Transportation Plan and TIP.

In 2010, conducted a Western Beltway Corridor Study in Benton and Washington County that would connect to the future Hwy. 549 (Bella Vista bypass) in the northern part of Benton County. Part of the Study was to update the existing model to add McDonald County, Missouri to the study area. The model structure and code were also improved as part of the analysis.

In November 2012, NWARPC started a Transportation Alternatives Analysis Study that was funded by FTA and NWARPC matching funds as part of an Alternatives Analysis grant awarded that year. NWARPC analyzed the need for a major transit investment in the corridor, and to estimate costs, benefits and possible environmental impacts of the various alternatives. As part of the analysis, the consultants used the existing travel demand model to generate ridership estimates in the analyzed corridor.

In July of 2014, the upgrade of the existing travel forecasting model began which added mode choice to the model for the purpose of modeling vehicular travel as well as transit in the MPA. Under this scope of work NWARPC conducted a travel forecasting model upgrade that addressed all the model needs for a functional true mode choice model. The purpose of the project was to develop the mode choice model to include the transit component; upgrade the model from the 2005 base year to 2010 base year; add the Missouri portion of the MPA into the model; and develop the 2020, 2030 and 2040 forecast years. The model area includes Washington and Benton Counties in Arkansas and the McDonald County, Missouri portion of the MPA. This area encompasses 711 TAZs (Traffic Analysis Zones), which were also grouped into 11 TADs (Traffic Analysis Districts).

The 2040 forecast model has proved beneficial in identifying segments of the network that may need improvements in the next 25 years. A series of selection sets have been developed based on a 2040 Fiscally Constrained and Unconstrained List of projects and using forecasted socio-economic data from the model.

The Fiscally Constrained List for the road network consists of projects that can reasonably be expected to be funded with Federal-aid funds during the 25 year planning period. This is determined by estimates of Federal-aid funds that can reasonably be expected to come to the area given the area’s highway network, Urbanized Area, population, etc. These estimates are provided by AHTD and MoDOT and are not limits, nor are they guarantees of funding. They are conservative, reasonable estimates of future funding to guide development of the 2040 MTP. The Fiscally Unconstrained List includes projects not limited to the estimated available funding. An interactive map of the results of scenario runs for 2040 can be found at this at this link.

NWARPC has been collaborating with the two transit agencies (Ozark Regional Transit and Razorback Transit) in identifying further model enhancements, transit scenario testing, future scenario development and model sensitivity testing.