What is Computer Modeling?

In order to plan for future transportation needs, such as those included in a Regional Transportation Improvement Program, transportation planners must have some means of predicting those needs.

The method used by regional transportation planning agencies statewide is a special computer program that assimilates a wide variety of data and then forecasts future demand.

Data used in this process includes employment rate, occupational catagories and the number of single-family homes and multi-family residences. Additionally, population growth, employment tools, planned transportation improvements, external incoming traffic counts (gateways) and current traffic counts in certain areas (screenlines) are overlaid onto a grid of the existing transportation system and proposed future system.

Staff can then forecast a variety of data such as trip generation information and peak-hour traffic volumes. The resulting data enable staff to simulate future traffic demand so that transportation projects can be compared and funds used where they are most needed.

The model is also important in determining conformity to air quality requirements. Staff can compare emissions with a proposed project in place versus emissions without that project to determine the project's impact on air quality. If a road is widened, for instance, that road may attract a higher traffic volume and greater speeds, which would affect emissions. However, if the roadway had been congested and now traffic is flowing smoothly, emissions would be reduced.

The computer model is also used in developing traffic impact studies for site plans and zoning changes.