Transportation and economic development evaluation model

The system dynamics methodology is used to develop a computer simulation model to determine whether to add lanes to a congested highway or build a new, more direct, facility. Fundamental to this evaluation is the incorporation of non-user measures of effectiveness to go with the traditional highway user measures of effectiveness, such as the Benefit-Cost Ratio. In the system dynamics methodology three alternative forms of the model of a system are used: verbal, visual, and mathematical. The verbal description is diagrammatic and shows cause-and-effect relationships between many variables in a simple, concise manner. The visual model or "causal diagram" is translated into a mathematical model and system equations.

The model is comprised of four sectors:

1. population sector
2. economic sector
3. university sector
4. transportation sector

The model applies to the area of Blacksburg, Christiansburg and Roanoke (city and county). with special treatment to Virginia Tech through the university model. The simulation results of the non-user benefits along with user benefits is used to evaluate the alternatives in the Blacksburg-Christiansburg-Roanoke corridor.