Traditionally, transportation demand management (TDM) programs have been initiated in large urban areas with high population density, centralized employment centers, and numerous transportation alternatives. This paper analyzes what the likely effect would be of implementing similar TDM programs in a smaller urban area, namely the Des Moines, Iowa metropolitan area. The analysis was divided into three feasibility tests: Will a TDM program solve projected traffic congestion problems ? Are there adequate travel time savings to overcome start-up and monitoring costs ? and will the costs borne by the private sector create economic hardships in excess of the benefits ? The major TDM programs studied included TDM programs studied included altering the price and supply of parking, offering transit improvements and incentives, and implementing high occupant vehicle incentives. The results indicate that the large incentives to drive alone, such as ample parking supply, insufficient transit coverage, along with density and location problems, limits the ability of TDM to solve the growing traffic problem in the Des Moines area. However, the results do indicate that a voluntary TDM program would have benefits to the area in terms of travel efficiency that outweighs the initial and continuing administrative and economic costs of the program. Therefore, it was recommended to include a TDM program with other options, such as a limited capacity expansion or a ramp metering program, which would, in fact, solve the projected traffic problem. (A)
Abstract