changes in vanpooling schedules or transit fare subsidies, and any other type of
intervention that changes the total cost of transport of a consumer surplus theory, these benefits are calculated using benefits of Type A for existing users.
given mode. the rule of one
Following half of the
For the evaluation of user benefits spanning from changes in perceived costs, the Transfund model relies on projected mode share changes as estimated by regional four- stage travel demand models. In this context, it is necessary to input the current modal share, as well as the expected modal share to estimate the required generalized cost changes to achieve a given goal.
The report provides diversion rate tables that were then used as default values for predictive evaluation within a Microsoft Excel spreadsheet tool.4 The model evaluation results in a benefit to cost ratio that is then used as the “value for money” of TDM projects, which comprises:
transport users affected by the project and all externalities. constitute the numerator; and,
Net costs to the government of the TDM strategy being evaluated, which
constitutes the denominator.
Advantages and Constraints
One of the major advantages of this approach is that it seeks to establish a methodology to provide a comprehensive assessment of the full range of benefits and costs brought
by TDM initiatives while maintaining a framework
within the following
guidelines of the a perceived cost
approach, TDM strategies are fully accounted for
their impacts on internalizing costs that
would be otherwise left out of the decision making process same time, the approach retains the theoretical construct of cost analysis.
of TDM the more
At the benefit
Two major constraints were identified in the Transfund approach to evaluate TDM strategies. The first deals with the way benefits are measured, due to the notions of resource costs and cost corrections. The approach is based on perceived costs whereas it is assumed that individuals face the full cost of the alternative chosen. For example, parking costs are assumed to comprise not only the average cost of parking, but the full opportunity cost of using land for parking, the capital cost of the parking infrastructure, and the cost of added security (if any) to the parking facility. Summed all together, these components represent the full resource cost of parking. A resource cost correction is then accounted for, by assuming that the individual internalizes only a percentage of the total
4 The evaluation procedure was formalized into a Microsoft Excel spreadsheet model now being used by the Victoria Travel Smart Program. Essentially, it is the same spreadsheet, but with values tailored to the Australian network.