this example transit travel time. In the figure, D0,j0
represents the demand for car trips at
the initial value of transit travel time and car parking cost, while D1,j1
represent the final
demand for vehicle trips at the new parking cost and transit travel time. Let Q symbolize the number of vehicle trips and P the cost or price per vehicle trip. Note that the cost per vehicle trip could comprise several components including parking, operating and maintenance costs.
The two policies exert two effects on the demand for SOV trips. The first is determined by the reduction in transit travel time. Assuming that SOV and transit are substitutes (individuals consider them as two competing travel modes), a decrease in transit travel time causes a modal change from SOV to transit. This is represented by the move from point A to point B and depicted by a shift to the left of the demand for SOV trips, a reduction in 44 vehicle trips. The second effect is determined by the parking charge increase and is represented by the movement along the new demand curve from point B to point C; a reduction of 94 vehicle trips. The latter impact is greater, indicating the relevance of parking pricing policies on the demand for SOV trips. 20
2,956 3,000 Figure 3 Demand for SOV trips
The reader might wonder what the effect of a SOV parking charge increase would be on the demand for transit trips. This requires adjusting Equation (5) to include a parameter
As confirmed by empirical analyses on direct and cross parking price elasticities.