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Case Study:
Sacramento, California
Application
Scenarios: Travel Demand Model Results
This section highlights a few of the findings on individual and combined effects of transit, land use, and pricing scenarios using SACMET96. Scenarios were evaluated with respect to vehicle-trips, vehicle-miles of travel (VMT), vehicle-hours of delay (VHD), mode shares, and VOC and NOx emissions. A much more detailed discussion and interpretation of results is provided in Johnston, Roder, Choy, and Abraham (2000). All comparisons are to the baseline scenario unless noted.
Transit scenarios - In 2005, the effects of the transit-only scenarios are small (roughly a one percent reduction in trips and VMT). The pricing and transit/pricing strategies have larger effects, reducing VMT by four to five percent and VHD by 20 to 25 percent. In 2015, the addition of TOD to the transit scenarios greatly increases their effectiveness at reducing VMT, providing a six percent reduction without pricing and a nine percent reduction with pricing, compared to the baseline scenario (Figure 5). Highway scenarios - The HOV scenarios exhibit results similar to the HOT scenarios. Both scenarios alone lead to slight increases in trips and VMT and small reductions in vehicle delay. When combined with road-oriented development patterns, VMT is reduced by about two percent and delay is reduced by 11 to 16 percent. When additionally combined with pricing, VMT is reduced by four to five percent and delay is reduced by over 20 percent. None of the HOV or HOT scenarios led to a significant reduction in vehicle-trips (Figure 13). Emissions - As would be expected, emissions impacts closely followed VMT impacts, although impacts varied somewhat depending on whether vehicle-trips were reduced as well. The authors found that land use intensification policies may be more effective in reducing both VMT and emissions when combined with transit than with HOV- or HOT-lane policies. User benefits - In the 2005 scenarios, the pricing and transit/pricing scenarios produce the highest economic benefits, eight to nine cents per trip, compared to benefits of one to two cents per trip for the scenarios without pricing. In the 2015 scenarios, the addition of TOD to the transit scenarios significantly increase the economic benefits compared to 2005, with benefits of 10 to 15 cents per trip. In this case, significant user benefits are achieved even without pricing policies. For the road-oriented scenarios, the HOT scenarios provided greater user benefits than the corresponding HOV scenarios.
Interpretation of User Benefits
In this method of assessing user benefits, a benefit of 10 cents per trip can be interpreted to mean that the average traveler would be willing to pay an additional 10 cents per trip to have the scenario travel conditions rather than the Base Case travel conditions. |
Equity - User benefits were calculated separately for the three income groups in the model (Figure 7). The results show that light rail alone has a relatively small impact on each income group. Pricing has a positive impact on the middle- and upper-income groups, but a negative impact on the lowest-income group. The transit/TOD scenarios provide positive benefits to all income groups. The addition of transit/TOD to pricing eliminates the regressive effect of pricing by itself, but still provides the greatest benefits to the highest-income group.
Figure 4.
Transit and Land Use Scenarios: SACMET96 Model
Travel, Percent Change from Base Case (2005)
Source: Johnston, Rodier, Choy and Abramham (2000).
Figure 5.
Transit and Land Use Scenarios: SACMET96 Model
Travel, Percent Change from Base Case (2015)
Source: Johnston, Rodier, Choy and Abramham (2000).
Figure 6.
Transit and Land Use Scenarios: SACMET96 Model
NOx Emissions, Percent Change from Base Case
Source: Johnston, Rodier, Choy and Abramham (2000).
Figure 7.
Transit and Land Use Scenarios: SACMET96 Model
Economic Benefits Per Trip vs. Base Case (2015)
Source: Johnston, Rodier, Choy and Abramham (2000).
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