Case Study:

Sacramento, California

Conclusions

Advantage of Land Use Model

The use of MEPLAN, or another transportation-land use model such as TRANUS or UrbanSim, provides a number of advantages for assessing regional transportation and land use policies. For example:

• The inclusion of land use effects generally led to higher travel impacts (positive or negative) for comparable policy scenarios. The extent to which differences in models and scenarios contributed to this effect is unknown. It is possible, however, that much of this effect is due to the reallocation of population and employment in response to changes in travel times and costs. For example, in MEPLAN, HOV improvements led to increases in VMT that were disproportionate to trip and mode share impacts, suggesting a lengthening in average trip length.

• Interest is growing in transit-oriented development, and a number of regions have modeled the travel impacts of concentrating development in transit station areas. The actual mechanisms for influencing development, however, are generally not identified. A land use model such as MEPLAN, which simulates land markets, can be used to test different policy mechanisms for achieving development objectives. In this application of MEPLAN, it appeared that it would be difficult in practice to achieve the desired level of reallocation. For example, no combination of "reasonable" tax incentives and subsidies in MEPLAN was sufficient to obtain densities in transit zones as high as those manually allocated to transit zones in the SACMET96 model.

• The results are not always intuitive and are by no means linear combinations of individual policies. For example, in this study, parking pricing tended to discourage development from TOD zones, thus offsetting tax incentives.

• Models such as MEPLAN, TRANUS, and UrbanSim have a strong economic foundation, and business and residential location decisions are modeled based on a range of factors. Land markets are key to the modeling framework, with prices driving development. This is in contrast to models such as DRAM-EMPAL that reallocate land use only on the basis of transportation accessibility. UrbanSim advances the state-of-the-practice by using the logit model structure, typically used to predict transportation mode choice, to model a broad range of decisions such as business and residential location.

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