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O V E RV I E W O F T H E P O L I C Y I S S U E S 5 Congress, Consultants, U.S. DOT, Researchers State DOT Technical Policy Guidance Guidance and Funding Application MPO Citizens, Guidelines Agencies Feedback Recommendations Partnerships: TRANSIMS Local and State MPOs/Private Decision Makers Single State-MPOs Peer Review TMIP Listserv Implementation FIGURE 4 Role of MPOs in the transportation decision-making process. used by the 26 MPOs in the state. There continues to be When most of us went to school, we were trained to growing interest in rail freight operation simulation and help predict and analyze future assumptions. We were inputoutput and commodity flow models. National and trained to inform the public of the consequences of spe- statewide data sets need to be consistent with regional cific futures based on one set of demographics. We were data sets. Regional data sets often suffer from the lack of trained to test alternative road and transit networks. We consistency within the model itself or within the activity also learned to examine one road and transit network decision-making tree. and test alternative demographics. Finally, we learned As modelers, we face two important issues. The first to examine alternative networks and alternative issue is that we do not tend to talk about context. We demographics. need to establish the context within which the models However, we live in a different world today. Elected are being applied. For example, regions are growing at officials are not modelers. Some policy makers in our different rates. The size of regions varies. Congestion lev- region have suggested that we run our travel models els are different and the air quality status may be differ- backwards. This approach involves the transportation ent. Model applications may be used for new start profession identifying the transportation networks, the projects, megaprojects, toll roads, and value-pricing transportation modes that should be built in various cor- projects. ridors, and what projects should and should not be It is not fair to us as modelers to recommend model added to corridors so the region can sustain the demo- elements to a community if we do not first establish a graphic forecasts. context for the community. We also need to remember The DallasFort Worth Metroplex is growing by who the client is in the development and use of technical about 1 million people every 7 years. Current trans- tools. If we as professionals do not do a good job of portation funding cannot keep pace with the needs of answering the questions, the political process will answer this increased population. Policy makers are looking at a them for us. variety of transportation options, including tolling, vari- able pricing, managed lanes, and commuter rail to Information System accommodate the mobility needs of a region with a cur- rent population of 6.5 million that is continuing to grow at a rapid rate. Input-Output Model The land use model starts with the residential location Land Use Model Travel Model of the housing trip, rather than the trip distribution model, which picks the work place location of a specific Evaluation/Recommendations trip. The model efforts under way in Denver, Colorado, focus on simultaneously calibrating the land use and the transportation elements. The model that is run back- Implementation wards is the land use model. Using a land use model FIGURE 5 Role of modeling in the implementation process. starts with a need to know what the public really wants.