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44 I N N O VAT I O N S I N T R AV E L D E M A N D M O D E L I N G , V O L U M E 1 traffic forecasting capabilities at the workshop. These participants focused on locating new dwelling units in capabilities can be used to provide workshop partici- the northern portion of the county and new jobs in the pants with immediate feedback on the traffic impacts of southern portion of the county. After participants under- different plans and projects, as well as changes in specific stood the negative traffic impacts of these options, smart elements of a proposed development or land use plan. growth alternatives, with mixed-use developments and This approach allows participants to see the conse- balanced land uses, became the preferred alternative. quences of different alternatives. The use of the traffic forecasting model made the Traffic models used in workshops must be able to workshops more effective and enjoyable. It also strength- provide realistic results within approximately 15 min- ened SLOCOG's credentials in addressing land use utes. Participants will lose interest if the process takes issues. Feedback from participants, including the public longer and most workshop schedules could not accom- and policy makers, was very positive. modate more time. The 15-minute estimate includes all The Sacramento Area Council of Governments aspects of running the model, including data input, pro- (SACOG) included traffic forecasting in workshops cessing, and printing out or displaying the results. The examining roadway and transit projects for the 25-year model must be reliable and easy to use. The outputs Metropolitan Transportation Plan. A consensus had should focus on a few key performance measures. Thus, already been reached on future land uses through the simplified models are most appropriate for use in SACOG Blueprint Project. Workshop participants workshops. included the public, elected officials, and planning com- A traffic forecasting model was used to examine missioners. The goal of the traffic forecasting component the impacts of land use changes in visioning workshops of the workshops was to provide immediate feedback on sponsored by the San Luis Obispo Council of Govern- the effectiveness of different transportation elements. ments (SLOCOG) in California. San Luis Obispo, In the SACOG workshop, the inputs were road and located in the central coastal region, is a very environ- transit projects, which are more difficult to enter into the mentally sensitive area. The workshops were held as part model. The model results are also more subtle, making it of the 2050 visioning process. The main purpose of the difficult to identify appropriate indicators. Participants workshops was to build awareness and consensus, not were provided with a maximum funding level and a list policy analysis. The general public was invited to the of projects and roadway types. SACOG uses an older, workshops, and numerous elected officials and planning more complicated travel model. For use in the workshop, commission members also attended. The discussions the PLACE3s land use program was modified to display focused on alternative land use patterns to accommodate and manipulate the Cube/Voyager networks and to pre- 180,000 new residents in the county. pare the files for Cube/Voyager runs. Cube/Voyager was The goal of the traffic modeling portion of the run with the PLACE3s shell and the outputs were dis- workshops was to provide immediate feedback on the played using the GIS function. relationship between land use choices and traffic Use of the model added a great deal to the work- impacts. The traffic forecasting was conducted using a shops. Participants quickly learned that the available combination of geographic information system (GIS), budget did not result in significant improvements to the Excel, TransCAD, Word, and PowerPoint software pro- transportation system. The elected officials learned that grams. The output was presented in flow maps that the public participating in the workshop supported new showed traffic volumes and the volumecapacity ratio. toll projects and additional river crossings. The results were also presented in table format so partic- These two case studies highlight that traffic model- ipants could see the differences from the base condition. ing can be incorporated successfully into workshops. This The whole modeling process took approximately 15 approach requires a different type of model, however. minutes. Changes made to the model to accommodate Attempting to perform complex modeling quickly in front use in the workshops included using only daily forecasts of an audience is inherently risky. It is important to prac- and reducing the number of traffic assignment zones. tice before using a model in a workshop and to have back- Participants discussed the traffic forecasting results ups for hardware and software. Using travel forecasting for different land use scenarios. Many participants were models in the SLOCOG and SACOG workshops helped surprised to learn that land use location has a big impact reveal a disconnect between public preferences and proj- on traffic conditions. Previous discussions had focused ects that agencies felt the public wanted. It also provided primarily on how much development would occur and the public and policy makers with a more realistic picture how close it would be to specific individuals. The loca- of the importance of different land use options. tion of the development in the larger sense had not been addressed. The same number of jobs and households produced different traffic impacts depending on where Susan Handy, University of California, Davis, moder- they were located. Most of the scenarios proposed by ated this session.