Response to Policy

     Policy 1     

     To demonstrate that the existing system is incapable of accommodating the projected, design-year traffic, the user should develop a carefully designed set of alternatives within Tranplan that do not rely on the construction of an interchange. To assist in the file management portion of the analysis, it is recommended that each new alternative be located in a separate directory appropriately named to provide full understanding of the alignment. Then, for each of the alignments developed, the user should perform a complete run of the model through Tranplan to calculate the roadway volumes that result from the alignment alternative.

     After running the network through Tranplan and returning the information to GIS, there as several analysis that should be examined before entering any information into the HCS. The main items to examine are 24 hour roadway volumes and either 24 hour or peak period volume to capacity ratios. An important consideration within this process is the potential modification of the network or factoring of the roadway volumes to represent peak period travel in the network, as this is the travel of most importance to the HCS.

     Moving from the GIS-Tranplan analysis, the volumes and turning movement counts can be displayed and stored to be entered into the HCS. Then the user can run the HCS modules of ramps, freeway operation and intersection analysis, which ever are appropriate.

     Policy 2

     To show that all reasonable alternatives have been addressed, looking at the list of alternatives, there are several options that warrant examination by someone outside the planning agency. These include the transportation system management schemes such as ramp metering, mass transit and HOV facilities.

     The examination of all possible design alternatives should be performed through the development of different scenarios with the GIS-Tranplan modeling environment. To facilitate this process, developing each new scenario in a separate directory will be most beneficial. Then all of the new scenarios need to be modeled with Tranplan and evaluated with the HCS as required by other policy statements.

     Policy 3

     Demonstrating that the proposed access does not have a significantly adverse impact on the safety and operation of the interstate facility and surrounding streets. This analysis will be performed using a combination of Tranplan-GIS and HCS programs. The analysis that needs to be performed is similar to items mentioned to response to Policy 1.

     Policy 4

     Demonstrating that the proposed interchange will provide access for all turning movements is a process that will be shown by the developers/designers of the interchange. There is not specific modeling and analysis necessary for this policy beyond examining the proposed design.

     Policy 5

     To show that the proposed interchange is consistent with local and regional plans, the existing land-use and changes in land-use should be shown, both with and without the GIS. Without GIS, the identification of the number of jobs or residents that will move to the area as a result of the interchange. Within the GIS, the production and attraction parameters within the Tranplan network can be displayed to demonstrate appropriate increases or decreases that would be expected as a result of the interchange.

     Policy 6

     For instances where multiple interchanges are planned, all possible changes must be examined together to determine the operating characteristics for the system.

     Policy 7

     The area must demonstrate that the interchange improvements were developed as part of a comprehensive plan and the effects have been examined with respect to the entire metropolitan area.

     Policy 8

     The location must contain appropriate documentation demonstrating that the interchange location meets all planning and environment constrants and considerations.

     Select any of the options to receive more information or click on the back button to return to the main interchange justification page or the site map button to go to the site map.