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NYC 9/11 Public Portal Document

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housing market. The resulting model, the Chicago Area Transportation Land Use Analysis System (CATLAS) was used to study the response of the housing market in the Chicago area to specific proposed new subway lines. NYREG has a structure which, although similar to CATLAS, is more realistic and has been extended to include choices of shopping travel and housing type together with choices of residential location and travel mode. Although CATLAS was a multiyear dynamic simulation model, its capabilities were narrower in scope than NYREG (which is at present a static equilibrium model) because data limitations and technical constraints did not allow the treatment of non-work travel in CATLAS. Also, limited computing budgets in the mainframe computing environment of the early 1980's did not permit solving large versions of the model. The implemented version of CATLAS consisted of 1690 traffic zones, 2 workplace types (CBD and non-CBD) and 4 commuting modes. All housing was aggregated to a zonal total regardless of type. Supercomputers are now accessible to planning agencies and academic researchers and the speed of desk-top computing capability is quickly approaching or exceeding that of traditional mainframes. Hence, models which are larger and more complex than CATLAS can be solved very rapidly and at much less cost than was possible a decade ago. In addressing many of the deficiencies of CATLAS, NYREG has also been implemented on both a CRAY supercomputer and a SUN workstation.

What Questions Does NYRE6 Address ? It is useful to give a couple of narrative examples which illustrate the way in which the regional equilibrium model can be used to analyze a change, policy or scenario. The reader is encouraged to come up with examples of his or her own making by keeping in mind the list of model inputs and outputs presented below.

Example One: A Station Closing As one example, suppose there is a station closing in midtown Manhattan. This will affect the travel times on certain subway routes. Using detailed information about the transit network, the user of the model would compute (by means of TRANSCAD software or other comparable procedures) how the travel time by subway from each zone to each other zone would be changed. In the case of the station closing, it will be found that certain zone pairs will experience a reduction in travel time because trains will stop in one less station on thieir way to and from these zones. However, zones near the closed station may experience increased travel times, because travelers originating from those zones will have to

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