NYC-WTC_000187725

NYC 9/11 Public Portal Document

31 the value of the portion of the total discretionary time which can be allocated between commuting, shopping travel, and leisure. B (>1) is the assumed ratio of annual generalized income to annual monetary income. is the annual housing rent (or rent­ equivalent owner-occupancy cost) per dwelling unit of type k in zone j . Ais two times the given number of work days per year, is the generalized cost of commuting (money travel cost plus the value of time spent on commuting) per one-way trip, and g^jin generalized income expended per shopping trip. These two generalized cost functions are given by: (3)

and,

(4)

SFiji„=2Cj2A

In these equations, c^j^ is the money cost of a single commute from workplace i to residence zone j via mode m, and T^j^ (or tj^^) is the one-way time it takes in minutes to make such a commute ^(or shopping trip) with A, the ratio of the value of time per minute in commuting to the wage rate per minute. To obtain the constant 240, multiply 8 (the assumed number of working hours per day) by 60 minutes per hour and then divide this product by 2. 240A is the total number of minutes spent working annually and y^/240A is "income per minute of work".

The shopping trip expenditure function, g^jxn' i® defined to include not only the generalized travel cost of a shopping trip but also the money spent to buy goods and services on that trip. The constant z stands for the shopping purchases per trip, reflecting our assumption that the quantity purchased per trip and the unit price of the composite good are constant.^ Cjj^p is the monetary cost of a shopping trip and t^j^n travel time. As is well known, the utility function (1) with the restriction on its coefficients (!•) results in demand functions for shopping trips such that each household expends a share

This assumption can be relaxed by allowing z to vary by 1. In the present study we do not have data on shopping expenditures that would allow us to calibrate the value of Zj for each 1.

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NYC-WTC_000187762