Estimating Reduction Coefficients of Parking Allocation Based on Public Transportation Accessibility: A Case Study on Nanjing’s Central District

Rational parking allocation criteria are critical in addressing urban parking challenges and promoting the sustainable development of urban transportation. It has been common practice to reduce parking allocation for buildings according to the extent of the public transportation accessibility; however, the calculation of reduction coefficients lacks scientific rigor. This research proposes an estimation approach for reduction coefficients of parking allocation according to public transportation accessibility. First, public transportation accessibility is analyzed using Javier Gutiérrez’s weighted-average travel time model, optimizing the existing parking zoning scheme. Second, a multinomial logit model is built based on residents’ trip survey data to assess the cross-elasticity of the public transportation accessibility (travel time) with the probability of car travel. Third, the reduction in the private-car-travel probability is approximated as a parking reduction, and the reduction in the public transportation accessibility is translated to a reduction in the parking allotment, using cross-elasticity as a bridge. Finally, an empirical study is conducted on Nanjing’s central urban area, analyzing the reduction ratios within different parking zones around metro stations within specific distances and the interaction effects of these two scenarios to verify the rationality of the calculated reduction coefficients. According to the study, parking allocation standards in Zones I and II can be reduced by 10.6% and 7.5%, respectively, based on Zone III standards, while parking allocation standards within 100 m, 300 m, and 500 m of metro stations can be reduced by 17%, 12%, and 8%, respectively, based on the original standards. This paper can serve as a reference for the development of parking standard policies for public buildings.