The impact of metro lines on public transit accessibility and land value capture in Nanjing

This paper takes Nanjing metro Line 1 and Line 2 as an example to construct the urban public transit network, which is used to measure the changes in transit accessibility with multiple indicators. Based on the distinctions between before and after building metro line, this paper provides diverse value added response modes with different land prices capture on the transit accessibility-added of metro, which offers a scientific basis for law inquiry and policy formulation. The results show that the metro enhances the urban public transit accessibility in time costs, sphere of influence, and network morphology and so on. Absolute accessibility increase in the peripheral region is larger than that in the central area, while relative accessibility increase in the center is larger because of "radius trap", which brings about "center expansion & peripheral collapse" pattern change. The change of land price pattern is similar with that of accessibility pattern. Thus, space differentiated external economy comes into being with the effects of metro. Different types of land use have different land value capture modes, for example, commercial land value increase shows a logarithmic response mode, residential land value increase shows an index response mode, while industrial land value increase shows a linear response mode. It is indicated that metro contributes 1/3 to urban land added value, in which the external effect on commercial land is higher than that of residential and industrial land, with a ratio of 2:1:0.3. The result may be beneficial to assess the Nanjing Metro influences on the overall urban land use, and provide the evidence for levying urban land and housing differentiated taxes to compensate the metro economic externality losses.