Digital tools for urban development project: GIS application to PTAL assess and land valuation and traffic simulation for piazza renewal

Abstract

Nowadays, the increasing density and expansion of urban areas make cities as complexes with massive activities. The new input of the upgrating urban functions brings uncertainty to the transformation of downtown. Previous to the urban design, to visualize and assess the land value, and evaluate the possible density of the urban development supported by the public transport, a GIS platform is required. During the project of urban renewal design for the 13 km2 area of downtown Baotou (China), our GIS work as advanced territorial analysis tools, helps to provide the technological support for the decision of the urban spatial plan. The overall project site has been divided into a 20x20m grid, and in each cell a specific value for each factor deems relevant for this design stage was assigned. The factors include topographical morphology (sun exposure, elevation, slope or flat terrain), the positive ones are the accessibility, proximity to public transport stops, to waterfront or park, to attractive places (cultural and commercial facilities), and so on. While the traffic congestion, pollution and noise are considered as Negative factors. For some important urban facilities like shopping mall, theater or symbolic buildings the calculation of “visibility” is also a crucial factor. This process allows us to derive new information from the existing data and to analyze complex spatial relationships. The public transport service provides great support for the future construction. Based on the capacity of public transport modals and the estimated frequency, the PTAL (Public Transport Accessibility Level) map, produced by GIS as well, reflects the acceptable passengers and hence shows the support to the density of the future development, the PTAL level is direct related to modal share and quantify the usage of private car. In this sense the 3D PTAL map can be regarded as the visualization of the city’s skyline. Vice versa, if the density estimated by PTAL could not meet the requirement of official plan the increase of certain capacity and frequency of public transport vehicles can be accordingly suggested. In a word, the maps of land value and development density could help the urban plan to utilize the land portion or find suitable locations for main urban attractors in a more reasonable way. In addition, in some cases the renewal design of some important urban areas requires the modification of traffic flows. Does the new project meet the necessary of urban livability in term of traffic generation? Or would it improve the organization of traffic flows? The traffic simulation could assess and visualize the effect. Our project for Piazza Santa Croce (Parma) demonstrates this solution.