Using GIS modelling to assess accessibility improvements and its potential indirect effects on the environment due to transport infrastructure plans development

Abstract

The Strategic Environmental Assessment Directive (2001/42/EU) establishes that the Environmental Report must include the identification and evaluation of the likely significant effects on the environment of implementing the Plan or Programme due to be studied. Transport Plans usually generate accessibility improvements or facilitate access between two given points on the territory. One indirect impact that this action implies is a likely pressure increase in those areas where a great improvement in their accessibility is gained, mainly through high speed motorways. This new pressure comes from the sudden and sometimes messy attraction of potential activities that could vary from industrial, agriculture or services sectors, an increase of tourism or recreational activities..., and the appearance or intensification of residential demand, including secondary or recreational houses.
The Transport Research Centre of the polytechnic University ofMadrid (TRANSyT) has coordinated a research project, financed by the Ministry of Public Works, which its main objective has led to obtain, develop and analyse interdisciplinary information to assist on a better infrastructure planning process. In the framework of this project, a methodology has been proposed to assess potential indirect impacts on the environment caused by transport infrastructure developing in previously semi-isolated areas. The process involves the computation of accessibility indices based on travel time estimations on road and railway networks in conjunction with its combination with Natural Quality cartography, also developed through an ad-hoc methodology.
Two analyses have been performed using Iberian transport networks, both for 1992 and 2004, which were later crossed with the Natural Quality cartography obtained in a previous stage of the project. In the light of these analyses, the performance capacity of the Geographic Information Systems is proven and highlighted, concluding that this methodology is suitable for planning improvement.