Decision Support for Improving Public Transport Network

When dealing with accessibility in a public transport network, isochronous maps are the common rule. Those maps are based on shortest distance algorithms run over simple or simplified networks. This contribution aims at representing the actual spatial distribution of the public transport offer in order to improve the usefulness to the urban community and to predict the evolution of the network according to the expected development of the agglomeration. The study combines the street (walking distance)and public transportation (buses) networks. The analyses rely on timetables and road maps completed by the public transportation company (TEC). Moreover, it makes use of built-up areas derived from satellite imagery. The processing requires raster- as well as vector-based procedures which have been achieved notably with the IDRISI software. Nevertheless the implementation of the decision rule relies on an original routine written by the authors. The area of interest concerns a part of the agglomeration of Lige (Belgium), including two secondary poles, highlighting their relation with the centre of the city and with each other. First the paper presents the typology of the public transport routes. Then the methodology elaborated for each transportation type is analysed, the shortest distance routes and their alternatives are extracted and combined within a raster process. The obtained results and their operationality are finally presented and the paper concludes with possible improvements of the methodology