Exchanging data and information on the data (metadata) between transport models, as well as between transport models and other software, e.g. GIS, is a difficult task. There is often the problem of loss of information because the exchanged data does not contain the information required. And there is also often the problem of inhomogeneous and proprietary data formats forcing the users of the data to re-format and re-combine the data from scratch every time. The solution to these problems is that not only data needs to be transferred, but also the precise meaning of the data (metadata), including the underlying conceptual model. The `Generalised Transportation-data Format' GTF, based on the original work in Mandel & Ruffert E. (1999 & 2000) was developed to meet these demands. GTF is a proposed conceptual model (covering the most widely used objects in transport modelling), an exchange format (GTF-XML) based on standard XML, and an interchange language to run transport models and retrieve results. This allows software applications, `GTF Translators', to exchange information and data between transport models and other software. The work started in an EU-research project BRIDGES where a survey of different conceptual models and formats was carried out (Nielsen et al, 1998). This led to the first version of GTF (Mandel & Ruffert, 1999). The work is continued and refined in the thematic network SPOTLIGHTS under the EU's 5th framework programme, where further surveys, reviews and user input are carried out. As SPOTLIGHTS is funded by the EU, it is the ambition that GTF eventually will become an EU-standard for the exchange of transport modelling data. This will provide a strong platform for utilising earlier work and transport models when building new transport models, as well as a tool for comparing transport models that cover the same geographic area. Both aims will be very useful for research as well as practice in the field of transport modelling. After an introduction in section 2 to the current situation and problems, the paper suggests an information structure (section 3), entities (section 4) and an exchange format (section 5). The present paper describes GTF in general, while a description of the exchange format and TIP (a protocol to run transport models remotely i.e. through the Internet and retrieve results) would be too voluminous. To set the work into perspective, comparison with the GIS-based Transport Object Platform (TOP) for public transport is carried out. Finally the conceptual model is summarised and the perspective - and organisational hurdles - for the future use of GTF are outlined in section 7. The paper includes a list of projects and acronyms following the references.
Abstract