Conference of European Directors of Roads - TERN Location Referencing Trial

National Roads Administrations are required to supply information related to the Trans European Road Network (TERN) to the European Commission on a regular basis. To date no formalised method of consistently defining each national road network has been used which results in unstable network models that make it difficult to make comparisons between countries and to analyse trends in network condition over time.

In 2001 SG-Road Data developed a Location Referencing Method for the TERN to ensure a stable common network model that will permit direct peer comparison and enable comparison between different versions through time.

The TERN Location Referencing Method is based on a link and node definition of the network. The business rules for the positioning of nodes in still under consideration but it likely to rest at an exit-to-exit or junction-to-junction level – all Road Administration will generally hold data at this level of aggregation and this provides a largely stable reference network.

In 2002, SG-Road Data undertook a limited ‘proof of concept’ trial, based on a 1750km network of the TERN in Denmark, Germany, the Netherlands and the UK. The trial concluded that:

The TERN Location Referencing Method can be used by different countries to reference the TERN network and, if applied consistently, will enable comparisons between countries.
The method is robust, stable and can accommodate changes to the physical network such as new links and split links.
The method should include date attributes to enable changes to the network to be mapped.
Rules for the aggregation from national nodes at a greater level of detail than exit-to-exit will be a matter for national road administrations – the TERN Location Referencing method will effectively be a de-facto common European Standard.
Rules for the aggregation of data and the presentation of data at different scales will depend on the data types and what the user is trying to convey. It is therefore proposed that the definition of such rules is a matter for the user of the data and that the definition of Performance Indicators must include a definition of the rules for aggregation.
Although the focus of the trial has been the TERN, the location referencing method is applicable to other international, national and regional networks and therefore potentially supports the exchange of data between CEDR members about other roads.

The trial also identified a number of outstanding issues that needed further examination before the Location Referencing method could be implemented. SG-Road Data recommended at its Plenary Meeting in Budapest on 26 June 2003 that a pilot should be undertaken that would specifically address these issues and would consider a wider range of Member Countries, on a North-South corridor from Norway to Greece.

information from the Western European Road Directors, Directeurs des routes d'Europe de l'Ouest