The Evaluation of Route Guidance Systems

BACKGROUND

We were commissioned by the Transport and Road Research Laboratory to:

"collaborate with the German government and their representatives who are responsible for conducting the LISB trial in Berlin in order to produce an agreed methodology, which is acceptable in both Germany and the UK, for assessing the automatic route guidance systems which will be provided in Berlin and London." The brief suggested a number of aspects to be included, and required detailed proposals, timescales and costs for implementation in London.

1.1.2 The background to the brief lies in decisions to introduce pilot automatic route guidance systems in the two cities. The principles of the systems are similar, and have been described in detail elsewhere (Jeffery, 1987). In brief, they involve :

(i) a central computer which retains information on a specified road network, which is updated using real time information from the equipment users;

(ii) infra red beacons at selected junctions which transmit information to equipped vehicles and receive information from those vehicles;

(iii) in-vehicle equipment which includes a dead-reckoning system for position finding, a device for requesting guidance and specifying the destination, a micro-computer which selects the optimal route, and a display which indicates when a turn is required on the main network, and the compass direction and distance to the final destination;

iv) transmission from the equipped vehicles of origin, requested destination, links used since passing the last beacon and, for each link, the time of entry and departure and time spent delayed.

It is this travel time information which is used to update the central computer's knowledge of the best routes.

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