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Traffic Priority in City Traffic

European Union
Complete with results
Project Acronym
STRIA Roadmaps
Connected and automated transport (CAT)
Network and traffic management systems (NTM)
Infrastructure (INF)
Transport policies


Background & Policy context

The project was based on state-of-the-art low frequency tag/transponder, computer, radio communication and satellite technologies. 


It was the goal of the project for the innovative elements of the project to be found in the application area:

  • Use of low frequency tags/transponders for precise priority to certain vehicles, taking into account the actual position and speed of the vehicle so the the period of priority (green light) can be minimised and the amount of disturbance to traffic reduced.
  • Road infrastructure managers' user requirements with regard to traffic priority, positioning of vehicles, flexible traffic signalling and traffic management;
  • Ambulance service operators' user requirements with regard to needs for traffic priority and improved capture of data on ambulance operation;
  • Police requirements with regard to traffic priority, positioning and increased information to passengers

The project was planned to last 36 months with the work being broken down into the following three phases:

Phase 1: Definition

The task in the Definition Phase was to bring the users to develop the user requirement specifications for the TRAPRIO project (which, due to the diversity of traffic situations and diversity of existing systems in the participating cities/countries, will be a good basis for a system for the European market).

On the basis of the user requirement specifications, the necessary operational requirement specifications were established by the industrial partners in the project and a validation plan will be established.

Phase 2: Implementation

The project was implemented at at least two different sites with different traffic situations:

In Kolding a system of 3 ambulances, 1 fire-engine, 84 buses, 1 main station and approximately 25 road crossings/traffic signals) was established for optimal and differentiated control of the traffic signalling system to minimise the driving time for ambulances through the city and improve the bus transport system. A demonstration of different bus priority situations (e.g. different priority for different vehicles, different priority at different hours of the day/week, or deciding on priority depending on whether the bus is late or on schedule).

In Ashford (Kent county, ENGLAND) a system of 10 buses, 5 police cars, 1 main station and 8 road crossing/traffic signals was established to demonstrate the use of bus priority in an integrated "park and ride" system, and a comparison with a "park and ride" bus priority system based on Differential GPS in Maidstone was made possible.

In addition to full scale test activities, a study was carried out regarding the conflict between specific priorities for emergency vehicles and buses on the one hand, and the need to ensure the overall capacity of the traffic system on the other.

Phase 3: Full Exploitation

Two full scale demonstrations have been executed over a 12-month period in order to gain experience with the system under all weather conditions and obtain the necessary statistics.
Evaluation of the project included an analysis of costs and benefits based on the full scale demonstrators. Users were involved in the evaluation work and assisted in the specification of a future system for the European market.
Development of the solutions


Parent Programmes
Institution Type
Public institution
Institution Name
No fixed leading institution, but current chairmanship is held by the Danish Ministry of Science, Technology and Innovation (until June 2003)


Vehicle positioning

The TRAPRIO traffic priority system was based on TSS tags placed under the road surface, making it possible to position the vehicle with a very high accuracy (within 1 m). The TSS tags was used either as the only positioning system placed some hundred metres before each road crossing or in combination with another positioning system (e.g.

The TRAPRIO system brought higher accuracy than differential GPS and at lower cost. Compared to the solutions based on microwave and infrared beacons the TSS tag system had the advantage of being easier to place (under the road surface - no visible contact needed) and cheaper operation and maintenance as there was no need for energy supply/batteries.

Traffic priority

Several solutions have been tested for specific priority. In most cases the systems were based on either differential GPS or beacons (microwave/infrared). Some of the solutions were based on a direct communication between the vehicle and the signal box controlling a traffic signal/road crossing, whereas others like TRAPRIO were based on a communication between the vehicle and a control centre covering many traffic signals/road crossings (this only functions if cabling has been established between the control centre and each of the traffic signals/road crossings).

Ambulance priority solutions establishing a "green wave"for ambulances are also well known. The disadvantage of such solutions is that they are based on a fixed speed, resulting in problems if the ambulance is driving at a lower or higher speed.

In the TRAPRIO system, different priorities can be granted to different types of vehicle. The priority can be granted based on special conditions (e.g. buses if they are behind schedule but not if they are on time, or taxis granted access to special bus lanes provided there are no buses in the lane. Fully implemented, the TRAPRIO system gave road infrastructure managers, and politicians, the possibility of giving traffic priorities in accordance with the chosen policy and changing them again by making only simple software changes.


Compared to other similar solutions (for example microwave/infrared beacons), the TSS tag-based positioning/traffic priority system has the advantage of battery-free operation. Better traffic priority for heavy vehicles such as buses can lead to a more smooth operation, which in turn leads to savings in energy co

Technical Implications

Many cities in Europe and other parts of the world were considering some kind of traffic priority system in 2000. Compared to other traffic priority systems the TRAPRIO system had the advantage of being based on communication between vehicles and a control centre rather than direct communication between vehicles and each signal box. In this way specific traffic priority could be combined with other functions such as demand management and route guidance.

The TRAPRIO solution was of potential interest to:

  • 200,000 road crossings equipped with traffic signals in Europe (500,000 on world scale)
  • 60,000 ambulances, 500,000 buses and 50,000 police cars in Europe (190,000 ambulances, 1,500,000 buses and 150,000 police cars on world scale)
  • To this was a possibility to add trams, fire engines and maybe even taxis to this.


Lead Organisation
EU Contribution
Partner Organisations
EU Contribution


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