The aim of the project is to study, develop and test a traffic signal control system which is not based on a precalculated cycle masterplan as are most current systems, but on a real time system using dynamic programming which continuously adjusts green times in order to maximise the road network's throughput or other performance criteria.
Nowadays most current traffic light control systems are based on a precalculated cycle masterplan. They are not adaptive and therefore are unable to react to a variation of demand in traffic flow. Installed on an intersection to regulate the traffic, those systems are not optimal.
The aim of the project has been to study, develop and test a real time urban traffic control system. The main feature of this system has to be its capacity to always optimise traffic regulation by using the PRODYN algorithm.
The system will allow for several regulation levels. So it will permit optimisation of the traffic crossing an isolated intersection, optimisation of traffic for a set of intersections without a traffic control centre and optimisation of traffic for a set of intersections working under a traffic control centre.
To achieve the objectives of the project it is important to take into account field safety and traffic management constraints, analyse thoroughly current traffic controllers to discover their capabilities and limitations, carry out theoretical studies about alternative architectures and field problems, make PRODYN capable of operating all European types of traffic controller safely and efficiently and assess the operation of the system in real world tests.
A prototype was made available on 01/09/92
The research into real time urban traffic control has included:
new development in the PRODYN road traffic control algorithm;
the development of a prototype interface, carefully designed to allow connection with every European traffic light controller;
recommendations for the integration of PRODYN into a road transport informatics (RTI) environment;
field experiments performed in Toulouse.
The results on one intersection and on an 8 intersections network show respectively 9% and 8% reduction in travel time.
In addition the research resulted in:
an improvement of the PRODYN algorithm;
the introduction of a controller stage which enables the algorithm to adapt to different pedestrian signal control philosophies;
a prototype system built around the improved algorithm.
Based on PRODYN algorithm, the system will allow for several regulation levels given a high degree of control to traffic authorities. These will include:
- control of an intersection independently of all other intersections
- control of several intersections as a group under the direction of a central unit
- control of a set of interconnected intersections under the direction of a single unit.
The system will be tested in the ZELT laboratory.
Program specifications for one intersection, ten intersection and for the central unit equipment.