Traffic light priority is a service that aims to guarantee green lights without waiting for public transport lines. The ultimate goal of the service is to increase the public transport commercial speed and reduce travel times for all users.

Torino was one of the first cities in Europe to experiment traffic light priority system with the ‘5T’ project in 1996 and then made it an integral part of its Mobility and Infomobility Centre.

The system is particularly complex and integrates two ‘worlds’: the one of traffic light control (which intervenes in real time on traffic light phases to fluidify traffic flows) and the other of public transport monitoring system.

To be concrete, let’s take line 4 as an example.

Line 4 is a particularly strategic tram line for Torino: it crosses the city from north to south for about 16 kilometers (and vice versa). On its roundtrip, the line crosses a total of 105 intersections. Of these, 85 provide the “green” to the tram (therefore a coverage of 81%).

If there were no priority, what would happen? In our measurement campaigns, we tested it: by temporarily “deactivating” the service, the tram took 70 minutes for the same route.

With traffic light priority, on the other hand, the tram takes about 60 minutes to travel 16 km from terminus to terminus. The user who habitually takes line 4 therefore enjoys a reduction in his travel times of about 10 minutes (more than 10%). If we multiply it by 255 working days, every year those who choose to use line 4 can save up to 42 hours of their time, with money savings too.

Not bad, right?

Currently the public transport lines operated by GTT and served by traffic light priority are nine: 3, 4, 9, 10, 15, 16​ (tramways) and 2, 8 and 68 (buses).

With the new Transport Plan of the City of Torino and GTT, we will be strongly committed to extending traffic light priority: the plan goal for 2027 is to have a total of 13 tram and bus lines with priority, effectively making public transport more and more competitive compared to the private car.