Traffic lights

Roma Servizi per la Mobilità is responsible for running and maintaining of the entire network of  traffic lights and electric signs in Rome: traffic lights, electric traffic signals and electronically-regulated crosswalks. 

The activities include designing new traffic lights, maintenance of the existing ones, searching for new technologies and systems analysis for traffic regulation, both vehicular and pedestrian.

All the newly built traffic light systems are equipped with LED lighting.

There are 1387 traffic lights in Rome: 528 are centralised (UTC) and 859 are not. More specifically, the centralised ones are divided in:

  • 269 Omnia-Utopia (Swarco-Mizar)
  • 131 TMacs (La Semaforica)
  • 92 Sigma-Sigma Plus (Selex)
  • 36 Road Manager (Project Automation).

Most of them are on the major road network for private traffic, mainly on roads that lead to the centre of Rome (Colombo, Laurentina, Appia, Tuscolana, Casilina, Prenestina etc.)

As part of the European Project ICT-Emissions, a series of road surveys have been carried out; those carried out on traffic lights coordination on a traffic route of Rome have provided important results: +8,5% journey speed, -7,7% of the total number of stops of vehicles, -9,8% on average stops for each vehicle and -11,8% on average time wasted by each vehicle, that means -4,8% of CO2 emissions (in g/km).

Traffic lights are divided, according to their operating mode, into the following categories:

  • Centralized                                                                                                          528
  • Non centralized (with 159 synchronized)                                                           859

Fixed-time system

It provides a fixed duration for green and red lights, regardless of the time of day, number of vehicles or if it is working day or not.

Activated systems

The activated system can be either vehicular or pedestrian: 

  • the vehicular system adjusts the duration of green lights according to the intensity of the traffic, due to the presence of sensors detecting the passage of vehicles
  • in the pedestrian system, there are "call buttons" - activated by the pedestrians - allowing to activate the green light for crossing.

Centralized systems

Every single traffic light is "the node" of a network of multiple installments and its regulation is correlated with that of other intersections of the same area so as to maintain a satisfying coordination.

The determination of the green and red light durations takes place by means of a processor that analyzes the traffic conditions of the network by identifying traffic jam situations and determining both the optimal duration of the individual systems, and the phase difference between the green light times of different systems for coordinated routes.

Centralized traffic lights have been installed along the main arteries of the city, on two tram routes and in some particularly critical areas. Centralized systems can also be activated.

Coordinated traffic lights

Coordination between different traffic lights on a main route that has centralised traffic lights, changes the operating system by using a “scheduled” method for the time length of the green light, in order to avoid that vehicles have to stop at every traffic light, ensuring the smoothest possible traffic flow.

Traffic lights with a countdown device for the pedestrian yellow light

The main target of the new traffic laws is to ensure pedestrian safety while crossing the roads. The current traffic light operating system establishes that a pedestrian can only start crossing when the light is green and finish crossing when it’s yellow.

The time length of the yellow light for pedestrians is calculated on the basis of how wide the road is and how long it would take to cross it for weakest users (elderly people, women with children etc), so that they can get to the other end of the crossing safely.

Pedestrian must not start crossing the road if the light is already yellow, he must wait for the green light.

To help pedestrians who are uncertain whether to cross or not with the yellow light, a “countdown” device has being installed at some traffic lights: it’s a display – installed next to the yellow light – showing the seconds left before the red light, so that pedestrians can cross the road safely.

Right now, 75 traffic lights in Rome are equipped with a LED-light countdown device – 32 pedestrians-only, 43 for both car and pedestrians.

 

Red light crossing detection

When the traffic light is red, the device takes two sequenced photos of vehicles that cross the stop line. The two photos are necessary to make sure the vehicle crossed the stop line with a red light. The system can detect the speed of the vehicle too.

This system has been installed at the following crossings:

  • via Cristoforo Colombo-via del Canale della Lingua, heading to Ostia

  • via Cristoforo Colombo-via di Acilia, heading to Ostia

  • via Cristoforo Colombo-via Pindaro, heading to Ostia

  • via Cristoforo Colombo-Circonvallazione Ostiense, heading towards the city centre

  • viale Marconi-piazzale Tommaso Edison, heading towards the city centre

  • via Tuscolana-via Palmiro Togliatti, heading towards the city centre

  • via Tuscolana-via dell'Arco di Travertino, heading towards the city centre

  • via Prenestina-via Palmiro Togliatti, heading towards the city centre

  • via Palmiro Togliatti-via Quinto Publicio, heading to Casilina

  • via Gregorio VII-piazza Pio XI, towards piazza di Villa Carpegna

  • via Leone XIII-piazza Pio XI, towards via Anastasio II

 

Road safety

 

Acoustic Devices for visually impaired people

Over the past few years Roma Servizi per la Mobilità has been installing acoustic devices for visually impaired people on newly installed traffic lights. There are currently 539 traffic lights equipped with these devices.

Traffic lights with audible signal devices have a button located in the lower part of the device that allows the request for pedestrian green light.

When the button is pressed, one hears a beep followed by another sound beep, confirming your reservation. The sounds are regulated against the background noise of the environment, and are differentiated according the phases of the traffic light (green and yellow light) of the pedestrian crossing.

 

Maintenance

Maintenance carried out on the devices is divided into: ordinary corrective, preventive and extraordinary.

  • Ordinary corrective maintenance means rapid intervention to sort out malfunctions of the devices. On working days, the maintenance must take place within two hours from the malfunction report, during holidays within up to five hou

  • Ordinary preventive maintenance includes preventive maintenance tasks necessary to keep all facilities in excellent conditions in order to ensure the highest level of efficiency.

Anything else that is not included in the ordinary maintenance is considered extraordinary maintenance. This includes reactivations due to damages or accidents, painting of the devices and updating them in accordance to the law etc.