The Dynamic Fourth Lane in A4

The innovative "Dynamic Fourth Lane" system is a project of the Autostrade per l'Italia Group, carried out on the Milan section of the A4 Torino - Trieste motorway, and has become a reality thanks to the development and application of a sophisticated technological system that allows the transition from three lanes plus emergency lanes to four lanes without emergency lanes, on a section that records peaks of around 200,000 vehicles per day, three times the average recorded on the network.

The aim is to ensure greater traffic fluidity by applying innovation and technology to allow the infrastructure capacity to be adjusted, in accordance with the principles of sustainability and urban regeneration.

Open to traffic between the Cormano junction and the Viale Certosa junction in both directions, it offers a unique response to the need to increase the capacity of the section despite the impossibility of widening the carriageway due to its proximity to densely populated areas.

The technological platform, developed by MOVYON, guarantees the use of the available fourth lane and temporarily opens it to traffic when specific conditions occur on the section; these conditions are calculated through the processing of data acquired by using sensors and algorithms for analysing and forecasting vehicle flow.

The programme coordinates three activities:

Traffic analysis, which constantly monitors traffic using data processed by sensors.
The signalling system, which immediately notifies users of any changes in the use of available lanes and speed limits.
The Automatic Incident Detection (AID) system, which detects all potentially dangerous traffic events, such as vehicles stopped in the dynamic lane, vehicles travelling in the wrong direction, congestion. If any of these events occur, real-time alerts are sent to operators in the radio room and the emergency lane is closed to traffic. Monitoring is carried out using radar, laser scanners and cameras equipped with artificial intelligence algorithms that continuously scan the road and traffic.

In addition to providing a better travelling experience, the new infrastructure will benefit the environment: each hour spent using the dynamic fourth lane on the planned ten kilometres saves an estimated 1.5 tonnes of CO2. The upgrading programme also includes a number of local initiatives, such as the Cinisello Balsamo soundproof tunnel, the upgrading of the Dalmine junction and the redesign of the Sesto San Giovanni junction, which will reduce noise pollution and improve the urban road network and access roads to the motorway system.