Autostrade per l'Italia

Quarta corsia dinamica

The Dynamic Fourth Lane in A4

The innovative “Dynamic Fourth Lane” system makes it possible to manage the transition from three-lane plus emergency operation to a four-lane operation without an emergency, guaranteeing that the fourth lane can be used when specific traffic conditions occur on the section.

The overall project currently covers 9.3 kilometres of the A4 Torino-Trieste motorway north of Milan, between the Viale Certosa junction and the Cinisello Balsamo artificial tunnel. This section experiences traffic peaks of around 200,000 vehicles per day, three times the average recorded on the Autostrade per l'Italia network.

The technology platform, developed by MOVYON, manages 3 systems in a coordinated manner:

  • The ANALIZZO Traffic Analysis System, which allows constant monitoring of traffic through data processed by sensors in the field.
  • The Warning System, which immediately notifies users on the road of 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 on the wrong side of the road, queues. The occurrence of any of these events results in real-time alerts being sent to operators in the radio room and the emergency lane being closed to traffic. Monitoring is carried out using radar, laser scanners and cameras equipped with artificial intelligence algorithms that continuously scan the carriageways and traffic.


The Dynamic Fourth Lane aims to streamline traffic, improving the travel experience of users who travel the Milan section of the A4 Torino-Trieste every day.