Managed switches for greater safety and availability in the Cholfirst Tunnel

The system integrator, Ticos Engineering & Software AG, specializes in tunnel and traffic control systems. The operating and safety equipment installed in the tunnels normally ensures that the traffic flows smoothly. But if there is a fire or accident, these technical systems can also save lives.

The section of the Swiss A4 highway between Schaffhausen-Nord and Flurlingen includes several tunnels. It has been in operation since 1996, meaning that some of the technology installed at that time no longer meets the current requirements. Therefore, the Swiss Federal Roads Office (FEDRO) initiated a refurbishment program to increase tunnel safety. Ticos was awarded the contract for the conversion as well as the modernization of the operating and safety systems, including those in the 1260-meter, three-lane Cholfirst Tunnel.

To ensure that the work had as little impact on traffic flow as possible, the control engineering system was modernized in stages during ongoing operations. The system controller and several local PLCs were replaced. The allocated control cabinets are located in the engineering rooms or subdistribution centers of the two tunnel portals. The lane signals are connected to the traffic control engineering system here. The Ticos employees switched the signals from the old controller to the new controller. Additionally, an Ethernet-based communication system was also installed at the field and control level.

A redundant Ethernet ring based on singlemode fiberglass technology was installed to cover the large distances involved and to ensure high availability. Ticos selected managed switches from the FL SWITCH 22xx series as the infrastructure components. The main reason was the easy handling of the devices, which can be set up in a redundant ring topology without further configuration. Since the control network had to be set up quickly, it was advantageous that no further time-consuming configuration work was necessary.

The switches have two singlemode fiberglass interfaces with SC Duplex connectors, as well as six twisted pair copper interfaces with RJ45 connectors. The singlemode ports are connected to the fiberglass installation through fiber-optic cable patch fields. The fiberglass cables run between the tunnel portals in the service duct below the carriageway. There, the switches are mounted in the transverse control boxes and are coupled to the fiberglass ring. The main and local controllers installed in the substations are connected to the switches through RJ45 ports. The components are installed in the tunnel portal engineering rooms. Switches with singlemode uplinks are expanded in the substations with versions that have eight twisted pair ports so that further communication devices can be integrated into the network.

While the switches installed in the engineering rooms can be accessed easily, the devices installed in the service duct can only be reached after a long walk. Accessing the switches – through which, for example, the rerouting signals are controlled – installed on the masts and gantries in the entrance zones and in the open stretches also involves considerable effort. For this reason, the Ticos employees can assign an IP address over the network using the central Network Manager startup tool. Should further settings be necessary, they can also be configured with the software. Employees can thus configure all of the installed switches and perform diagnostics from the engineering room.