Many of the world's most challenging construction projects have involved the construction of tunnels in mountainous regions. The tunnels are needed to create usable and efficient highway and railway systems, with some tunnels stretching 20 kilometers or longer.

In fact, for tunnel applications, the length of the tunnel is often the main factor that determines the complexity of the monitoring system that will be used. Many different tunnel systems must be monitored, including the fan control system, fire control system, sensor system, alarm system, communication system, surveillance system, and speed-monitoring cameras. In the past, the need to monitor so many independent systems had a huge effect on cost, since each system required its own cabling. Now, however, all systems can be connected to an Ethernet network, which makes it much easier to set up, configure, and maintain the tunnel? various monitoring systems from central control center.

Consider the traditional 2-way tunnel as an example. Sensors are installed in the tunnel to collect data and trigger alarms, a fan system is used to control air flow, and a surveillance system and speed-monitoring cameras are required for safety reasons. The system diagram shows a local control center near the tunnel entrance, and a remote control center is located far away from the tunnel. Therefore, a reliable long-haul network that is used to communicate between the tunnel monitoring system and the control centers is required. Furthermore, different sub-systems in the tunnel might have different numbers of devices, so a network must use Ethernet switches with different numbers of ports. MOXA provides the EDS-505A/508A 5- and 8-port switches for connecting to devices, as well as switches with a larger number of ports, such as the EDS-518A and EDS-726 series that are often installed in the control center. If you need more fiber ports, the IMC-101-S-SC media converter can be used to extend transmission distance, and also create more versatile network applications.

It is crucial to pay close attention to the cabling needed for tunnel monitoring systems, particularly since the transmission distance between two nodes is usually greater than 100 m. Multi mode optical fiber can help make long-haul transmission more reliable, by making it possible to transmit data up to 4 or 5 km. This type of topology makes it easier to install the cables on both sides of the tunnel?ot only for safety reasons, but also to reduce risks. A single mode switch or media converter is especially useful for connecting the local network to the remote control center. MOXA? Turbo Ring and Ring Coupling functions can be used to reinforce the reliability of network communication, and ensure failure recovery in less than 300 ms.