On the approach to tunnels, a sign will usually show a local radio channel. This should give a warning of any incidents or congestion in the tunnel ahead. Many radios can be set to automatically pick up traffic announcements and local frequencies. If you have to tune the radio manually, don't be distracted while doing so. Incidents in tunnels can lead to serious casualties. The greatest hazard is fire. Getting an advance warning of problems could save your life and others.