Tunnel, Railroad Crossing, and Routing Restrictions
Hazmat routing rules keep dangerous loads away from tunnels, bridges, and populated areas. Many tunnels prohibit placarded hazmat entirely; others require permits or escort. The candidate must know to look for signs before entering a tunnel and to never enter a tunnel with a placarded load if prohibited. Railroad crossings require stopping for hazmat loads (except where exempt), looking both ways, and proceeding only when clear-never stop on the tracks. Routing may require designated hazmat routes; drivers must follow them and not take shortcuts through residential areas. Traps: questions claim you may enter a tunnel if you are in a hurry (no), or that you do not need to stop at a railroad crossing with hazmat (you do, unless exempt). Also know that bridge weight limits and clearance matter for cargo tanks. Rule of thumb: signs rule-if a tunnel or route is restricted, find another way. Worked example: A driver with a FLAMMABLE placard approaches a tunnel marked "No Hazardous Materials." The driver must not enter; instead, follow the posted hazmat detour or contact the shipper for an alternate route.