This is also standard common curtesy on Japanese highways. The biggest part is drivers behind the original signaler will turn on their hazards to communicate ba

This is also standard common curtesy on Japanese highways. The biggest part is drivers behind the original signaler will turn on their hazards to communicate backwards in the chain. Thus everyone can anticipate the slow down before the slow down would be visible. It is a big deal in Japan where even the raised highways and especially tunnels under Tokyo are curvy.