In previous work, we used an extended version of timed automata to build safe controllers for autonomous car manoeuvres like changing lanes or crossing an intersection. These automata use formulae of Multi-lane Spatial Logic as guards and invariants and have special controller actions for car manoeuvres. As a case study, we now adapt our approach to formalise a multi-hop communication protocol for hazard warning for highway traffic scenarios. We prove that, if a car detects a hazard, this information timely reaches all cars for which it is relevant via a communication chain so that they can avoid colliding with the hazard.