keep the distance; beware of the car in front
Fixed expression seen on road surface markings and signage, warning drivers to maintain a safe following distance to avoid rear-end collisions.
The road surface on the expressway had 'Keep the distance' written on it.
追突 means 'rear-end collision'; 追突注意 is the full warning phrase.
車間距離 refers to the distance between vehicles; 追突注意 is the imperative warning to maintain it.
Compound of 追突 (rear-end collision) and 注意 (caution, warning). A modern traffic-safety phrase.