A control system controls a pair of vehicles in coordination to traverse a respective pair of trajectories. The control system is configured to specify a plurality of successive waypoints, a safe stopping interval and an intermediate interval greater than the safe stopping interval, and exchange waypoints between vehicles. The system controls each vehicle in coordination with the other, senses a rate of exchange of waypoint data between the vehicles, and determines the safe stopping interval. The control system updates positions with additional waypoints as the respective vehicles pass by waypoints of the forecasted trajectory, determines the length of the forecasted trajectory remaining and compares it with the intermediate interval and the safe stopping interval. The system generates a warning signal if distance is less than the intermediate interval, and if the distance is less than the safe stopping interval, stops within the safe stopping interval.