The current definition of the aggregations "headway" (package "TrafficHeadway") is ambiguous. One needs to add this measure is measured from the head of one vehicle to the head of the continuous vehicle.
Done. New definition of Trafficheadway is now "Averaged measurements or calculations of traffic headway, i.e. the distance or time interval between vehicles. This measure is measured from the head of one vehicle to the head of the following vehicle."