a communication device arranged in the second vehicle and which communicates {HEAD ~ the position} of {TAIL ~ the second vehicle} as determined by said second positioning system to the first vehicle 
of
a communication device arranged in the second vehicle and which communicates { HEAD ~ the position } of { TAIL ~ the second vehicle } as determined by said second positioning system to the first vehicle
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH