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