{TAIL ~ The control system} guides the moving travel zones through the empty zones of {HEAD ~ the cross roads} without stopping 
{ TAIL ~ The control system } guides the moving travel zones through the empty zones of { HEAD ~ the cross roads } without stopping
TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH