The posts 64 can be further designed as {HEAD ~ bumpers} against {TAIL ~ accidental truck impact} 
The posts 64 can be further designed as { HEAD ~ bumpers } against { TAIL ~ accidental truck impact }
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL