Came down Springfield road yesterday , popping into town too get some bits and there’s a foreign truck at bridge , I assumed he was deciding what too do ( how too turn round ) , as he obviously couldn’t get under bridge , when lights changed and cars pulled out to go past him and under bridge he’s measuring bridge with a stick 
, the heights are clearly signposted on bridge , seemed strange too be measuring it , never seen it before , they normally just turn round with assistance of cops
Maybe the height of the bridge didn’t match what his atlas said, so was just checking which was wrong.
At least he didn’t hit it! 
I have measured a bridge height before, but that was because it looked low, but wasnt marked. (On a quiet country road). Maybe in this case he was close to marked height and was seeing if the Actual height was/wasnt enough to pass under? Wouldn`t want to get into a situation like that in the first place, to be honest, but as E8B says better to measure with a stick then with the trl headboard.
That bridge is eleven foot six inches (I duck when I go under in my car 
) so no amount of measuring is gonna change the fact that his taut/tilt/fridge ain’t gonna go under it!