Posted by Sherman in Idaho [72.47.153.105] on Thursday, January 16, 2014 at 14:50:08 :
In Reply to: 3 tons - Bridge plate posted by Gordon_M [2.28.25.7] on Thursday, January 16, 2014 at 13:45:26 :
On the "new" bridge weight plates, you put a top plate with "C" (for "combination") on it if it's for truck plus trailer.
I think the system started out with just the gross weight in tons, but then the engineers got hold of it and refined/complicated it based on how much weight is on each axle, and how close the axles are, in order to better reflect the actual stress a given truck puts on a bridge. There's an elaborate lookup table now that tells you what number to put on your bridge weight plate based on what kind of truck and trailer you have and how much load it's carrying.
The idea is still that before the convoy moves, the engineers are supposed to mark all bridges with similar signs saying what their maximum load rating is, and if the number on your truck is less than or equal to the number on the bridge, you're safe to cross.