Bridge Building tricks

[FM WarB]

I see no reference to size in the game manual's Engineer section. I do see: "Placing two or more Bridge Engineers will give you a higher chance of successfully completing the bridge." So three companies split from a batalion, all trying to build bridge on same hex get three rolls of the dice instead of just one. (You also have two companies left Over after the bridge is built.)
I like to think of this as like those Brits on the river Kwai becoming more efficient after Col. Nichols has properly divided their labours :-)