That looks like a fairly light construction structure, and probably didn't weigh that much. The tire size/capacity (and they do overload them for these short low speed hauls) then is used to determine the number of tires required. Likely didn't weigh more than 20 tons (40,000 lbs.). Some of the weight was carried by the truck, say 10,000 lbs. 30,000 lbs can be carried legally on 12 tires, 3 axles of 4 tires. For a short low speed haul, 2 axles with 8 tires, sure would be enough. Interesting that the load got to the middle of the bridge before collapsing, saying that they almost had enough capacity to get across. :) Almost doesn't count except horseshoes. :) John La Rooy wrote: > On Fri, Jul 3, 2009 at 6:17 PM, Alan B. Pearce wrote: > > >> I am surprised it has only a set of wheels half way down the length. I would >> have thought it would have needed more wheels than that. >> >> > You were right - it did :) > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist