ABSTRACT
The emphasis for the highway industry in the United States has shifted to maintenance, rehabilitation and conserving the existing road network. Bridges are a vital link in the highway system and, in part, because of their conservative design, bridges have been allowed to deteriorate over many years because of deferred maintenance and repairs. There are some 600000 bridges in the United States under a wide variety of ownerships and control. The Federal Highway Administration now estimates that more than 200000 bridges are inadequate and lists over 125000 as structurally deficient on the National Bridge Inventory System. There are some 5000-8000 replacements per year, so that for the foreseeable future the inventory of bridges in the United States will contain numerous structures incapable of carrying today’s standards of truck weight.
