HOLDING IT TOGETHER : FHWA PLANS STRATEGY FOR MAINTAINING BRIDGES

This article presents the first in a three-part series about the Federal Highway Administration's (FHWA's)proposed aggressive research and technology push to develop new ways to preserve existing bridges and build new ones that will last longer. This article describes the FHWA's efforts to create and inventory of existing bridge stock and generate suggestions for preserving it in the most cost-effective way possible. The program's unofficial name is Bridges for the 21st Century. Data in the FHWA's National Bridge Inventory show that there are more than 480,000 bridges and 110,000 tunnels and culverts. The mean age of all U.S. bridges is 42 years and rising. Degradation from de-icing salts and nearness to marine environments is a leading cause of bridge failure. Another is the as-built structure becoming inadequate for the loads it must carry. In the past, bridge owners neglected preventive repairs until bridges had to be replaced. The FHWA is encouraging proactive stances. Its proposed Long-Term Bridge Performance program would monitor 1,000-2,000 selected bridges over 10 to 20 years to provide a cross-section of bridge types. Each would be instrumented and monitored.