The Effects of Scouring on Highway Bridges.

The New Mexico Department of Transportation is responsible for the safety of highway bridges over rivers and arroyos in the state, but what are its methods and how does its personnel determine if a bridge is safe? For this, they have turned to the University of New Mexico Department of Civil Engineering, which has found a way to test the depth of the foundations of several bridges.

Two professors and their graduate students spent several months looking at bridges over rivers and arroyos for signs of scouring. 'The primary issue here is increasing safety of bridges," says Arup Maji, professor of civil engineering. "What they wanted to know is whether we could develop a method to determine the depth of the footing or foundation below the surface."

The Federal government requires that all highway bridges be examined to determine whether water flowing around the foundations has weakened the structures. For instance, there was the abrupt failure of a major bridge on Interstate 10 near the Arizona-California border in the summer of 2015.

State transportation departments must certify to the Federal government that they have examined the bridges and that the foundations are adequate to support both the traffic and the structure of the bridges themselves. Maji indicates that most of the highway bridges they are interested in were built more than 60 years ago but, over that time period, many things have changed, including, in some cases, the riverbed itself.

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