Bridge Collapses During TX Flooding
Flooding of the Llano River, a tributary of the Colorado River located in central Texas, caused the collapse of the RM 2900 bridge on Tuesday (Oct. 16). The concrete and steel two-lane span was built in 1969, designed to withstand a 50-year storm.
Officials say that the river crested at 39.91 feet—just below 1935’s record high of 41.5 feet—and rushed around the bridge for hours. On Tuesday, Texas Gov. Greg Abbott ordered the Texas State Operations Center to increase its readiness level for flooding and officials evacuated residents within a quarter-mile radius of the river. While no one was reported injured in relation to the bridge, the flooding has claimed at least one life.
According to the Austin American-Statesman, Texas has 53,000 bridges, more than any other state. Many of these were built in the 1950s in accordance with available weather data from the same period, but over the past several decades there has been an increase in rapid rain events.
Travis Attanasio, a civil engineer located in the Fort Worth area who also serves as an American Society of Civil Engineers officer, told the American-Statesman that most of the bridges built on roads managed by the Texas Department of Transportation were designed to withstand 25- to 50-year storms. Interstate highways were designed to withstand 100-year storms (a storm that has a 1 percent chance of happening in a year based on weather data).
Current available information is being re-evaluated to reflect the increase in rainfall, and many areas in Texas are moving to update flood plain maps.
TxDOT spokesperson Chris Bishop told the American-Statesman that the RM 2900 bridge had been built with the assumption that water levels in the area would stay stable.
Attanasio noted that footage of the collapse seems to show that the flooding was what did the bridge in, the structure likely failed due to the accumulation of debris, or some kind of large debris hitting one of the support columns. Replacing a bridge of this kind is likely to cost roughly $20 million, said Bishop.
According to an announcement from TxDOT, the bridge is to remain closed indefinitely. Routine maintenance was carried out in 2010, and the span was found to be structurally sound during its last inspection in 2017. (TxDOT does inspections every two years.) This was also the first time water had breached the structure. Once water recedes, the department will inspect the bridge, and repairs will be expedited.
Roughly 5,600 drivers use the bridge daily.