Editor’s Note: The flooding associated with Hurricane Harvey in August 2017 far exceeded the conditions described in this 2015 story. The net effects on pavement quality are tertiary to the death and destruction of this storm, but the severe degree of potholes and other infrastructure deterioration will undoubtedly plague the region and impair rebuilding efforts in the months and years to come.
In late May 2015 Texas received enough rainfall to cover the entire state in eight inches of water. Together with the equally saturated state of Oklahoma, it was the Lone Star State’s wettest single month on record. The Oklahoma Climatological Survey said the overall May recorded rainfall was 14.40 inches, by far eclipsing the state’s previous record of 10.75 inches set in October 1941.
The rainfall, which spread over ten days, resulted in floods that caused $1 billion in property loss claims and another $3 billion in economic losses. At least 28 people died in the riverine and flash floods, which came on the heels of a severe multi-year drought.
Several weeks after the floods the secondary losses began to be tallied, including potholes and outright pavement loss – both attributable to the excess water.
For example, the Fort Worth Star-Telegram reported how car-size holes opened up on roads in Central Texas due to floodwaters passing under roads through culverts and storm drainage pipes, and where bridges had been wiped out by large debris such as floating trees crashing into them.
The damage included potholes, including one measuring 8 feet by 3 feet on a residential neighborhood near Fort Worth.
Reporter Jeremy Rogalski of television station KHOU in Houston reported that, “with last week’s heavy rains, all the water had nowhere to go.” An official from the city’s Department of Public Works explained in the segment that water everywhere was weakening asphalt and concrete, leading to deterioration. In general, excess water creates new potholes and makes existing potholes bigger.
Potholes typically form in areas where roads are wettest, such as dips under viaducts. This is pronounced in climates that experience frequent freeze-thaw cycles, but also in warmer regions where traffic, water and time conspire to undermine pavement.
Flooding conditions present road officials with a different set of problems. First responders have to assess – where and when they can – if emergency vehicles can travel safely over flood-damaged roads. This requires them to consider the different types of pavement over different compositions of soils in affected areas. When the first level of emergency is over, heavy repair vehicles may be needed; the impact of multi-ton trucks and other equipment on pavement that is newly lacking a substructure – dirt and gravel that has washed out – must also be considered in balance against the local economic impact of rerouting traffic through detours in order to preserve pavement.
As of this writing, a named tropical storm (“Bill”) is forming in the Gulf of Mexico and appears to be on path to cut right through the heart of Texas. The region’s drought may well be over, but rains could have their own lasting consequences in the form of potholes and other pavement deterioration.