The Oklahoma Department of Transportation says a new study shows it is unlikely that a 4.6 magnitude or less earthquake in the state would damage any bridges or highways.
The $575,000 study by Infrastructure Engineers Inc. validated the State Highway Department’s inspection process, according to an announcement by ODOT.
“This is great news for Oklahomans concerned with the long-term effects of increased earthquakes in our state,” said Mike Patterson, ODOT executive director. “Our department has aggressively inspected bridges and infrastructure for the past few years and learned a great deal through this process about this relatively new phenomenon in our state.”
Infrastructure Engineers Inc. worked closely with the University of Oklahoma researchers over the past year and found no structural damage occurred on bridges after tremors less than 4.7 magnitude. ODOT said it means bridge inspections won’t be necessary following any earthquakes with a magnitude less than 4.7. The Department previously checked bridges after nearly every earthquake that measured at least 3.0 magnitude. Then ODOT consulted with the U.S. Geological Survey and the Oklahoma Geological survey and the protocol changed in mid-2014 to carry out inspections after every 4.0 magnitude quake within a 5-mile radius of the epicenter.
“We were conservative in our approach to bridge inspections, but now we have the science to know with more certainty that 4.0 to 4.6 magnitude earthquakes present no danger to transportation infrastructure in the state,” said Casey Shell, ODOT chief engineer. “This change in protocol allows the department to better focus its resources.”
Shell said the state transportation department has never found any structural bridge damage in the state due to earthquakes since the inspections started three years ago. He explained that the state’s bridges meet federal design standards, meaning they should safely withstand some degree of vibrations and movement.
The study will also mean changes to a post-earthquake bridge inspection manual used by inspectors across the state and will be shared by state agencies and government entities such as the Oklahoma National Guard and with counties and municipalities.
