Traffic is flowing again on Interstate 80 after a large hole opened up underneath the thoroughfare's eastbound lanes in Council Bluffs on Wednesday night.
Road crews worked all night, breaking up the surface pavement, filling in the roughly 6-foot-wide and 4-foot-deep hole and paving over it with quick-set concrete.
By 8 a.m. Thursday — roughly 12 hours after construction workers discovered the hole near the 24th Street exit — commuters were driving on the new pavement.
Dave Dorsett, resident construction engineer for the Iowa Transportation Department's office in Council Bluffs, said Thursday that the road is safe and the fix permanent.
“I don't think there's any reason for worry or concern'' about further damage, Dorsett said.
The construction workers who discovered the hole were putting in a drainage pipe near the 24th Street exit, said Troy Jerman, a Transportation Department engineer for southwest Iowa. The shoulder crumbled and the traffic lanes appeared imperiled.
A construction worker called 911 around 8:15 p.m., and authorities shut down eastbound travel. No injuries or crashes were reported.
The void did not extend under the westbound lanes so traffic there continued largely unaffected.
Officials haven't pinpointed the cause of the hole. But Dorsett said ongoing reconstruction of the Interstate in the area and last week's heavy rains and runoff could have contributed to its formation.
The hole formed along a stretch of the Interstate in the Bluffs that has been under construction for a couple of years. About 15 years of work remains to be done on the nearby Interstate system, Dorsett said.
The state was fortunate that Peterson Contractors Inc. of Reinbeck, Iowa, discovered the void and made the necessary repairs, he said.
Engineers decided against filling the void with mortar, which would take too long to set up. Instead, crews tore up the old concrete section and used a “special back fill'' that includes a base material of crushed rock, he said.
The crushed rock already was on site because it is being used as part of the I-80 reconstruction work.
The crews then patched the I-80 section with a high-end cement mix designed for heavy-traffic areas. It cures in about five hours.
“Obviously,” Dorsett said, “our primary concern was to restore traffic as soon as possible.”
Wednesday night, engineers estimated that eastbound I-80 wouldn't reopen until at least late Thursday afternoon.
“We were very fortunate,'' Dorsett said. “Everything came together very well.''
On Wednesday night, after they closed the eastbound Interstate, authorities turned around dozens of semitrailer trucks and other vehicles near the site of the collapse, directing them onto the entrance ramp and then onto 24th Street.
Cars and trucks backed up for several blocks at the intersection with Veterans Memorial Highway, as a long line of traffic waited to turn east.
Construction on the four-mile stretch of freeway shared by I-29 and I-80 on the south side of Council Bluffs is part of a long-term expansion and realignment of the Interstate system in the city.
Much of the system is being rebuilt to replace outdated structures and to accommodate traffic demands.