CLAYTON -- A road supervisor responsible for keeping an eye on the safety of travel conditions in east Contra Costa County performed his job exceptionally well Tuesday morning, and Contra Costa Public Works officials said a potential disaster on Marsh Creek Road was avoided as a result.

Crews were expected to complete construction of a temporary bridge on the road between Pine Lane and Deer Valley Road by 5 p.m., after the supervisor noticed a sinkhole developing along the shoulder of the road, a Public Works official said.

"He was just doing his job, driving around and making sure everything was safe," said Joe Yee, a manager for the county's Road and Flood Control Maintenance Division and a spokesman on the incident. "He noticed that something just didn't look right, and when he investigated further, he saw that a sinkhole was starting to form."

Officials closed the road in both directions after the discovery at approximately 8:30 a.m.

Crews used metal plates to act as a bridge, a temporary solution that will last until early 2013, when permanent repairs will be made.

"This will be temporary, and we will monitor it closely, especially with more rain anticipated to come," Yee said. "It is safe."

Big-rig trucks will be detoured around the sight, Yee said, but traffic will not have any other restrictions.

Officials were still investigating what caused the sinkhole, but it appears to be at least partially due to the recent rains, Yee said.

Contact Rick Hurd in Walnut Creek at 925-945-4780 and follow him at Twitter.com/3rdERH.