Safety-related concerns have been raised about another bridge in southeast King County, this one part of Southeast Green Valley Road.

County road officials said traffic on Patton Bridge has been restricted to one lane until further notice. The limit is in response to a routine county inspection in June that discovered deterioration of one of the concrete supports under the bridge.

This is a county-owned structure, unlike the state bridge on State Route 169 that was closed temporarily last week because a crumbling hillside affected the safety of that span and roadway.

Patton Bridge is still safe for crossing, but county road engineers want to keep as much weight off the damaged section as possible, according to Linda Thielke, a spokeswoman for the road services division.

There is no work underway to repair the bridge “because we need to do considerable engineering calculations to come up with the best fix. We hope to do the next stage of repairs before school starts in September and the salmon start coming upstream,” Thielke said.

A temporary traffic signal controls traffic flow over the bridge, which crosses the Green River. Motorists can take a detour via Southeast Green Valley Road, Auburn-Black Diamond Road and 218th Avenue Southeast.

The bridge normally averages about 12,000 car trips per day, officials said.

A State Route 169 bridge across the Green River near Black Diamond was declared safe July 3 by the state Department of Transportation (DOT) following emergency repairs of the roadway. The Kummer Bridge was closed part of last week while crews stabilized a slope under the south end of the bridge. The hillside, which is scheduled to undergo more work by this fall, had deteriorated to the point that the roadway was in danger of collapsing, according to DOT.

Crews will return to the site as early as September to build a retaining wall that DOT officials said is expected to be a permanent solution to the problem.

Meanwhile, in an unrelated county road project, the potential for collapse of part of Kanasket-Kangley Road is keeping the road closed near the intersection of Kanasket Estates Road for several more days until a culvert is installed.

The new culvert will replace an old one that’s failing and creating the potential for water to undermine and collapse the roadway. The location is east of Black Diamond.

The closure is scheduled to last until 5 p.m. July 16, county road officials said. Traffic is being detoured via Retreat-Kanasket Road and Kent-Kangley Road.