The Federal Highway Administration is requiring local governments to evaluate their bridges for new load ratings by Dec. 2017, to ensure that the structures can handle modern vehicles that are designed to haul heavier loads.
Thurston County Public Works is about a third of the way through checking those weight limits on the 119 roadway bridges in its inventory, according to civil engineer Matt Unzelman.
However, the county is going to hire an outside firm to do some of the inspections.
The Board of County Commissioners voted 3-0 Tuesday to hire Exeltech Consulting Inc. of Lacey to conduct that work on 10 structures, ranging from the Old Highway 101 Bridge to the Mud Bay Bridge. The amount of the contract is $87,000.
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“Some of our more structurally complex bridges are included with these 10 bridges,” Unzelman told The Olympian. “We just need a different level of expertise.”
The ratings will determine if the county needs to add a weight limits to some of its structures, he said.
County manager Cliff Moore described the work as routine, but said it’s an important long-term process for the county.
“Like most jurisdictions in the nation, we are trying to keep on this issue,” he said.
The money will come from the county’s road fund, and will include the following structures. (Size and inspection information was listed in the county’s 2014 Bridge Index.)
• James Road Bridge (culvert), known as J-1, which goes over an overflow channel, was built in 1985. The 25-foot-long structure was given a 98.19 sufficiency rating during an Aug. 8, 2012, inspection.
• Littlerock Road Bridge, known as L-5, which goes over a ditch, was built in 1960. The 20-foot-long bridge was given a 49.66 rating during a Nov. 21, 2013 inspection. Crews made some emergency repairs on the bridge this spring for scour and cracking. It is just down the road and the same design as the L-4 Bridge which is undergoing a complete replacement due to structural deficiencies.
• Mud Bay Bridge, known as O-4, which goes over Mud Bay, was built in 1978. The 208-foot-long bridge was given a sufficiency rating of 77.02 during a Sept. 27, 2012 inspection.
• Old Highway 101 Bridge, known as O-3 which goes over Perry Creek, was built in 1958.The 105-foot-long bridge was given a sufficiency rating of 80.31 during a Sept. 14, 2012 inspection.
• Oyster Bay Culvert, known as OB-1, which goes over Schneider Creek, was built in 2010. The 20-foot-long bridge was given a sufficiency rating of 85.8 during a June 12, 2012, inspection.
• Steamboat Island Bridge, known as S-7, which goes over Totten Inlet, was built in 1982. The 706-foot-long structure was given a sufficiency rating of 68.73 during a Sept. 14, 2012, inspection.
• Holmes Island Bridge, known as H-3, which goes over Long Lake and was built in 1962. The 53-foot-long bridge, and was given a sufficiency rating of 54.26 during an Aug. 7, 2013 inspection.
• Nisqually Cutoff Bridge, known as N-1, which goes over an overflow channel, was built in 1936. The 92-foot-long structure was given a 74.48 sufficiency rating during an Oct. 4, 2012 inspection.
• Old Pacific Highway Bridge, known as O-11, which goes over the Nisqually River was built in 1998. The 320-foot long structure was given a sufficiency rating of 95.38 during a Sept. 12, 2012 inspection.
• Reservation Road Railroad Bridge, known as R-1, goes over a railroad and was built in 1993. The 331-foot-long bridge was given a sufficiency rating of 94.49 during an Aug. 9, 2013 inspection.