Serving Whitman County since 1877
Serving Whitman County since 1877
A new federal requirement to re-rate all bridges for weight limits will begin in Whitman County later this month with two consulting engineers hired at the end of June.
Nicholls Kovich Engineering of Spokane Valley and Sargent Engineering in Olympia will act as consultants for a federal requirement to update bridge ratings in light of changes in truck design which can mean heavier loads.
County bridges, which are inspected every year, were last rated for weight limits in the 1990s or eary 2000s.
Last week, the county received a full listing of 120 bridges it will be required to re-rate this year. This will include 22 bridges inside towns or cities.
Another 160 to 170 county bridges will be done in early 2018.
The federal Surface Transportation Program will pay 83.5 percent of the project’s estimated $353,400 total cost, with the county paying the rest from its road fund.
The new bridge rating requirements also aim to address newer special-haul vehicles such as concrete trucks or dump trucks with more axles spaced closer together.
“Over time, trucks get larger, heavier,” said Susan Kovich, principal engineer with the Spokane Valley firm.
New “super singles” tires are wider, single semi-truck and trailer tires as opposed to dual tires, which distribute weight differently. New trailer configurations also play a role in weight limits for roads.
Once the new ratings are complete, some bridges now without posting for special weight limits may be posted.
“We need to go back to the bridges that have already been built to check how much they can safely carry,” said Kovich.
Garth Meyer is a former Whitman County Gazette reporter.
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