Moffat commissioners start work for Swinging Bridge rehabilitation
March 4, 2010
The Moffat County Commission took another step Tuesday in its effort to rehabilitate the Swinging Bridge.
The commission voted, 2-0, to purchase two new cables to stretch across the bridge. The cables, which will be the same diameter as the current ones, will cost $14,855 each and will arrive in about three months.
The Swinging Bridge, built in 1954 and located in Browns Park in western Moffat County, provides access to public lands for hunting and recreation, Moffat County Commissioner Tom Gray said. It has been closed since November 2009.
The original cables had several broken strands where they meet the towers as a result of the bridge's saddle design. Over time, stress placed on the cables bent them into cracking.
These breaks in the strands weakened the overall structure and forced county road and bridge staff to close the bridge.
The county commission also voted, 2-0, Tuesday to waive the bid process and award Diversified Consulting Solutions, based in Westminster, the engineering contract for the repairs.
DCS had been working with the commission since the bridge's closing and provided the commission with several options and designs for the repair.
After considering several repair packages, the commission decided on the most cost-effective options, Gray said.
The rehabilitation project will outfit the bridge with new cables, replacement of all hanger cables, enlarged and redesigned anchor blocks and a new saddle design, Gray said.
The new improvements will upgrade the bridge from its previous 3-ton load capacity to a 23- to 25-ton load capacity.
The new anchors will sit on top and behind the old anchors and will be about three times as large. They will feature a new design that places the two main cables above ground connected to a beam inserted in the concrete anchor.
The old anchors are designed so that the cable is cemented into the 9-foot-long, 3-foot-wide block. This design prohibits the cable from being swapped because of damage without replacing all the anchors. Being buried under soil also rusted the cables, further weakening it.
Work on the anchors will start in a few weeks after the commission bids for the concrete needed.
The new saddle design will hold the two main cables in place over an 8-foot diameter half circle. It is hoped the new design will reduce the wear on the cable that occurred with the last design, leading to its eventual break, DCS land division manager Dan Giroux said.
The four new saddles are being made in-house and will cost about $5,000.
Despite early estimations placing the cost of the repairs at about $460,000, Gray said the cost will total about $100,000 for materials.
The county will save about $100,000 by having its road and bridge department complete the repairs.
DCS will provide the road and bridge department with advice on how to go about implementing the repairs, engineering designs for parts and any processes they are not familiar with, Gray said.
The commission hopes to have the project completed in early summer.
The county received a grant from the Department of Local Affairs for $65,000 to help cover the cost for materials.
All told, the county will spend about $35,000 on the project, Gray said.
The commission did not pursue the earlier presented options to replace the bridge's deck, beams and safety rails, which were deemed "not necessary."