Commission considering repairs on Browns Park structure
January 28, 2010
The Moffat County Commission reviewed possible improvement plans Wednesday to the Browns Park swinging bridge on Moffat County Road 83.
The commission closed the bridge in November 2009 after county road and bridge staff and a state engineer determined the structure's support cables too brittle for regular use.
The commission enlisted the services of Diversified Consulting Solutions to examine the state of the bridge and establish which repairs are most necessary.
Dan Giroux, principal/land division manager for DCS, presented the company's findings and repair ideas to the commission in a Wednesday meeting.
Out of 66 cables on the bridge, DCS found six strands broken, which Giroux said was not unexpected.
"Any kind of kinking in these strands will ultimately break over time," he said.
Giroux recommended the replacement of all bridge cables, as well as the reinforcement and redesign of the concrete anchor blocks on each end of the structure.
The current anchor blocks are 9 feet long by 3 feet wide, and the attaching cables run into the ground at the point where the blocks are buried.
Giroux's plans to change the blocks are to widen each to a proposed 20 feet by 11 feet and to raise the blocks out of the ground enough so the cables are free of soil, which Giroux said deteriorates them.
The raised cables would stay at the same angle but would be 2-feet higher, based on Giroux's design.
The higher positioning would run to the bridge towers, which DCS determined needed to be "bolstered." Giroux proposed the attachment of a straddle on each tower, a pair of metal wheels on either side about 8 inches in diameter, where the cables will rest.
Giroux said the straddles will not necessarily decrease the tension of the cables, but they will become the new "key wear point."
By using this method, he said the cables will receive less stress at the points where they meet the tower, and the wheels, which are less expensive to replace, will take the burden.
"It's much kinder and gentler on the strand," he said.
The commissioners agreed with many of Giroux's points, but Commissioner Tom Gray voiced concern that DCS' estimates were too expensive.
The estimated cost for the improvements to the anchor blocks, cables and towers was $215,894.64.
Total repairs are estimated to cost $462,787.44, which includes $246,892.80 for the upgrade of the bridge's deck, beams, stringers and safety rails.
Gray and fellow Commissioner Tom Mathers agreed that the latter part of the proposal was not necessary in bettering the structure's condition and ensuring the weight limit was at an acceptable level. Traffic in the area has been rerouted since the bridge was closed.
"We're dealing with basics," Mathers said.
Gray said agreeing to the entirety of the estimate would not be a good use of county funds.
"The other part of this plan is just a 'phase two' if we ever need it," Gray said.
The Colorado Department of Local Affairs provided $65,000 of the money budgeted for the bridge improvements on the condition that the money be used for repairs.
Giroux said he could refigure the plans based on the county's needs.
"I just need to know what direction we're going in," he said.
The commissioners took no official action Wednesday, but they decided to look further into the $215,000 plan, pending additional cost evaluation.
In figuring the costs and lengths for the cables involved, Giroux and the commissioners will seek out contractors in February.
Giroux said the swinging bridge is the fifth suspension bridge on which he has worked.
"It's a fun project, and it's good for county residents," he said. "The bridge is a well-known structure, and it can be challenging to find cost-effective ways to work on it."