Freedom—October 23, 2020—The trouble-plagued project to replace the Danforth Brook Bridge on Ossipee Lake Road took another hit this week when the Freedom Select Board voted to close the span to all traffic until further notice.
The bridge is likely to remain closed through December, the town said.
Construction work on the $1.1 million project was aborted on September 30 after bore-hole tests revealed the load-bearing capacity of the soils surrounding the bridge was less than what is required in the design. The town kept the span open to passenger cars but banned trucks, saying the remaining section of the old bridge had been compromised by work on the replacement structure.
The closure of the bridge to all traffic, which is effective on Monday, October 26, is necessary in order to implement a solution to the load-bearing issue.
In a plan developed by the town’s construction administrator, CMA Engineers of Portsmouth, and GZA Engineering of Portland, a ‘densification’ technique will be used to increase soil capacity at the site. An initial test of the technique convinced the town it was the most cost-effective way to complete the project before winter.
Closing the bridge during the process will help ensure that the soils under both sides of the bridge footings are consistent and the span settles evenly, according to town administrator Ellen White.
White said the town recognizes the closure will be a “huge inconvenience,” but said safety services will not be interrupted. Action Ambulance has a base station on the town line between Tamworth and Madison on Route 41, and fire coverage can be provided by the West Ossipee Fire Department through mutual aid.
White said the decision-making process during the past month was “fluid and fast moving,” with the State of NH DOT, which has to approve any work order changes, working with all parties in an “extremely cooperative” manner.
The bridge project was approved a year ago after a decade of delays in obtaining state funds. Work was supposed to commence at the end of spring melt this year and be completed by November. But in mid-June, a design flaw in one of the bridge’s wing walls was found during a review by the construction engineering firm.
Addressing the flaw required new design documents and an amended state wetlands permit, which delayed the construction start date to August 10. Work began but stopped on September 30 after the load-bearing capacity issue became apparent.
The heavily-used bridge was built in 1925 and is long past its 50-year life expectancy.
White said the town believes the end-of-December completion date estimate is realistic.
“We are still awaiting the updated construction schedule, but it seems the densification technique is very predictable in its results based on the test area, and…all of the precast components that have been manufactured can be used with no new re-fabrication or down time.”
White said work could continue through the winter months if necessary, but “there is no plan to have this bridge closed through the winter.”