He said the track chair is a cast iron “ring” (similar to a lazy Susan) upon which sits a variety of equipment.
“Essentially, the primary purpose of the track chair is to support the swing span,” he said about the bridge’s movable center section.
Verseckes said an initial evaluation of the track chair showed it was in relatively good shape and, with rehabilitation, it was expected to meet or exceed the design life of the improved structure.
“Unfortunately, upon dismantling of the machinery, it was discovered that the track chair contained micro cracks that could not be readily identified during the initial visual inspections,” he said. “It was determined that a new track chair would have to be designed.”
He said MassDOT and the contractor worked to speed up the design and and the work hours on the project were expanded to a 12-hour shift, seven days a week. Verseckes said that despite those efforts, the unexpected additional work resulted in the reopening of the bridge being delayed by about one month.
Verseckes said various people affected by the project — including officials from Haverhill, West Newbury, Merrimac and Whittier Regional High — met last week to review the issue of the delay.
“Included in the discussion were two proposals – one that would allow the project to achieve the original opening date in late August, but which would require daily lane closures afterwards to complete additional work items, and a second that involved continuing the current schedule with the bridge closed with substantial completion of the project being pushed out to late September,” Verseckes said.
“We are moving forward with the latter option, as many believed that the inconvenience and uncertainly of the lane closures over an extended duration (possibly through November) after reopening was less desirable than simply extending the period of full closure by one month,” he said.