The new $9.3 million temporary Lagoon Pond Drawbridge would not open during a test on April 5. The cause may have been warmer temperatures that caused the metal bridge to expand, according to a state Department of Transportation (DOT) spokesman.
The problem resembles occasions when the old, 1930s drawbridge, temporarily replaced by the temporary bridge, failed to open or close because of expanding metal in hot weather. Construction is to begin soon on a permanent bridge, at a projected cost of $35.7 million.
Engineers representing the bridge manufacturer and construction contractor cut off a small section of the metal bridge where the bascule leaf (the part that rises) meets the bridge deck. The drawbridge has functioned without incident since the surgery.
“Sections of the filler deck plates were in contact with the bascule leaf,” said DOT spokesman Adam Hurtubise. “An initial review indicates that the problem is likely related to expansion because of the higher temperatures. The bridge was initially assembled during very low temperatures. The manufacturer is currently working on a report of the incident and what actions should be taken to prevent a repeat of the problem.”
Veteran bridge tender Bob Maciel said the engineers did not discuss possible causes with him. He said the bridge worked flawlessly during testing in early January, just before the bridge opened to traffic.
“The only thing I can think of, the temperature was 63 degrees,” Mr. Maciel said. “Before when we ran it, it was 28 to 32 degrees.”
In most bridges, expansion joints are designed to account for all possible temperature ranges.
“When constructing a conventional bridge, the expansion joints are positioned in the field and are set based on temperature,” Mr. Hurtubise said. “This particular bridge does not have conventional expansion joints and is constructed of prefabricated truss sections assembled to fit the substructure. The temporary bridge design was developed and went through changes during construction.
“Because of the aggressive schedule needed to complete the job, it was necessary to do much of the work during inclement weather. Once the bridge is erected, standard filler plates are used to fill gaps that could cause a safety hazard. Because of the extremely cold weather during final erection of the bridge, the expansion was significantly greater than anticipated, resulting in the contact. No apparent damage occurred to the structure, and all necessary adjustments will be made by the manufacturer.”
Mr. Maciel discovered the problem when he received a request to schedule a bridge opening for April 9, so two boats could exit Lagoon Pond. Four days before that, he went to the bridge to do a test. But instead of a routine test, loud alarms and flashing lights greeted Mr. Maciel.
“It would scare you right out of your skin,” he said. “It’s like a siren noise inside the building. We got a dashboard we work with there. All the lights on that thing flash, ‘emergency, emergency’.”
Mr. Maciel immediately called DOT to report the problem.
The bridge was manufactured by ACROW Corporation, and constructed on site by Pihl, Inc. Under the watchful eyes of DOT officials, engineers from those two companies worked to repair the bridge for parts of two days. On April 8, with Mr. Maciel at the bridge controls, another test lift revealed more work needed. As the bridge began to lift, there was a loud screeching sound.
“It hit on the way up, when it got off the ground about three feet,” Mr. Maciel said. “It fetched up. It hit but didn’t set the alarm off. As I was watching it (the bridge) shifted as it hit.”
When Mr. Maciel lowered the bridge, it appeared to hang up, then drop with a loud crash back into place, flush with the roadway. The entire bridge structure shook noticeably. Engineers went back to work with metal saws, crowbars, and elbow grease.
Mr. Maciel said he lifted the bridge later that day without incident, allowing two vessels to pass beneath through the channel into Vineyard Haven Harbor.
“There is concern about the situation, and what the future holds,” Melinda Loberg, chairman of the Lagoon Pond Bridge committee, said this week. “I would say it’s a tiny glitch, but I’m not an engineer. I didn’t get the impression from Mass DOT that their concern level was elevated.”