April 25, 2008

Engineering firm calls for shoring up bolts on Boston’s Big Dig

BOSTON

The engineering firm about to complete the Big Dig’s stem-to-stern safety review says that the Massachusetts Turnpike Authority should implement a few more repairs to ensure all the tunnels are safe to the traveling public.

Wiss, Janney, Elstner Associates of Northbrook, Ill., said the fire suppression system in the Sumner Tunnel — especially the ventilation — should be replaced to better remove hot and toxic gases.

The firm also said about 180 undercut anchor bolts should be added in the Ted Williams Tunnel to shore up existing bolts epoxied into imperfect concrete or areas that are leaking.

In addition, 13 rows of strapping and about 900 more anchor bolts should be placed within about 250 feet of each end of the tunnel to guarantee epoxy bolts can’t slip free.

The existing bolts are considered sound, but they cannot be inspected, so engineers said the modification would be a “belt-and-suspenders” means of assurance.

They said the work doesn’t have to be done for up to five years, underscoring their confidence in the existing set-up.

“Yes, yes,” said Robert Rooney, the top public works official at the state’s Executive Office of Transportation, when asked whether the system is safe even without any of the proposed changes.

Wiss, Janney did not provide estimates of improvement costs, except to say the straps and bolts installation would be in the millions of dollars.

The engineers plan a final report to Governor Deval Patrick on June 27.

The review was triggered by the July 2006 collapse of the Big Dig tunnel ceiling that killed 39-year-old Milena Del Valle of Boston.

Then-Gov. Mitt Romney ordered a comprehensive examine not only of the $14.6 billion Central Artery/Third Harbor Tunnel project, but also the Tobin Bridge and the Turnpike Extension leading into Boston from the west.

Associated Press

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