A Big Dig ramp, closed amid safety concerns in the wake of the deadly collapse of a nearby tunnel ceiling, will reopen at midnight Tuesday, Gov. Mitt Romney said.

The eastbound ramp funnels traffic toward the Ted Williams Tunnel and Boston's Logan International Airport, and is key to easing traffic congestion originating south of the city.

The ramp was closed shortly after an accident July 10 that killed a 39-year-old woman as she and her husband drove through a connector tunnel and their car was crushed by 12 tons of falling ceiling panels.

Since the accident, authorities have zeroed in on the bolt-and-epoxy system that failed to hold suspended ceiling panels in place where Milena Del Valle was killed. Inspections have revealed slippage in dozens of other tunnel locations, and workers have been reinforcing potentially weak connections.

The ramp expected to reopen represents only about 10 percent of the Big Dig tunnels and ramps that have been closed since Del Valle's death. Other tunnel sections closed after the accident could take months to inspect and reopen, Romney has said.

The Big Dig highway project buried a highway network that used to slice through the city, creating a series of tunnels to take traffic underground. Although it's been billed an engineering marvel, the most expensive highway project in U.S. history has also been plagued by leaks, falling debris, delays and other problems linked to faulty construction.

After the July 10 accident, Romney seized control of inspections, promising a "stem to stern" safety audit. He also forced out the head of the Massachusetts Turnpike Authority, which oversees the Big Dig.

State and federal criminal investigations are also under way to determine if construction failures resulted from criminal negligence.