Drivers got a little relief Wednesday from the traffic-ups created after a deadly ceiling collapse in Boston's Big Dig highway system: One ramp that had been closed for repairs reopened to the public.

The newly reopened ramp funnels drivers through the Ted Williams Tunnel toward Logan International Airport. It was closed after tons of concrete panels fell from the ceiling in a nearby connector tunnel July 10, crushing a motorist.

"This makes a huge difference," Gov. Mitt Romney said at a news conference before the midnight reopening. "Both directions, eastbound and westbound, will now be able to have cargo trucks going in both directions, automobiles can go both directions."

But Romney cautioned that plenty of work remains in other tunnels closed since the accident and problems continue to come up as engineers review the safety of the tunnel network.

The reopened ramp represents only about 10 percent of the total area of the Big Dig tunnels and ramps that have been shut down. Other sections could take months to inspect and reopen, Romney said.

The Federal Highway Administration and Office of Inspector General at the U.S. Department of Transportation said the decision to reopen was the result of a thorough inspection of tunnel repairs and "the state's implementation of an aggressive plan to monitor the reopened areas."

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

Romney said Tuesday that inspectors over the weekend also discovered that brackets used to connect the panels to the ceiling weren't big enough, and workers had to replace 23 brackets.

The $14.6 billion 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.

State and federal criminal investigations are also under way to determine if construction failures resulted from criminal negligence, and the system faces financial hurdles.

State Treasurer Timothy Cahill said the Big Dig budget has a $133 million deficit after a freeze in federal highway funds. The Federal Highway Administration froze $81 million last year, saying project managers needed to explain how they would fix tunnel leaks. The Turnpike Authority then spent another $52 million on the assumption it would get federal money that hasn't come, leaving the $133 million hole.

In a letter to Romney, Cahill said spending on the project could siphon funds from other public works projects, The Boston Globe reported. Cahill asked Romney to explain how the state will cover the project's cost, including repairs and a "stem to stern" review. Romney seized control of the review from the Turnpike Authority last month.

Romney spokesman Eric Fehrnstrom said if financing problems are found, Romney would disclose the problems and work to solve them.

With Wednesday's ramp reopening, traffic enters the Ted Williams Tunnel eastbound to the airport from a surface bypass road in South Boston. The eastbound tunnel had been open only to buses, while other traffic has been diverted to older routes.