Big Dig completion date pushed back

Substantial completion of the Big Dig, which had been scheduled for tomorrow, has been moved back to Halloween, and all roadwork connected with the project won't be finished until May 31, project officials said yesterday.

Construction crews are furiously working to wrap up the $14.6 billion project, started in 1991. Though the Interstate 90 and Interstate 93 tunnels are open to traffic, as are most entrances and exits, there remain about a dozen ramps and road segments unfinished.

The project is now scheduled to reach substantial completion -- which officials define as when 60 major pieces are done -- by Oct. 31, said Mariellen Burns, spokeswoman for the Massachusetts Turnpike Authority.

In a statement e-mailed to the Globe, Burns said the delay ''will have no impact on motorists or the overall price tag of the project."

''We continue to move ahead with major accomplishments: We opened the Summer Street off-ramp from southbound I-93 this past Saturday, will open the HOV lane from the South Station bus terminal to Logan airport and to southbound I-93 this week, and the permanent alignment from the Callahan Tunnel to Route 1A will open within the next week."

At a ramp opening ceremony last month, Turnpike Authority chairman Matthew J. Amorello said surface restoration might continue into spring. In 2003, project officials had set this month as the goal for project completion, though they said in June that overnight work to patch hundreds of leaks in the tunnels would continue until at least January.

Yesterday afternoon, at a meeting of the Central Artery Environmental Oversight Committee, project officials displayed a map showing unfinished areas of the Big Dig with the scheduled completion dates. The map was the first to include a 2006 date for completion of road paving. Final configuration of a portion of Atlantic Avenue and Summer, Congress, Pearl, and Oliver streets was marked as being done by May 31.

''We have a couple of major construction issues we are dealing with that are driving the schedule here," Richard Lynt, area construction manager, told about 40 people.

Lynt said deficiencies with a recently built underground steam line, plus problems with an electrical substation, have delayed work along Atlantic Avenue above the I-93 tunnels. With work below ground continuing, crews will not be able to pave the streets in their permanent alignment before winter starts, he said, pushing the final construction into spring.

Lucas Wall can be reached at lwall@globe.com.