The Macdonald Bridge has reopened in time for Friday's evening rush hour, almost nine hours later than expected.

The gates reopened at about 2:15 p.m.

Halifax Harbour Bridges says the contractor, American Bridge Company, will not be permitted to close the bridge again until it can ensure there will be no delayed openings.

Steve Snider, the CEO of Halifax Harbour Bridges, said that means the bridge will remain open on Friday night and 24/7 over the weekend — until at least Tuesday night.

He says the bridge commission hopes to have a plan from the contractor soon.

"We are not planning on 40 weeks of doom," Snider told CBC's Maritime Noon. "They can use their experience from last night's work to help them refine their approach to doing the work. They can take a look at other ways of doing it."

Many drivers said the closure doubled the length of their commute and caused delays.

2.5 cm of clearance

Snider said crews had trouble getting the lifting gantry into place. It's the large yellow structure being used to lift the new bridge segments into place. It needed to move 20 metres along the span to prepare to lift the next segment.

Steve Snider, the CEO of Halifax Harbour Bridges, said the contractor will not be permitted to close the bridge again until it can ensure there will be no delayed openings. (CBC)

"This is a piece of work or exercise that once you start, you're committed to completing it," he said Friday afternoon before the bridge opened.

"They've encountered some difficulties, but we've been advised that hopefully within the next couple of hours they should have it in place and hopefully it will be out of the way."

He said part of the problem was moving the dollies underneath the gantry because there is only about 2.5 cm of clearance.

He said crews had to re-level the gantry every time it hit a bump. Reattaching the gantry with pins posed additional challenges because of wind conditions, he said.

This is the first time the gantry has had to be moved during the project.

'We're very, very sorry this is occurring'

This kind of suspension bridge deck replacement has only happened once before — at the Lions Gate Bridge in Vancouver. Snider said the gantry being used on the Macdonald Bridge is different than the one used in that project.

"We're very, very sorry this is occurring," said Snider.

The bridge had been closed nightly between 7 p.m. and 5:30 a.m. as part of ongoing work for the Big Lift project to replace the decking on the bridge.

Snider said the contractor has already factored winter weather into the work schedule and they're anticipating there will be nights when it's not possible to work due to poor weather.

The first deck segment associated with the Big Lift was lifted into place last weekend. However, contractors ran into delays and the bridge remained closed during Monday's busy morning commute for several hours.

The project, which has more than 40 weeks to go before it's finished, is expected to extend the life of the bridge by 70 years or more.