Macdonald Bridge Big Lift start planned for this weekend

Halifax Harbour Bridges will decide Friday whether it's ready to begin the $150million "Big Lift" on the Macdonald Bridge this weekend already a few weeks later than originally forecast.

"We are optimistic we are going to replace it, but safety is going to rule here. We are either ready to go 100 per cent or we delay," says project lead Jon Eppell.

• The Big Lift, explained

If the install goes ahead, the span will be closed for the weekend.

A yellow gantry is in place on the Macdonald Bridge, ready to lower and lift the first of 46 deck sections as the Macdonald becomes only the second suspension bridge to replace decking while remaining open for traffic.

"That's what makes this project so complicated. We're replacing such a significant amount of the bridge at atime and making it safe for the public to drive on it at the same time," say Eppell.

The first segment,a 120 tonne new steel deck known as D-1,is waiting at Cherubini Metal Works in Woodside. A barge will float it down Halifax Harbour for the first installation.

The challenge will be fitting the new deck into the existing structure. That has meant installing a new temporary deck connection to ensure the span has enough strength to support traffic. There is also a wind limit of 36 kilometres per hour.

Traffic impact

The Macdonald Bridge will be closed for the first four weekends during initial section replacements.

Provided contractor American Bridge can replace a section in 10.5 hours, most of the work will be done at night. Thebridge will closefrom 7 p.m. to 5:30 a.m..

Other weekend closures will be needed to replace mid-span sections, those near the main green towers and some over DND property on the Halifax side.

This kind of suspension bridge deck replacement has only happened once before at the Lions Gate bridge in Vancouver.

Halifax Harbour Bridges missed its original Aug.28 deadline to remove the first section. Eppell says the real test will be if all the sections are replaced on schedule over the next 12 months and within budget.

"That's really what we should be measuring against, as opposed to when does the first one happen. The first one isn't going to happen until we are prepared and safe to do so," he says.

A detailed planning meeting was held Tuesday but the final decision will be made on Friday, he said.