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New bridge takes shape over Victoria harbour

0 527 Infrastructure

BY SHANNON MONEO - A downtown Victoria construction project looms large in a couple of ways.
New bridge takes shape over Victoria harbour
Photo: Shannon Moneo

 

The new Johnson Street Bridge, to replace the existing 1924 bridge, will be one of Canada's largest single-leaf bascule bridges.

The three-year project, which started in spring 2013, is the City of Victoria's largest infrastructure project to date with a total price tag of $92.8 million.

Of that, $63.2 million goes to PCL Constructors Westcoast, which bested two other competitors to build the bridge that will span Victoria's Inner Harbour.

"It's a very unique project, building a lifting bridge," said Dwayne Kalynchuk, the City of Victoria's director of engineering and public works.

While the new three-lane bridge with bike lanes and pedestrian walkways is being built, the existing bridge, immediately to the south, will remain open.

PCL's construction manager for the project said fine-tuned logistics are crucial.

Building around an active waterway, near a bridge, which lifts three to four times a day and has 30,000 vehicle, pedestrian and cyclist crossings daily, takes a lot of organizing said Dan Leachman.

"Working over water is challenging and working near a moving bridge is even more challenging," said Leachman, who came from PCL's Seattle office to work on the project, the first time PCL has had its Canada-U.S. staff work jointly on a project.

"It's like two different jobsites," said the veteran of 15 major bridge projects.

From May to October 2013, crews began site-clearing, soil-grading and built work areas.

A further complication, Leachman said, has been moving excavated soil, including contaminated material.

A stockpile sits at the site.

But, work has been progressing well, Kalynchuk said.

All 16 steel-cased drilled shafts for the bascule pier – the housing to support the mechanical and electrical system which supports and allows movement of the bascule leaf – have been installed.

Instead of using the typical cofferdam, PCL is building part of the shell above the water line.

The box will be lowered about five metres, concrete will be poured to seal it and water will be pumped out before the base mat and walls are poured, Leachman said.

In July, there were questions whether the existing bridge should be closed to speed construction, but closing the Blue Bridge would have a negligible effect on the pace of construction, Leachman said.

Work has taken place on a Monday to Friday, 7 a.m. to 4:30 p.m. schedule and Leachman didn't see the need to extend those hours.

To reduce capital and maintenance costs and accelerate construction, PCL suggested engineering modifications, which were adopted.

They included reducing the size of the bascule pier, simplified geometry for the rest pier, simplified truss sections, concrete approach spans rather than steel and the use of a hydraulic mechanical system.

Progress has been timed to coincide with the arrival of the bascule components being built by ZTSS Bridge near Shanghai, China, at a cost of roughly $11 million.

The two large wheels and large truss – the bascule leaf – are due to arrive in July 2015, Kalynchuk said.

Following that, traffic will grind to a halt on the old bridge for two, five-day periods, Leachman said.

The first five-day closure will be to install the large wheel assemblies.

To do that, the massive Arctic Tuk crane barge, which fills the whole channel near the bridge, will put its Manitowoc 4600 Ringer crane to work.

As Leachman explained, two big rings and the counterweight box sit inside the bascule pier supported by four equalizer wheel assemblies.

The truss and roadway deck that span the waterway are connected to the large rings and are counterbalanced by lead weight on the shore-side of the rings.

The balanced condition of the bridge makes the mechanical effort to lift the bridge small, as the rings rotate on the equalizer supports.

The second five-day closure will happen not long after to install the truss span.

Following that, an intense testing of the bridge's components will occur.

It's not known how long the piece-by-piece commissioning plan could take.

"There are cycles we have to run through. It could take months. It depends how much trouble-shooting we have to do," Leachman said.

The city forecast the bridge opening in fall 2015.

PCL is also responsible for realigning road approaches at both ends of the bridge, building a retaining wall, creating new public areas and walkways and decommissioning the old bridge, which will involve removal of the superstructure for recycling.

That should be finished by early 2016.

Earlier this year, PCL asked the city for an additional $7.9 million in funding above the fixed contract figure of $63.2 million, as well as an extra 5.5 months to complete the project.

The need for more money and time were reportedly due to a delay in receiving design plans.

While Victoria Mayor Dean Fortin has said he expects the project to be on-time and on-budget, Leachman said that "sensitive negotiations" are taking place.

He also said that PCL is, "dedicated to delivering the job irregardless of what happens."

Once all the bridge bugs are eliminated, the new light grey structure will be drenched in blue LED lights come nightfall, a nod to its Blue Bridge predecessor.

A sizeable contingent of southern Vancouver Island sub-contractors and suppliers are working on the project.

by Shannon Moneo

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