A primer for the new Johnson Street Bridge

As of March 31, Victorians should be able to drive, walk or cycle across the new Johnson Street Bridge, Canada’s largest bridge of its type.

What is it? It’s a bascule bridge, which uses a counterweight (located either above or below the bridge deck) to balance the span when it lifts to allow marine traffic to pass. There are three types of bascule bridges — a fixed trunnion, rolling lift trunnion (sometimes called a Scherzer rolling lift) and Rall-type.

article continues below

The new bridge is similar to a rolling-lift type, but with significant differences. It operates a little like a Scherzer rolling-lift bridge, which rolls back onto a curved girder, with a motion like that of a rocking chair. On the Johnson Street Bridge, the rolling girder sits on support wheels, and a rack-and-pinion motor drives the bridge.

The bridge is part of a major corridor in and out of downtown Victoria; the existing bridge sees about 30,000 crossings made by motor vehicles, pedestrians and bicycles every day.

As crews work steadily to put together the components, officials at Victoria City Hall have said they are confident the new bridge will be open to traffic by March 31.

While residents look forward to the imminent completion, the road leading to the bridge has been a bumpy one.

History: It started eight years ago, when Victoria city council held a referendum on whether to replace the Johnson Street Bridge, which opened in 1924. A public debate ensued over the merits of building new versus rehabilitating the original bridge.

“There were those who wished to retain the old bridge based on its nostalgia value,” said Jonathan Huggett, the City of Victoria’s bridge project director. “With a renovation on a 90-year-old structure, you just don’t know what you will find until you take it apart. Also, it’s one thing to repair a structure and another to try to seismically upgrade it.”

The referendum asked citizens for approval to borrow funds to finance construction of a new bridge.

From the outset, there were those who didn’t see the logic of replacing the original structure.

“It may be old, but the bridge has functioned without any significant problems for 85 years,” said Ross Crockford, who advocated for keeping the old bridge. “I didn’t want it sentenced to death without a fair trial.”

In November 2010, the project was given the go-ahead after citizens voted 61 per cent in favour of a new bridge.

At that time, the bridge was set to be completed by September 2015 and the cost was pegged at $63 million.

The principal criticism over the years has been the escalating cost of construction. The biggest shock came in 2012, when the cost jumped to $92.8 million. But it didn’t stop there, with the estimate now at $105 million.

Critics say much of the additional cost and delay can be traced to the complexity of the design and the fact it has never been built on this scale anywhere else.

That’s unfair, Huggett said. “What you need to realize is that we now have a number of features we didn’t have before [on the old bridge],” he said.

“It can now withstand an earthquake. The channel under the new bridge is six metres wider, and it now accommodates bicycles.”

The escalation in cost doesn’t surprise Crockford. “There was no evaluation on the practical issues,” he said. “They picked it because it was a fancy design, without consideration on the risks involved with picking an unusual design. I believe the bridge costs $10 million just for the novelty design.”

Design: The original architect who conceived the concept was Sebastien Ricard of Wilkinson Eyre, an architectural company based in London, England. Although there have been significant changes over the years, the bridge still retains Ricard’s concept of the cradle support for the lift span — which allows the public to see the operating mechanism of the bridge.

In a typical design, there would be an axle running the width of the bridge. Transferring the mechanism to raise and lower the bridge to the two outer rings creates a “cradle” for the lift span to sit in and a void in between.“This is a very attractive piece of architecture, with very few examples to compare to it around the world,” Huggett said. “There is one similar to it in London, but it is much smaller.”

Designers spent significant effort on the visual aspects of the new bridge, settling on eye-catching rings (each steel ring is approximately 15 metres in diameter and weighs 290 tonnes) with exposed counterweights.

The new bridge is being promoted as functional and meeting current design standards, especially in regard to seismic integrity. It has a life expectancy of at least 100 years.

Huggett said people will likely warm to the new bridge once they get a chance to walk on it at the end of March. “I think people will like the feel and touch of the structure.”

Crockford is less impressed.

“They held a popularity contest. The design of the bridge, with all its welds, is closer to constructing an airframe. All that welding is labour intensive and few people realized just how difficult this is to put together.”

He said that because of all the labour involved, the manufacturing of the steel had to be sourced overseas to keep costs down.

Steel controversy: Having an offshore firm manufacture the major components saved money, but it came with risks. The project was rocked by news that the first batch of steel had been rejected when it was found to be below designer specifications.

The pieces were fabricated in China by the Zhongtai Steel Structure. The company remanufacture the components, under the watchful eye of monitors hired by the City of Victoria. While the faulty work did not add to the costs, it set back the date of completion from September 2015 to the end of December 2017.

A further delay in fabrication eventually pushed the completion date to March 31, 2018, where it now stands.

Bicycles: Huggett points out that the old bridge isn’t very bicycle-friendly. In contrast, the new bridge dedicates half of its surface to pedestrians and bicycles. It has two dedicated on-road bike lanes in addition to a multi-purpose walkway on the north and a pedestrian walkway on the south side of the bridge.

Despite the bike lanes, the number of lanes for motor vehicle traffic remains the same, at three.

Most cyclists will welcome the change of materials on the bridge deck. The existing bridge has an open-grate surface; the new one has solid steel covered with an epoxy-like material. The texture of the material is smoother on the bicycle lanes than the surface used by vehicles.

Pedestrians can travel from one side to the other either on a walkway (on the south side of the structure) constructed from aluminum planks imported from Germany or along a multi-purpose walkway on the north side of the bridge.

Lower maintenance: Once it is up, the new structure is expected to require less maintenance than the old bridge.

Designers have gone from using an electric motor to a more efficient hydraulic system to raise and lower the bridge.

Crews won’t have to repaint the structure as often. Due to advances in paint, the next time the bridge will need a new coat of paint is estimated to be in 20 years, despite being in a marine environment with surfaces constantly exposed to salt spray.

“You can’t pop the champagne just yet,” cautions Crockford. “We’re not out of the woods yet. The next mystery is how long it will operate without problems. The City of Victoria’s project director calls it a Swiss watch. Given all sorts of things that have been missed over the last few years, it is a pattern that worries me. Ask me again in 20 years’ time.”

Upcoming: Once the new bridge is in place, work will continue on fenders, meant to protect the bridge if a vessel hits it.

After the new bridge is opened, crews will take three months to disassemble the old bridge, after which the land on both shores leading up to the old bridge will be rehabilitated, with plazas planned.

Upcoming key milestones include:

1. The installation of the rings and lower counterweight at the end of November, with the exact date dependent on availability of the Dynamic Beast crane.

2. Installation of the main bascule span in January.

3. Commissioning and testing of the new bridge in February and March.

Read Related Topics

© Copyright Times Colonist

Most Popular

Find out what's happening in your community.