Inspection reports show how zoo bridge gradually fell apart

Inspection reports on the soon-to-be dismantled zoo bridge paint a picture of a span that was literally falling apart.

Rust, split wooden beams, loose railings and twisted support columns are all laid bare in the inspection reports.

The span, which opened for horse-and-buggy traffic back in 1908, will be lifted off its moorings this week.

It's being replaced by a new bridge just to the west, which is currently under construction.

• 108-year-old Calgary Zoo bridge expected to be removed in one piece this week

Through a freedom of information request, CBC News obtained inspection reports for the zoo bridge.

Limit of two vehicles at a time

The most recent inspection report, submitted by ISL Engineering in January 2017, concluded that while the bridge could remain open for limited vehicle access to the zoo, traffic should be infrequent.

It recommended that no more than two vehicles be allowed on the bridge at the same time and that they stay20 to 25 metres apart.

The inspectors concluded that the sidewalk not be used by pedestrians. Instead, pedestrians walking to the zoo were to be diverted onto the roadway.

As well, ISL recommended the bridge be inspected every two weeks to monitor its condition.

A 2015 email from the city's manager of bridges to other officials noted that there is an ATCO gas line on the bridge, something that is not allowed.

One thing drivers won't miss about the bridge isits narrow lanes.

An inspection report notes that at just 2.55 metres wide, each lane on the bridge was narrower than the recommended minimum width of 2.7 metres.

Broken side mirrors were common on the bridge after vehicles side-swiped each other. As well, there are pictures in the inspection reports of several damaged sections on the bridge's guardrails and wooden support beams hit by vehicles.

Traffic restrictions on the zoo bridge started in 2016and were gradually tightened.

In March of this year, the bridge was closed to all public access.

City hoped bridge could last a bit longer

The city had hoped that the zoo bridge would last until its replacement was completed.

"That was the hope but you know, when they designed it back in 1908, I don't think that they really pinned down 2018 to be the date it lasted until," said Katherine Hikita, a structural engineer with the City of Calgary.

"We were just kind of wait and see and monitor, inspect to see how long it would last."

That being said, she said the inspection reports made it clear the bridge was deteriorating.

"It did elevate our level of concern about the condition of the bridge and help put together the business case for an early removal, which we're doing right now," said Hikita.

Large crane will help remove bridge

A crane that was brought in to help install steel girders on the new bridge will be used to lift the steel truss section of the old bridge from its perch above the Bow River.

The span will be placed on the zoo side of the river where it will be disassembled.

Hikita said some elements of the bridge will be incorporated into a public art display tobe installed near the new bridge.

If anything, the bridge lasted longer than anyone could have anticipated.

"I think 108 years is a good haul for any bridge," said Hikita.

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