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Crews demolishing rail bridge damaged in flood

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by Richard Gilbert last update:Sep 22, 2014

Canadian Pacific Railway is demolishing a rail bridge in Calgary, Alberta, after the structure failed due to flooding and caused the derailment of a train transporting dangerous goods over the Bow River.
Flooding in Calgary, Alberta caused the structural failure of the Bonnybrook Bridge.
Flooding in Calgary, Alberta caused the structural failure of the Bonnybrook Bridge. - Photo: City of Calgary

“CP (Canadian Pacific) crews have begun the process of dismantling the bridge,” said company spokesperson Ed Greenberg.

“As part of the operation, two securely positioned cranes are being used to carefully remove impacted spans and other bridge material. The process is expected to take about two-three weeks.”

A Canadian Pacific train pulling 102 cars was forced to park on the Bonnybrook Bridge, when the span suddenly started to sag as the train crossed the river early on June 27.

Calgary police, fire department and Emergency Medical Services found six rail cars on the damaged bridge.

One of the cars was empty, but the other five contained petroleum distillate.

All the cars remained upright and didn’t leak.

Calgary Emergency Management Agency said the bridge had dropped at least 0.6 metres (two feet) in an hour and a half.

There are two rail bridges over the river, which are about 7.5 metres above the water.

“In our preliminary investigation, it was determined that despite numerous inspections of the bridge, one of the four piers, which supported it, experienced scouring from the increased flows of the river due to flooding,” said Greenberg.

“This scouring occurred at the very bottom of the pier structure. This then caused the bridge to sag in the location of the scoured pier, leading to the derailment on the bridge.”

Emergency responders immediately set up a half mile evacuation zone around the rail bridge.

They also closed several major roads as a precautionary measure.

Next, they began a tense rescue operation by disconnecting and moving rail cars from the train at the north and south end of the bridge.

The six derailed cars were anchored in place by coupling them to another train of cars filled with grain and rock.

Each of the six cars was tethered together and to the anchoring train.

Vacuum trucks were used to transfer the petroleum distillate from the cars on the damaged bridge to rail cars on the adjacent undamaged bridge.

Petroleum distillate is a non-regulated commodity that is used as a diluent for heavy oil.

This product is also used as a solvent in metal polishes, paint thinner, wood stain and paint.

For this reason, fire officials also worked with nearby companies to identify areas where a boom could be built downstream, just in case the cars fell into the river.

Greenberg said that by 10:30 p.m. on June 27 all the product from the five cars had been carefully transferred to rail cars that were brought in. The rail cars were safely removed from the damaged structure at about 2 a.m. on June 28th.

The Transportation Safety Board (TSB) deployed a team to the site of the train derailment, which is just east of CP’s Alyth Yard

“We are still gathering information and waiting for the results of a survey of the bridge and underlying structure,” said John Cottreau, manager of media relations with the TSB

“That’s where the investigation is right now. They are currently investigating the occurrence and producing a report.”

Cottreau said Canadian Pacific Rail is cooperating with the TSB as it investigates the incident and helping to gather as much information as possible.

The TSB deployed a two-person team, which included investigators who specialize in the operation of trains and railway infrastructure.

The team spent four days on site investigating the incident

“They will take the time they need to do a thorough job, which could take up to a year,” said Cottreau.

“It is a class three investigation, which means there will be a written report at the end of it all.”

The TSB is an independent agency that advances transportation safety by investigating marine, pipeline, rail, and aviation occurrences, and communicating risks in the transportation system.

The board investigates an occurrence when there is a high probability that it can advance transportation safety and reduce risks to persons, property or the environment.

According to Greenberg, the bridge was inspected 18 times since June 20, when the flooding began in Calgary, until the morning of the incident.

last update:Sep 22, 2014

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