The layoffs of 500 track maintenance workers this week at Canadian Pacific Railway will raise the risk of future derailments and potential disasters, the union representing the workers warns.

The Teamsters Canada Rail Conference, maintenance division, is also denouncing CP for failing to do a formal risk assessment of how the job cuts could affect safety along railway lines across Canada — a requirement introduced after the deadly Lac-Mégantic train disaster in 2013.

Gary Doherty, president of the Teamsters Canada Rail Conference maintenance division, says the upcoming layoffs of track workers could raise the risk of future train derailments. (CBC News) "I don't think it's scaremongering at all," division president Gary Doherty told CBC News. "I think the public should be aware of the potential. My concern is derailments; [if] we don't have people out there properly maintaining the track or doing inspections, the potential for disaster is there."

Notices were issued earlier this month, with the Canada-wide layoffs coming into effect Thursday.

In a detailed statement, Canadian Pacific counters it has invested heavily in track infrastructure for years and that this week's layoffs are temporary until business picks up again.

"For the last 10 years in a row, CP has been the safest Class 1 railroad in North America, measured by train-accident frequency," Martin Cej, the railway's assistant vice-president of public affairs, said in a statement emailed to CBC.

"The recently announced temporary layoffs are the result of lower car volumes and softening demand in a lacklustre North American economy — factors that are affecting all railroads, not just CP," he wrote.

Derailments, faulty tracks

Concern about track maintenance and inspections has mounted recently after the Transportation Safety Board (TSB) investigated three major derailments last year along CN's lines through northern Ontario.

The TSB issued a rail safety advisory to Transport Canada, calling on the regulator to pay closer attention and to review CN Rail's "risk assessments" for the northern railway line.

TSB investigators concluded track failures contributed to the string of crashes — all within the space of a month — near Gogama, Ont., including one March 7, 2015 incident in which 39 rail cars derailed, caught fire and spilled crude oil into the Makami River. Investigators found worn rail at that site, which the TSB determined likely contributed to the crash.

An aerial view of a CN train derailment site near Gogama, Ont., following the March 7, 2015 incident. (Transportation Safety Board)

The TSB has investigated 13 major derailments in the past decade where investigators concluded track failures, poor maintenance and failures in oversight by Transport Canada were the primary cause.

Derailments attributed to track failure: TSB (Rail line / Location / Date) CN, Gogama , Ont., March 7, 2015

, Ont., March 7, 2015 CN, Gogama , Ont., March 5, 2015

, Ont., March 5, 2015 CN, Gogama , Ont., Feb. 14, 2015

, Ont., Feb. 14, 2015 CP, Banff, Alta ., Dec. 26, 2014

., Dec. 26, 2014 CN, Faust, Alta ., June 14, 2014

., June 14, 2014 CN, Fort Frances, Ont., May 23, 2014

CN, Gainford , Alta ., Oct. 19, 2013

, ., Oct. 19, 2013 CP, Provost, Alta ., April 28, 2013

., April 28, 2013 CN, Waterfall, Ont., July 14, 2011

CN, Brampton , Ont., Oct. 30, 2007

, Ont., Oct. 30, 2007 CN, Huntingdon , Que., March 29, 2007

, Que., March 29, 2007 CN, Mimico , Ont., July 14, 2006

, Ont., July 14, 2006 CN, South Parry, Ont., June 6, 2006

Only two of those derailments involved Canadian Pacific.

CP says it has "increased spending on infrastructure" in recent years "installing new track, new ties, new ballast and doing other work to ensure a safer railroad. … In addition, more than 700 switches have been removed from active service since 2012, a measure that significantly lessens the risk of incidents across the network."

Cuts pose 'no risk,' CP says

Canada adopted tougher regulations following the Lac-Mégantic disaster, requiring rail companies to conduct risk assessments of any major changes to operations or staffing that "may affect the safety of the public or personnel or the protection of property or the environment."

However, CP doesn't believe those regulations apply to these latest job cuts.

"CP carefully considered the changes that were being made and concluded that since they posed no additional risk to employees, the public, property or the environment, a risk assessment was not required. Transport Canada was notified and agreed with this conclusion," the company said in its statement.

Transport Canada initially sidestepped inquiries from CBC, replying that questions on "whether CP has conducted a risk assessment should be addressed to the company." But the regulator issued another statement late Friday confirming it was fully aware that no risk assessment has been done.

"Following a review of the information received from CP regarding the temporary layoffs, Transport Canada determined that the company is not in violation of the regulations," wrote spokesperson Roxane Marchand. "As the situation remains fluid, Transport Canada will continue to engage with CP on developments."

Officials have yet to explain why the post-Lac-Mégantic regulations do not apply to CP in this case or who at Transport Canada made the decision.

Critics of Canada's current rail regulatory framework say they worry Transport Canada is failing to keep close watch over rail companies.

Mark Winfield, a government regulation expert and professor at York University, suggests Transport Canada needs to be "much more aggressive" in its oversight of railways. (CBC News) "It suggests that the world hasn't changed yet," said Mark Winfield, a government regulation expert at York University. "Despite Lac-Mégantic, despite the reports from the auditor general [and the] Transportation Safety Board … the institutional culture of Transport Canada, as a regulator, hasn't changed."

Winfield suggests Transport Canada needs to be "much more aggressive" in its oversight of railways. "And it needs to be much more transparent in how it does that."

Bruce Campbell, a University of Ottawa researcher and former executive director of the Canadian Centre for Policy Alternatives, called the government's handling of these recent CP layoffs troubling in light of the Lac-Mégantic findings that identified a lack of "adequate regulatory oversight" as one of the contributing factors.

"Transport Canada had better get its act together," said Campbell, suggesting the regulator doesn't have a "great reputation" right now.

"We've seen main track derailments — and in some cases major accidents with oil trains — since Lac-Mégantic," he added.

"The third anniversary [of the rail disaster] is going to be in a couple of weeks. I just hope the public doesn't get lulled into forgetting that lesson of Lac-Mégantic — the consequences of regulatory failure."