Backgrounder (R21V0143)

Common causes of fire in Canada's rail transportation sector^{Footnote 1}

How can a train cause a fire on a railway right-of-way?

• Locomotive exhaust stack fires can occur when diesel fuel is not burned properly or the stack and spark arresters are not cleaned periodically. In such cases, sparks may come out of the stack and could drift into flammable material on the right-of-way or beyond the right-of-way.^{Footnote 2}
• Normal train braking does not cause fires. However, train braking can produce sparks, particularly in situations where a brake shoe is worn down to the backing plate resulting in the steel backing plate contacting the steel wheel tread. It should be noted that brake shoes are typically replaced prior to being worn down to the backing plate. Downhill braking or emergency brake situations may generate high temperatures in railway wheels. 
• Roller bearings on rail car axles may occasionally fail or burn off, which can cause a derailment and possibly a fire. To prevent this, bearing temperatures are monitored on all principal main tracks by wayside detector systems. This permits identification, removal and repair of cars with hot bearings prior to failure.
• Fires within rail cars are occasionally reported when flammable cargo, such as sulphur or lumber, have been ignited. Ignition of such fires can be caused by spontaneous chemical processes or exposure to an external source.
  
• Traction motor fire: Traction motors are the electric motors that drive the wheels on a locomotive. They are affixed to the axles underneath the locomotive. Traction motors may occasionally overheat and catch fire. The high voltage cable supplying power to the motor can on occasion sustain damage and potentially cause a fire as well.

Fires related to track maintenance activities

• Rail repairs: The repairing of broken rails requires continuous welded rails to be cut using large saws that produce sparks. The rails are cut on either side of the break and replacement plug rails are installed. The rail joints from the plug are removed by welding the rails into place, which also causes sparks. To mitigate the risk of a fire, all repair activities are monitored closely and conducted with fire suppression equipment available.
• Rail grinding: Rail grinders restore the rail surface profile. Rail grinders are large on-track machines equipped with multiple grinding stones. Grinding off rail surface defects to restore the optimum rail profile produces sparks. Rail grinders operating in dry conditions are followed by hi-rail water trucks to monitor and extinguish any resulting fires.
• Rail ties: Rail ties and bridge timbers are treated with creosote to protect against decay and insect damage. Creosote, an oily by-product of the distillation of coal tar, is flammable. Stockpiles of new and used ties present readily available fuel for intentional or accidental fires.
• Combustible material such as used ties or brush that is not cleaned from the right-of-way may provide fuel for a fire.