On the evening of 17 June 2016, a two-member crew employed by the Canadian National Railway (CN) was performing switching operations using a remote control locomotive system in MacMillan Yard. The crew had assembled a 9000-ton, 4500-foot-long assignment, consisting of 74 cars and 2 locomotives. As the switching operations required extra room, the crew received permission to move the cut of cars south along a slightly ascending grade toward the edge of MacMillan Yard and then downhill onto the main track of the York Subdivision. When the crew attempted to stop and reverse the cars back into the yard, they continued to move and rolled uncontrolled for about 3 miles, reaching nearly 30 mph before an ascending grade brought them to a stop. The foreman's quick emergency call to the rail traffic controller asking for assistance to protect the uncontrolled movement minimized the risk of collision and of a more serious outcome.
The investigation found that the crew had not charged air brakes on any of the freight cars, which left only the independent brakes on the two locomotives to control the movement. The crew members were qualified train conductors, but did not have sufficient operational experience to safely perform the tasks in this section of the yard. They had requested and received advance job briefings during which they reviewed operational requirements. However the briefings, job aid and procedures did not provide them with sufficient guidance. The crew was aware of the assignment's length and weight, but did not fully understand how these factors affected train handling on a descending slope using only the locomotives' independent brakes. As conductors, they had received little training in locomotive operation and train handling, as this was not required under existing regulations.
"Since the Railway Employee Qualification Standards Regulations came into force in 1987, the rail industry has changed tremendously and the technology has evolved, but qualification standards and training requirements have not," said Board member Faye Ackermans. "Consequently, railway employees in safety-critical positions may not be sufficiently trained or experienced to perform their duties safely."
Uncontrolled movements of railway cars are low frequency–high-risk events that can occur due to insufficient securement, switching without air, or loss of control as was the case in this occurrence. While most occur in rail yards, uncontrolled movements that affect the main track present the greatest risk of adverse outcomes, particularly if dangerous goods are involved. The number of occurrences involving uncontrolled movements has increased by about 10% in the past five years, compared to the 10-year average.
Following the incident, CN conducted a risk assessment that included a review of topography and air brake use in all its switching yards in Canada. Based on the review, CN implemented new minimum braking requirements for each yard including how many cars require charged air brakes prior to accessing main track.