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Rail Safety Advisory Letter 01/22

25 January 2022

Director General, Rail Safety
Transport Canada
14th floor, Enterprise Building
427 Laurier Avenue West
Ottawa ON K1A 0N5

Subject :

TSB Rail Safety Advisory Letter 01/22 (TSB occurrence R21H0114)
Conflicting authority to enter main track without obtaining a train location report

On 02 September 2021, at about 1025,Footnote 1 Canadian National Railway (CN) train Z14921-02 (Z149), equipped with 2 head-end locomotives hauling 202 intermodal car bodies loaded with double-stacked containers (length: 12 359 feet, weight: 14 688 tons), was proceeding westward at approximately 42 mph on a clear signal on the north main track of the Kingston Subdivision near Prescott, Ontario. The operating crew of Z149 consisted of a locomotive engineer and a conductor.

Train movements in the area are governed by the centralized traffic control (CTC) system as authorized by the Canadian Rail Operating Rules (CROR), dispatched by a CN rail traffic controller (RTC) located in Edmonton, Alberta. The track in the vicinity of the collision consists of double main track. It is Class 5 track according to the Transport Canada (TC)–approved Rules Respecting Track Safety, otherwise known as the Track Safety Rules (TSR). An average of 18 CN freight trains and 12 VIA Rail passenger trains operate in the area each day, making it one of the busiest rail corridors in Canada.

As Z149 was approaching Prescott, local CN road switching assignment L53231-02 (L532), operated by a locomotive engineer, a conductor, and an assistant conductor, had just completed switching at industrial spur tracks KE-07 and KE-08. L532 had just returned to spur track KE-01, which was adjacent to the north main track of the Kingston Subdivision and within the town of Prescott. L532 now consisted of only 2 locomotives: CN 4799 and IC 9629. In preparation for the return trip to Brockville, the crew of L532 was operating from CN 4799, which was oriented with the locomotive cab facing westward, and the cab of the trailing locomotive (IC 9629) was facing eastward.

Unknown to the crew of Z149, a CN RTC had issued the crew of L532 a Rule 568 authority.Footnote 2 The authority permitted L532 to enter the main track at the hand-operated switch located at Mile 113.36 on the north main track of the Kingston Subdivision and proceed westward to Brockville.

While in the cab of locomotive CN 4799 (facing westward), the assistant conductor and locomotive engineer of L532 copied and completed the written Rule 568 authority. The conductor of L532 was positioned on the ground near the KE-01 crossover switch and listened to the transmission of the authority on his handheld radio. Once the authority was completed, the conductor then proceeded to line the hand-operated crossover switch from track KE-01 onto the north main track.

After the switch was lined, the assistant conductor of L532 looked in the locomotive side mirror and noticed that Z149 was approaching from the east on the north track of the Kingston Subdivision. Realizing that a collision was imminent, the crew of L532 attempted to warn the crew of Z149 by radio to put the train in emergency because the main-track switch was lined into KE-01. The assistant conductor then exited the cab in an attempt to reach a safe location, while the locomotive engineer remained in the cab of CN 4799.

As Z149 approached Mile 113.36, the crew observed that a switch target was red, which indicated that the hand-operated main-track switch was lined against them and into an adjacent spur track located to the north. At 1027, the locomotive engineer placed the train into emergency when the head-end was approximately 970 feet east of the switch. Z149 then entered the spur track and collided head-on with the eastward-facing locomotive (IC 9629) of L532 at 37 mph (Figure 1).

Figure 1. Aerial views of the accident site (Source of main image and inset image: Ontario Provincial Police, with TSB annotations)
Aerial views of the accident site (Source of main image and inset image: Ontario Provincial Police, with TSB annotations)

Following the collision, all 3 crew members of L532 were transported to a hospital in Ottawa, Ontario. The conductor and assistant conductor were treated and released, while the locomotive engineer was seriously injured. Neither of the crew members of Z149 were injured during the collision.

Site examination revealed that the locomotives on both Z149 and L532 derailed and were extensively damaged. In addition to the locomotives, 14 intermodal car bodies on Z149 that were loaded with double-stacked containers derailed, coming to rest in various positions throughout the derailment area and blocking both the north and south main tracks of the Kingston Subdivision (Figure 2).

Figure 2. Aerial view of the occurrence site, looking east (Source: Ontario Provincial Police)
Aerial view of the occurrence site, looking east (Source: Ontario Provincial Police)

Both locomotives on L532 (CN 4799 and IC 9629) came to rest on their sides north of the spur track. The fuel tank of IC 9629 was punctured and released an undetermined amount of diesel fuel. The force of the collision propelled the 2 locomotives on L532 westward toward 9 cars that were stationary on the spur track. The locomotives then collided with the cars, derailing and damaging 2 empty covered hopper cars.

One of the intermodal cars on Z149 and the containers stowed on it came to rest mere feet from a natural gas pipeline adjacent to the track, near a residential area (Figure 3).

Figure 3. Derailed equipment within feet of a natural gas pipeline adjacent to the track (Source: TSB)
Derailed equipment within feet of a natural gas pipeline adjacent to the track (Source: TSB)

The derailment displaced or destroyed about 1000 feet of track on both the north and south main tracks of the Kingston Subdivision as well as the KE-01 spur track between Mile 113.36 and Mile 113.55. No mechanical or track defects were observed during the site examination.

To date, the investigation has identified that when the CN RTC issued the CROR Rule 568 authority to the L532 operating crew, the RTC did not properly apply item 3018 – Rule 568 (c) of the CN RTC Manual.Footnote 3

Both CN and Canadian Pacific Railway (CP) have software that RTCs use to manage rail traffic on their systems, which includes issuing CROR Rule 568 authorities. The software provides a prompt to an RTC when there is a train lined in, or operating within, the same CTC block as the requested authority. If an RTC enters signal blocking before issuing a CROR Rule 568 authority for a 2nd train to enter the main track, a prompt appears on the RTC monitor. The RTC is expected to obtain a location report from the train crew that is operating within the block. The RTC then enters that train location in the system to ensure that the train occupying the block on the main track has passed the location where the 2nd train requesting the CROR Rule 568 authority intends to enter the main track.

However, it is possible for an RTC to override the prompt and issue the CROR Rule 568 authority to the 2nd train without obtaining a train location report from the train occupying the block. When the prompt is overridden, the software will generate a completed CROR Rule 568 authority, thus permitting the 2nd train to enter the main track before the 1st train has passed by that location. This appears to have been the case in this instance.

The CN RTC system does not allow a prompt to be overridden in other CROR track occupancy situations. For example, when a CN track foreman asks to enter the main track on a follow-up electronic track occupancy permit or when a regular track occupancy permit is required, current CN software prevents a prompt override. In such cases, the train location report is a mandatory data field: it must be filled in before the system will generate the authority. If this field is not filled in, then the software system automatically rejects the authority request.

From 2018 to 2020 there were 4 other occurrencesFootnote 4 where CN system prompts were overridden by RTCs and CROR Rule 568 authorities were issued in error. While a system prompt before issuing a CROR Rule 568 authority is administrative in nature, it is a safety-critical task that is necessary to protect against the risk of a train collision.

As this occurrence demonstrates, significant train accidents can occur when a system prompt for compliance with a safety-critical task under the CROR can be overridden without the benefit of any secondary oversight or a physical defence. Therefore, Transport Canada may wish to review the railway RTC systems software prompts of all safety-critical tasks, including the issuing of CROR Rule 568 authorities, that can be overridden when equipment is already in the block, and confirm that there are adequate layers of defence to protect against unsafe RTC decisions.

The TSB would appreciate being advised of any action that is taken in this regard.

Upon completion of investigation R21H0114, the Board will release its investigation report into this occurrence.

Yours sincerely,

Original signed by

Paul Treboutat
Director, Investigations (Rail/Pipeline)
Transportation Safety Board of Canada