Rail Safety Advisory 617-04/19

Prevention of uncontrolled train movements for trains stopped in emergency on grades of less than 1.8%

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4th Floor
200 Promenade du Portage
Gatineau, Quebec
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11 April 2019

617-04-19
R19C0015

Ms. Brigitte Diogo (ASR)
Director General, Rail Safety
Transport Canada
14th Floor, Enterprise Building
427 Laurier Avenue
Ottawa, Ontario
K1A 0N5

RE:

Rail Safety Advisory Letter 617 04/19
Prevention of uncontrolled train movements for trains stopped in emergency on grades of less than 1.8%

Dear Ms. Diogo:

On 4 February 2019, at approximately 2148 Mountain Standard Time, Canadian Pacific Railway (CP) loaded unit grain train 301-349, proceeding westward to Vancouver, British Columbia (BC), was brought to a stop at Partridge, BC (Mile 128.7), on the Laggan Subdivision, using an emergency brake application. The track grade at this location was about 2.2%. Subsequent to stopping, the crew performed the required job briefing with a supervisor and the decision was made to set retainer valves to the high-pressure position on 75% of the cars on the train (84 cars). No hand brakes were applied. After an extended period of about 2 hours 45 minutes, a relief crew arrived to replace the crew at Partridge, whose maximum hours of service had been reached. About 10 minutes later, the train began to move on its own. The relief crew had not yet recovered the air brake pressure from the emergency brake application. The crew members were in the process of securing the train to facilitate the safe release and recharge of the air brakes. The train gradually accelerated to a speed in excess of the maximum track speed, and then derailed. A total of 99 cars and 2 locomotives derailed between the Upper Spiral Tunnel and Lower Spiral Tunnel near Field, BC. The crew members on board, consisting of a locomotive engineer, a conductor and a conductor trainee, were fatally injured. At the time of the occurrence, the temperature was −28°C. (TSB Occurrence No. R19C0015)

Following the occurrence, on 8 February 2019, Transport Canada (TC) issued Ministerial Order MO 19-03 (Annex A) requiring that trains stopped by an emergency brake application on a grade of 1.8% or greater (i.e., mountain grade) immediately apply a sufficient number of hand brakes before recharging the air brake system.

The leakage of pressurized air is always present on trains to varying degrees depending on several factors, such as ambient temperature, condition and age of the air brake equipment on each car, maintenance practices, and length of time the air brakes remain applied.

In most operating scenarios, some leakage is expected and it will not initially compromise safety. However, it can create a reduced margin of safety when a train brake system is relied upon for an extended duration.Footnote 1 If a critical loss of brake cylinder pressure occurs due to leakage effects, an uncontrolled movement can result.

As part of TSB’s ongoing investigation, preliminary calculations for a fully charged brake system (Annex B) indicate that:

  • If a train of similar configuration to the occurrence train (i.e., a loaded unit grain train) is stopped in emergency on a 1.75% grade, the train would require at least 50% of the expected emergency brake cylinder pressure to prevent any train movement.
  • On a grade of 1%, a similar train stopped in emergency would require at least 30% of the expected emergency brake cylinder pressure to ensure the train remains stationary.
  • If rail car brake cylinder leakage rates are nearing even half (50%) of the Association of American Railroads (AAR) condemnable limits,Footnote 2 safety can be compromised.

Based on the preliminary calculations, an uncontrolled movement of a train stopped in emergency for an extended duration can occur on grades of less than 1.8%.

Given the potential consequences of an uncontrolled train movement, Transport Canada may wish to ensure that effective safety procedures are applied to all trains stopped in emergency on both “heavy gradesFootnote 3” and “mountain grades”.  

Yours sincerely,

Kirby Jang
Director
Investigations, Rail/Pipeline

CC:

Assistant Vice President, Safety & Sustainability - Canadian Pacific Railway

Vice President, Safety and Environment - Canadian National Railway

Senior Counsel, Regulatory Affairs - Canadian National Railway

Senior Director, Operations and Regulatory Affairs - Railway Association of Canada

Appendices

Appendix A

Ministerial Order MO 19-03

Section 32.01 ofthe Railway Safety Act (RSA) provides the Minister of Transport with the authority to order a company, road authority or municipality to stop any activity that might constitute a threat

· to safe railway operations or to follow the procedures or take the corrective measures specified in the order, including constructing, altering, operating or maintaining a railway work.

On February 4, 2019, a Canadian Pacific Railway Company train, Number 301, was proceeding westward to Vancouver, British Columbia {BC) when the train was brought to a stop on a mountain grade using an emergency brake application. After a period of time, the train began to move and accelerated to a speed in excess of the maximum track speed and derailed. A total of 99 cars and 2 locomotives derailed between the Upper and the Lower Spiral Tunnel near Field, BC (Laggan Subdivision). The train crew on board consisted of a locomotive engineer, a conductor and a conductor trainee; all were fatally injured.

As the exact cause of the accident remains unknown, I find it necessary in the interest of safe railway operation and to prevent further accident in like circumstances, to order, pursuant to section 32.01 of the RSA, all railway companies and local railway companies listed in Appendix B to:

I. When a train is stopped by an emergency brake application on a grade of 1.8% or greater {i.e. mountain grade), immediately apply a sufficient number of handbrakes, in accordance with the attached Appendix A, before recharging the air brake system to prevent involuntary movement of the equipment.

This Order shall take effect on February 8, 2019, and will remain in effect until it is cancelled in writing by the Minister of Transport.

Pursuant to subsection 32.1 ( 1) ofthe RSA, a person to whom a notice that contains an order is sent under section 32.01 ofthe RSA may, on the date specified in the order, file a request for a review with the Transportation Appeal Tribunal of Canada (Tribunal).

If you intend to request a review of this Order, you must file a request in writing with the Tribunal, which must be postmarked no later than March 10, 2019.

Pursuant to section 32.3 of the RSA an order issued under section 32.01 of the RSA shall not be stayed pending a review requested under section 32. l, an appeal under section 32.2 or a reconsideration by the Minister of Transport under subsection 32. l(5) or 32.2.(3) ofthe RSA.

Brigitte Diogo
Director General, Rail Safety
February 8, 2019

Appendix A of Ministerial Order MO 19-03

Appendix A of Ministerial Order MO 19-03
Total Trailing Tons Average Grade Is Equal To Or Less Than
0.2% 0.4% 0.6% 0.8% 1.0% 1.2% 1.4% 1.6% 1.8% 2.0% 2.2% 2.4% > 2.4%
0 –   2000 10  10  12  12  14   
> 2000 – 4000 12  14  16  18  20  22  26   
> 4000 – 6000 10  14  16  20  24  28  30  34  38   
> 6000 – 8000 12  18  22  26  32  36  42  46  52   
> 8000 – 10000 10  16  22  28  34  40  46  52  58  66   
> 10000 – 12000 12  20  26  34  40  48  56  64  72  80   
> 12000 – 14000 14  22  30  40  48  58  66  76  84  96   
> 14000 – 16000 10  16  26  36  46  56  66  76  88  98  110   
> 16000 – 18000 10  18  28  40  50  62  74  86  100  112  126   
> 18000 – 20000 12  20  32  44  58  70  84  98  112  128  146   
> 20000 – 22000 12  22  36  50  64  78  94  110  100% Hand Brakes
> 22000 – 24000 12  24  38  54  70  86  104  122 
> 24000 – 26000 10  14  26  42  58  76  94  112  134 
> 26000 – 28000 10  14  28  46  64  82  104  124  148 
> 28000 – 30000 12  16  30  50  68  90  110  136  162 
> 30000 12  16  34  52  74  96  120  148  172 

Appendix B

Calculations of braking force and brake cylinder leakage

A graph of rail car brake cylinder pressure (BCP) for an emergency brake application is presented below. The Y-axis represents pressure in “psi” and the X-axis, time in “seconds”. The reduction in BCP due to leakage effects is colour-coded for five (5) different leakage rates. A “no- leakage” BCP is provided for reference. Annotations have been added to highlight a few key details.

As an example, the BCP trace shown in green corresponds to a leakage rate of 0.5 psi/minute. Starting from a BCP of about 78 psi, brake cylinder pressure reduces by 10 psi, and down to 68 psi in about 2000 seconds (33 minutes) after the application of the emergency brakes.

Figure 1. Brake cylinder pressure drop over time for various leakage rates (Source: Wabtec Corporation)
Brake cylinder pressure drop over time for various leakage rates (Source: Wabtec Corporation)

Scenario #1:  Loaded Train of 112 Grain Cars on a 1.75% Grade

The table below presents the calculation of the braking requirements to hold a 112-car loaded grain train stationary on a 1.75% grade. The calculations do not consider supplemental locomotive brake retarding force as may be available from the dynamic brake(s) (DB) and/or the independent brake(s). In addition:

  • DB may not be available in emergency braking scenarios; and
  • the use of full locomotive independent brake is restricted by train handling ‘best’ practices.

In the following sample calculation, a BCP of 37 psi is required, at a minimum, for the train to remain stationary on the 1.75% grade.

As shown in Graph 1, for a leakage rate of 0.5 psi/minute equivalent to 50% of the AAR condemnable limit, BCP would reduce to 37 psi in about 11 375 seconds (3 hrs and 10 mins).

BCP will leak down to 37 psi in even less time at higher leakage rates and/or when the brake system is not fully charged (i.e., emergency BCP initially less than 75 psi).

Brake cylinder pressure drop over time for various leakage rates (Source: Wabtec Corporation)
Data tables
Basic train data 
Number of railcars 112
Total weight on rail per railcar 286,000 pounds
Number of locomotives 3
Total weight on rail per locomotive 415,000 pounds
Total weight* 16,639 tons
Train speed** 15 MPH
Number of railcars with operative brakes 112
Tons per operative brakes (TOB)* 149 tons

* Values calculated from known or assumed values

** Speed used for Brake Horsepower (BHP) calculation however it does not influence the stationary braking effort calculation. 

Other basic data
Brake shoe coefficient of friction 0.3
Grade 1.75 %
Grade force 20 pounds / ton / grade percentage
Grade force exerted on train* 582,348 pounds

* Values calculated from known or assumed values

Braking effort
Retarding force needed* 582,348 pounds
Dynamic brake (DB) / locomotive 0 pounds
Dynamic brake (DB) total @ 75%* 0 pounds
Retarding force needed from air brakes* 582,348 pounds
Retarding force needed per railcar* 5,200 pounds
Braking force (BF) needed per railcar* 17,330 pounds
Braking force (BF) needed per wheel* 2,170 pounds

* Values calculated from known or assumed values

Air brake calculations, per railcar
Lever ratio (L) 8
Size of brake cylinder (diameter) 10 inches
Area of the brake cylinder (A)* 78.5 square inches
Number of brake cylinders (N) 1
Efficiency (E) 0.75
Braking force (BF)*, **, + 17,330 pounds
Brake cylinder pressure (P)*, ** 37 PSI
Brake pipe pressure drop*, *** 15 PSI
BHP per wheel*, **** 26 BHP

* Values calculated from known or assumed values

** Needed to control grade

*** Needed to develop required brake cylinder pressure

**** Brake horsepower (thermal input) per wheel 

+ Braking force = Product of brake cylinder pressure by lever ratio by brake cylinder area by number of brake cylinders by efficiency (BF = P x L x A x N x E)

Note: The speed of the train was included to calculate the Brake Horsepower (BHP). However, the speed value does not influence the stationary braking effort calculation. BHP is an important braking parameter for managing maximum allowable wheel tread temperature on rolling stock in motion. BHP is not relevant to a stationary train.

Scenario #2:  Loaded Train of 112 Grain Cars on a 1.0% Grade

The table below presents the calculation of the braking requirements to hold a 112-car loaded grain train stationary on a 1.0% grade (locomotive dynamic and independent brakes ignored).

In the following sample calculation, a BCP of 21 psi is required at a minimum for the train to remain stationary on the 1.0% grade.

As shown in Graph 1, for a leakage rate of 0.5 psi/minute equivalent to 50% of the AAR condemnable limit, BCP would reduce to 21 psi in about 18 330 seconds (5 hrs and 5 mins).

BCP will leak down to 21 psi in even less time at higher leakage rates and/or when the brake system is not fully charged (i.e., emergency BCP initially less than 75 psi).

Brake cylinder pressure drop over time for various leakage rates (Source: Wabtec Corporation)
Data tables
Basic train data 
Number of railcars 112
Total weight on rail per railcar 286,000 pounds
Number of locomotives 3
Total weight on rail per locomotive 415,000 pounds
Total weight* 16,639 tons
Train speed** 15 MPH
Number of railcars with operative brakes 112
Tons per operative brakes (TOB)* 149 tons

* Values calculated from known or assumed values

** Speed used for Brake Horsepower (BHP) calculation however it does not influence the stationary braking effort calculation.

Other basic data
Brake shoe coefficient of friction 0.3
Grade 1.00 %
Grade force 20 pounds / ton / grade percentage
Grade force exerted on train* 332,770 pounds

* Values calculated from known or assumed values

Braking effort
Retarding force needed* 332,770 pounds
Dynamic brake (DB) / locomotive 0 pounds
Dynamic brake (DB) total @ 75%* 0 pounds
Retarding force needed from air brakes* 332,770 pounds
Retarding force needed per railcar* 2,970 pounds
Braking force (BF) needed per railcar* 9,900 pounds
Braking force (BF) needed per wheel* 1,240 pounds

* Values calculated from known or assumed values

Air brake calculations, per railcar
Lever ratio (L) 8
Size of brake cylinder (diameter) 10 inches
Area of the brake cylinder (A)* 78.5 square inches
Number of brake cylinders (N) 1
Efficiency (E) 0.75
Braking force (BF)*, **, + 9,900 pounds
Brake cylinder pressure (P)*, ** 21 PSI
Brake pipe pressure drop*, *** 8 PSI
BHP per wheel*, **** 15 BHP

* Values calculated from known or assumed values

** Needed to control grade

*** Needed to develop required brake cylinder pressure

**** Brake horsepower (thermal input) per wheel 

+ Braking force = Product of brake cylinder pressure by lever ratio by brake cylinder area by number of brake cylinders by efficiency (BF = P x L x A x N x E)


Note: The speed of the train was included to calculate the Brake Horsepower (BHP). However, the speed value does not influence the stationary braking effort calculation. BHP is an important braking parameter for managing maximum allowable wheel tread temperature on rolling stock in motion.  BHP is not relevant to a stationary train.

Background information

Occurrence No:

R19C0015

Contacts:

Don Crawford, Regional Senior Investigator, TSB Calgary, Alberta

Robert LeBlanc, Regional Senior Investigator, TSB Edmonton, Alberta

Dan Holbrook,Manager, Head Office and Western Regional Operations, TSB Gatineau, QC

Date modified: