Blow Down Derailment

We had an unusual - for the Pacific Northwest - weather occurrence,  an F1 tornado (up to 125 mph / 200 km/h) had touched down south of Tacoma at Frederickson Washington. These five cars were not moving when the tornado dropped down. They were spotted at the entrance to Boeing's Frederickson Complex.

According to the Puget Sound Business Journal, "work was halted at Boeing's Frederickson plant south of Tacoma Monday morning after a tornado tore between two buildings, damaging part of a roof and about two dozen cars. No one was injured.

"The vertical stabilizer and tail fins for the Boeing 777 and 787s are made at the Boeing Frederickson facility, consisting of two major manufacturing business units - composite manufacturing center and skin and spar."

"The question I asked myself became one of;  "how strong a wind is required to blow down a set box cars, and how often does it occur?"

Well, it turns out that "blow down" derailments are not unheard of!

In fact, several weeks ago, on September 3rd, the Transportation Safety Board of Canada (TSB) released its final report (Railway Investigation Report R12W0165)  into the July 29, 2012 derailment of a Canadian Pacific (CP) freight train in Popular Point Manitoba.

TSB concluded that high winds were the cause of a train derailment, saying a delay in notification to the train crew about severe weather in the area led to the crash!

The train departed Winnipeg and began traveling westbound to Brandon on CP's Carberry subdivision when the accident occurred at around 6 p.m. The TSB says cars were double stacked with empty containers when it was traveling at around 43 km/h (27 mph.) Twelve cars of the 56 on the track blew over as a result of the strong wind gusts and rain.

CP's crew received a radio call about the weather, but it was too late to take the necessary precautions.

The railway has since taken steps to amend its severe weather warning procedure to ensure train crews are aware of the risk of encountering high winds:

CP RTC Manual - Section 3.5 – Severe Weather Warning Procedure 

When advised by the Supervisor that a severe weather warning is in effect, the RTC must:

1. Not perform any other non-emergency task until they have: •advised all movement(s) within, or immediately approaching the affected area of the weather alert information [item 2(i)];
• placed a general bulletin order (GBO) block (CTC or OCS) as applicable over the affected area; and
• recorded in Train Information and on RTC Planning sheet the details and location of the weather warning.

2. Contact all movement(s) that will encounter the weather warning area(s) and:
• advise them of the weather alert information; and
• determine from the operating crew(s) the local conditions.

3. Communicate the local conditions [item 2(ii)] to the Supervisor for determination of operating plan.

4. Verbally advise movement(s), as per the Supervisor’s request, to:
• stop;
• proceed prepared to stop short of any condition which may affect safe passage and in no case exceeding 25 mph; or
• proceed at authorized track speed.

5. Not remove any restrictions placed on movement(s) until advised that:
• the weather warning alert is cancelled;
• the track has been inspected and reported as safe for movement(s); or
• the weather within the area is clearing as determined by crew(s) on movement(s) and the Supervisor advises that it is safe to do so.

Other recent wind-related derailments 

•  August 9, 2012 "Coal Train Derails" (average coal car carrying in excess of 100 tons!)
•  June 17, 2013 "Wind causes train derailment near Hereford, Texas"
•  July 18, 2013 "High winds topple seven cars in Chicago"
•  BNSF Dispatcher broadcasts high wind warnings (turn sound up.)

Following a dramatic derailment Down Under, the Australian Transport Safety Bureau (ATSB) undertook a detailed analysis, including wind tunnel experiments, to understand the dynamic forces that affect safe rail operations.

"On 1 November 2006, a freight train derailed near Tarcoola, South Australia (there were no injuries). Tarcoola is a small, remote town in central South Australia where the rail line from Darwin (in the north) joins the main east-west rail line crossing Australia.

 "The freight train had been traveling from Darwin to Adelaide. As it approached Tarcoola from the north, the drivers noted a significant amount of lightning in nearby thunderstorms.

"While traveling at about 65 km/h (40 mph), the driver felt a slight tug and/or surge through the locomotives. The driver also observed (via the locomotive gauges) a reduction of brake pipe pressure and an increase in brake pipe airflow. The train slowed to a stop and one of the drivers walked back to inspect the train.

"He discovered that only 16 of the 31 wagons were coupled behind the locomotives. Walking further back along the track, the driver found the remainder of the wagons, some of which had derailed and were lying on their side."

On 11 November 2008, a freight train derailed near Loongana, Western Australia (there were no injuries). Similar to the derailment at Tarcoola, the train was loaded with double-stacked freight containers, though in this case they were loaded on a flat wagon. Again, the containers were mostly empty.

The freight train had been traveling from Perth to Melbourne. As it traveled on a long straight section of track near Loongana, the drivers observed pockets of lightning and wind induced dust moving towards them from a north to northeasterly direction.

The train had been traveling at about 105 km/h (65 mph), but the wind caused the train speed to rapidly reduce. The driver estimated that the train lost about 35 km/h (23 mph) over a distance of about 3.5 km (2 miles), despite the throttle being set at eight notches (full power).

As with the Tarcoola incident, the site evidence was not consistent with what would normally be expected at a derailment site. It too appeared as though the wagons had simply tilted and rolled over onto their side. (Source: A Blow to Train Operations, Can strong winds cause derailment? Tony Simes, Senior Transport Safety Investigator (Rail) Australian Transport Safety Bureau.)

When you read the final findings, there was no evidence of flange climbing, which lead to the conclusion that the wagons (cars) simply tilted

over until they crossed the center of gravity and dropped on their sides.

And so while it seems impossible for a heavily laden freight train to be derailed by high winds, there is plenty of empirical evidence to support such a notion!

Addendum

Australian Government, Transportation Safety Board, Final Report on derailment at Loongana. Locomotives involved in the blow down at Loongana were 4,020 hp National Rail  NR 101 on the bow, and sister NR 62 distributed power on the stern.

•  NR 101 (named "Crystal Brook / Redhill") In service July 21, 1997.
•  NR 62 (named "Tarcoola") In service November 1, 1996

•  Builder: Bassendean: NR61-NR120 Model Cv40-9i
•  Build date 1996-1998
•  Total produced 120 AAR wheel arr. Co-Co UIC classification Co'Co'
•  Gauge 1435mm (Standard Gauge)
•  Length 22.00 m (72 feet)
•  Locomotive weight 132.00t (metric)
•  Engine type GE Transportation Systems 7FDL-16
•  Generator GE GMG196 Traction motors GE 5GE793A1
•  Top speed 115 km/h (71 mph)
•  Power output 3000 kW (4020 HP)

Conclusion

Because of the weights involved, it's hard to believe weather can derail a train! However, based on wind tunnel tests conducted by the Transportation Safety Board of Canada,  the Blow Down Derailment is a demonstrable phenomenon.

An associate sent along a link to a Blow Down Derailment caught on tape.  See Steve Boyko in "Comments" below.