POSTED 10.01.17

In the second of our regular blogs, resident EASL Rail enthusiast Andrew Inkersole takes a look at the world of engineering on railway safety. Following on from the nuclear flask crash test of 1984, let’s delve into some of the structural integrity measures associated with locomotives and rolling stock.

Last time I wrote about the nuclear flask crash test that was staged in the 1980s with the intention of demonstrating to the public that a nuclear waste flask could survive the impact of a rail crash. However, even though this event proved a success for those designing the nuclear waste flask, it’s undeniable that for those considering the safety of the locomotives (and other associated passenger cargo!), it presented a slightly different picture.

Train crashes

I promised that I would give some consideration to how the railway industry has focussed on the “crashworthiness” of trains over the interim years and also on the general suitability of the crash test.
The improvements in the crash worthiness of trains was demonstrated by the derailment at Grayrigg on the 23rd February 2007. The train involved was a nine-car Class 390 ‘Pendolino’ electric multiple unit which had entered service in 2002 some 40 years later than the class 46 used in the crash test. It would have been travelling at a similar speed to the Peak when it hit the flask.

The RAIB investigation into the derailment at Grayrigg noted that the crashworthiness performance of the class 390 avoided, almost completely, a number of hazards. These included ejecting passengers through windows, reducing survival space, and external structures penetrating the passenger compartment, all of which have caused fatal and serious injuries in the recent past.
Notable features that held particular value in minimizing passenger injuries were:

• Laminated windows which largely contained passengers within the train;
• Robust couplers which generally kept the vehicles together;
• Anti-roll bar links which ensured that most of the bogies remained attached to the train; the penetration resistance of the bodyshell; and
• The roll-over strength of the bodyshell.

Suitability of Crash Test

As regards the suitability of the test the obvious comment is that the flask was free to move after the impact. Visualizing a collision in, let’s say, a solid rock cutting, makes it easy to understand how the flask could experience a higher impact load.

The choice of locomotive was reasonable as the class 46s were at the heavier end of the first generation diesels and had little in the way of a crumple zone. Further, the trailing load was benign in the sense that there were no corrosive chemicals or flammable liquids on board (which a train travelling in the opposite direction to a derailed flask may have).

I suspect that studying the footage of the incident and the behaviour of the locomotive and the attached coaches after the moment of impact has been useful to engineers in the development of the crash worthiness of trains.
So, all things considered, it would be wrong to say that despite the clear impact (no pun intended) it left on viewers, this exercise was not merely a publicity stunt.

Do you believe that railways have become safer? Was the crash test suitable for the collision? Let us know on twitter @easlstress or get in touch on our contact us page.


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