I wonder how they cope in countries with a far greater temperature range, such as Hungary? Perhaps the steel used for the rails has a different composition - could it have a lower coefficient of expansion?
I wonder how they cope in countries with a far greater temperature range, such as Hungary? Perhaps the steel used for the rails has a different composition - could it have a lower coefficient of expansion?
The variation in the coefficient over the range of common steel alloys is quite small, so I would think that this difference will not be significant, amounting to about 40 mm in 1km of free unballasted rail over a temperature range of, say, 40K, and rather less in an actual installation (if my thumbnail arithmetic is correct).
Network Rail are reassuring the public that railways are safe, but I expect they are concerned.
The reports on these two derailments will be interesting (if technical) reading.
Might not end up being technical, perhaps more about assurance, EWATs etc
Indeed, but there must surely be a fair amount of technical and/or scientific detail.
True, but I was just wondering what the main focus of the report will be.
Yes, I see. As you say, there will no doubt be a good deal of reassurance.
Railways have a very good safety record these days, but this is sometimes overlooked by the popular press.
One wonders if it suddenly buckled with the stress of the train passing over. We can see that some ballast sacks were stacked nearby, perhaps the ballasting hadn't been tamped properly.
The anecdotal reports of rough riding remind me of the 1967 Hither Green disaster. Although the Hastings units, due to their design, did tend to ride roughly (as did the 1930s Southern Railway express EMUs including the "Brighton Belle"), the cause of the accident was a broken rail due to poor maintenance and the punishing effect on the track of multiple units with axle-hung motors. It's clear that the "irregularity" did not of itself cause the derailment as other trains, and indeed the front carriages of this train, passed over it safely.
So either rails buckled suddenly as the train passed over, due to excessive stress caused by heat or embankment subsidence; or (less likely) there was a failure on the train itself. The dreadful Enschede high-speed derailment in Germany, we mustn't forget, was caused by a broken wheel.
The statement was, 'Initial findings from the Rail Accident Investigation Branch (RAIB) found an "irregularity" '. That is an observation; not a conclusion. It will be one of many before this is over, and whether the media like it or not, we have to wait for the conclusions to be drawn by the people qualified to do it.
Indeed so. One point about the RAIB investigations is that they do not only give the immediate cause of an accident but go into the background factors which may have led to it. For instance, if an accident was caused by a broken rail, they'll want to know why that happened - poor quality manufacture, improper installation, lack of or inappropriate maintenance ... And then they'll further back still and look at structural, management and human issues that may have been involved. All very interesting!
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The variation in the coefficient over the range of common steel alloys is quite small, so I would think that this difference will not be significant, amounting to about 40 mm in 1km of free unballasted rail over a temperature range of, say, 40K, and rather less in an actual installation (if my thumbnail arithmetic is correct).
True, but I was just wondering what the main focus of the report will be.
Yes, I see. As you say, there will no doubt be a good deal of reassurance.
Railways have a very good safety record these days, but this is sometimes overlooked by the popular press.
So either rails buckled suddenly as the train passed over, due to excessive stress caused by heat or embankment subsidence; or (less likely) there was a failure on the train itself. The dreadful Enschede high-speed derailment in Germany, we mustn't forget, was caused by a broken wheel.
I feel it was premature, and the future report may now be hemmed in by the interim report too.