Latest Rail News

30.06.15

Heatwave causes rail buckling and points failure fears in Thames Valley

First Great Western (FGW) services in the Thames Valley area will be subject to speed restrictions from midday until 8pm today over fears of rails buckling. 

Network Rail has advised that, due to the anticipated exceptionally hot weather in the area, there will be speed restrictions to protect track points. The Met Office has forecast that temperatures are set to hit 30°C in parts of the Thames Valley. 

This will mean there will be no fast trains between London Paddington and Bourne End or Henley-on-Thames. 

Network Rail said “as rails are made out of steel, they expand as they heat up and are subject to strong compression. 

“This expansion has to be managed to reduce the risk of track buckling. If the track does buckle, the line must be closed and the track repaired before services can resume, causing considerable disruption.” 

Trains from London Paddington will terminate at Twyford for a connection with a branch line service to Henley-on-Thames. 

Passengers travelling to Bourne End from Paddington will see their services terminate at Maidenhead and will also have to complete their journey on a branch line train. 

An FGW spokeswoman told RTM that the measures had been put in place as a “proactive” measure to avoid greater disruption, and the points that could potentially be affected by the heat are legacy points.

FGW announced the restrictions will affect the following services: 

London Paddington to Henley-on-Thames 

Trains from London Paddington will terminate at Twyford for a connection with a branch line train to Henley-on-Thames, which will remain on the branch line. 

17:12 London Paddington to Henley-on-Thames, this service will terminate at Twyford.

18:12 London Paddington to Henley-on-Thames, this service will terminate at Twyford.

19:05 London Paddington to Henley-on-Thames, this service will terminate at Twyford. 

London Paddington to Bourne End 

Trains from London Paddington will terminate at Maidenhead for a connection with a branch line train to Bourne End, which will remain on the branch line. 

16:42 London Paddington to Bourne End, this service will terminate at Maidenhead.

17:42 London Paddington to Bourne End, this service will terminate at Maidenhead.

18:42 London Paddington to Bourne End, this service will terminate at Maidenhead. 

Update 

Network Rail has sent out a briefing note on the issue of ‘Minimising disruption during hot weather’ and what it is doing to prevent track buckling. 

Network Rail said efforts include: 

  • Each part of the network being risk-assessed so that we know at what rail temperature the risks of track buckling are increased.
  • We check the stability of the track each winter and strengthen any weaknesses before the summer arrives; typically this includes replenishing the ballast that surrounds the sleepers, and re-tensing (stretching) continuously welded rails.
  • We plan to avoid work that will disturb the stability of the track during the summer as this increases the chance of a track buckle, though sometimes it cannot be avoided.
  • We paint at-risk rails white so they absorb less heat, reducing rail temperatures. Typically a painted rail will be five to ten degrees cooler than an unpainted rail.
  • We have also introduced sprinkler systems to cool rail temperatures at key junctions and during trials these have reduced temperatures by four degrees in ten minutes.
  • We are continually enhancing our measures for calculating rail temperatures, including installing probes that give us instant alerts when track temperatures rise.
  • On very hot days when high rail temperatures are widespread, we impose speed restrictions at vulnerable locations; slower trains exert lower forces on the track, reducing the risk of buckling. 

The briefing note also addresses future solutions and discusses the use of slab track rather than ballasted systems. 

“Some countries use ‘slab track’ where track is laid on reinforced concrete slabs rather than on sleepers and ballast, preventing tracks from buckling,” it said. But the installation cost of slab track is typically four times that of track laid on sleepers and ballast. “Even taking into account the savings in maintenance and disruption costs, it's hard to make a business case for slab track, though we are working with suppliers to see how we can get the costs down,” said Network Rail.

Tell us what you think – have your say below or email opinion@railtechnologymagazine.com

Comments

Terry K   30/06/2015 at 11:51

Does this mean our modern up to date railway can only run when the sun does not shine. according to the weather forecast we will have 2 weeks of this hot weather, will the passengers put up with the delays?

Juanjo   30/06/2015 at 15:54

There must be easier solutions, as we don't stop trains in Spain when the sun shines. And it shines, believe me.

Pedr   30/06/2015 at 18:23

Indeed, Juanjo, but do you also have to cope with temperatures of minus 30deg C in the winter?

Retired Engineer   30/06/2015 at 20:50

NWR's tracks have to contend with a wide range of heat and cold. The current weather is exceptional - how many days do we have 30 degrees? Thus our railway is a compromise to cope with a variety of temperatures. Heat buckling can derail trains and kill passengers. Would the passengers put up with that Terry?

Henry Law   30/06/2015 at 20:57

This subject is discussed here. It is easy to be critical when you do not know the technical issues involved. https://en.wikipedia.org/wiki/Rail_stressing

Juanjo   30/06/2015 at 22:52

Minus 30º C is not a temperature you can register in London. Compare temperatures in London with those in Madrid or Granada, for example, and you will see there must be simple ways to cope with the problem.

Ian   30/06/2015 at 23:15

I recall that we went through many years where expansion joints were replaced by stressed continually welded rail. I do not recall as many problems with buckling when expansion joints took up the expansion. Are my recollections accurate?

Grace   01/07/2015 at 10:15

I am only a humble signal engineer, but have worked with track engineers for many years. Ian; jointed track expands at each joint so far as it can, but buckling was far more common on jointed track than it is with CWR. A point which as not been clearly made is that at low temperatures when the rails contract and are therefore in tension (rather than compression when hot) the risk of rail breaks grows, so as Henry pointed out in the wiki article, in the UK rails gets pre-stressed to be under neutral stress when the RAIL temperature is 27deg. Sun on rail always heats the rail to well above ambient temperature. Juanjo, in Spain that temperature would be higher, in Norway it would be lower. We are dealing here with physical limits, and as Scotty said many times "you canna change the laws of physics"

Keith   01/07/2015 at 16:27

What do they do in countries like Thailand or Indonesia, where the temperatures are regularly above 30C on almost every day of the year ???

Ray   01/07/2015 at 20:45

Am I missing something? This announcement relates only to two branch lines - not the whole of the Thames Valley network! The caution seems to be a combination of cost/benefit engineering and good common sense!

Retired Engineer   01/07/2015 at 22:24

Oh dear Keith! Thailand and Indonesia (and other countries) may be able to cope with 30C but how often do they have to cope with temperatures BELOW 0degreesC? Network Rail track is a compromise between high and low temperatures. Norway has generally LOW temperatures, Indonesia has generally HIGH temperatures. British track is stressed for an AVERAGE temperature to suit most conditions. It is not possible to accommodate ALL conditions, as Grace correctly said "Ya canna change the laws of physics".

Retired Engineer   01/07/2015 at 22:27

Well said Grace. After 35 years working in the S & T I always found the worst time for broken rails was April - warm days, cold nights. When I was on shifts if we had a track circuit failure in an April night we always took bets on it being a broken rail. And we were usually right,too.

Retired Engineer   02/07/2015 at 10:25

Indonesia lies on the Equator so is warm all year round. According to various reputable websites the rail system in Indonesia is "old and poorly maintained" and "rail services....have poor safety records", "the Ministry of Transportation has set a goal of reducing the number of fatalities....by 50 per cent". Film of Indonesian trains on YOUTUBE shows passengers clinging to the outsides of trains as they are running.Which system would you prefer to travel on? This is my last post on this.

Scottie   03/07/2015 at 09:33

In the UK we have one of the most expensive to build and maintain networks in the developed world, not to mention the some of the most expensive fares as well to boot ! Madrid copes perfectly well with temps of 40C + in summer and below freezing winter temps. Why are our standards of track laying and maintenance inferior in the UK, given that our track is some of the most expensive to lay anywhere in the world ! It would appear that once again in the UK that profit margins/costs are more important than excellent, reliable and robust track standards !

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