First speed restriction of the season due to heat today

[whole diary]

[woody]

Apparently there was a speed restriction today between Truro and St Austell due to heat in the Burngullow area I was told.

[Louis94]

Line problem between Plymouth and Penzance.
Train services are being disrupted due to speed restrictions between Plymouth and Penzance.Delays of up to 45 minutes can be expected.
Last Updated: 20/04/2011 16:18

Any idea what's going on in Cornwall, wouldn't be something to do with the hot weather?

[Andy]

As the tourist season gets under way, it's to allow time for passport and visa inspections on international trains from across the Tamar. 

[jester]

 

[LiskeardRich]

a friend was travelling between penzance and truro today this is his facebook status

ok so network rail have put a speed limit of 20 mph due to hot track only in cornwall

3 hours ago via Mobile Web

[marky7890]

Trains were also going slow in the Redruth area.

[Branch Line Connor]

How does hot weather affect trains?

We stop when it gets too cold, now when its too hot- What are we, a March & October only service

[JayMac]

How does hot weather affect trains?

A sharp change of temperature from cool to hot or vice versa can lead to rails expanding or contracting too much and thus affecting gauge, usually only slightly. Modern continuously welded rail is supposed to be securely tied to sleepers to prevent excessive expansion or contraction.

Ideally, rails are laid at a median temperature between what is expected to be the highest and lowest ambient temperature in that area. This is obviously not an exact science and extremes of temperature can cause problems and the ties may fail to cope with the expansion/contraction. Despite this, gauge is usually maintained within acceptable limits, (sometimes with expansion joints in known problem areas) but speed restrictions maybe put in place as a precaution.

Just occasionally the expansion/contraction is so severe as to break the gauge between rails, but this is very rare and there have been few, if any, incidences in modern times of a derailment of a passenger service from this cause.

[woody]

Yesterday the 1400 Penance/Paddington due off Exeter at 1702 finally arrived at Exeter at 1753 due to the speed restrictions caused by the heat.Was told yesterday that Network Rail had lowered the temperature/speed restriction threshhold to 26 degrees Centigrade which had triggered the speed restrictions in Cornwall.If thats the case God help us then if we get a decent summer this year in Devon and Cornwall.

[LiskeardRich]

its just as hot today, so assuming more of the same, 25C in my garden at 12 today, (i live approx 100 metres from penryn station)

[inspector_blakey]

For an example of what can happen in hot weather, see here:

http://www.raib.gov.uk/publications/investigation_reports/reports_2010/report062010.cfm

The cover sheet of the report says it all.