Failures in hot weather. What needs to change?

[Centralsimon]

Thanks for the info. I wonder too whether proximity to a station led to concerns about self-evacuation if the doors were opened, even with the barriers in place.

Sympathies for your ordeal BTW.

It was definitely time and onboard conditions that increased the risks. The onboard staff were in control and this mitigated this, but eventually patience ran out. RDG guidance states that an uncontrolled evacuation risk increases significantly after 90 mins.

I suggest most on board never knew who close Knebworth was and if they did, the uncontrolled evacuation onto a 100mph line would have happened sooner.

A breakdown in command and control and a failure to meet RDG timelines

Are we confident lessons learnt, are we confident industry willing to learn lessons ?

Or do we wait for our luck to run out?

 

[Russel]

Same old, same old with the railway industry. So far up its own self obsessed backside it forgets that there are real people on its trains.

It’s nothing new, either. Back in June 2005, several GNER Mark 4 sets lost power during an OHLE incident on a hot day. Sound familiar? In that case passengers resorted to breaking windows to get fresh air.

20 years on and it’s still the same. No doubt trite “lessons will be learned” statements will be made. But they aren’t. It is a complete and utter disgrace.

Couldn't have put it better myself.

 

[Bletchleyite]

One relatively low cost mitigation might be to mandate that all a/c coaches have one emergency openable window on each side, to permit some degree of through ventilation. It could be kept locked by the same power supply as feeds the a/c, so that a failure of the a/c supply automatically releases the locks.
I doubt if anyone would want to spend the money on the mk4s, but this is likely to recur on other stock in the future.

To me the best mitigation is to mandate that all new build rolling stock (and retrofit where possible) is fitted with battery packs that can maintain full HVAC for a minimum of four hours (as evacuations typically take about three), and perhaps fan-only ventilation for a further hour, plus at least one toilet fully functional per train throughout. Ideally these should also be capable of moving the train a short distance at low speed (say 10mph) to ease the actual evacuation.

As an alternative to the toilet requirement an option would be to carry emergency folding "cat litter" bag-and-box toilets which could be used in the disabled toilet room. These are commonly available for camping purposes.

A further sensible measure would be the scrapping of all the old Mk4s as they have been worked hard so will be unreliable, but aside from TfW's that is planned soon anyway when the CAF units arrive.

 

[43096]

To me the best mitigation is to mandate that all new build rolling stock (and retrofit where possible) is fitted with battery packs that can maintain full HVAC for a minimum of four hours (as evacuations typically take about three), and perhaps fan-only ventilation for a further hour, plus at least one toilet fully functional per train throughout. Ideally these should also be capable of moving the train a short distance at low speed (say 10mph) to ease the actual evacuation.

As an alternative to the toilet requirement an option would be to carry emergency folding "cat litter" bag-and-box toilets which could be used in the disabled toilet room. These are commonly available for camping purposes.

That’s just addressing symptoms rather than causes.

A further sensible measure would be the scrapping of all the old Mk4s as they have been worked hard so will be unreliable, but aside from TfW's that is planned soon anyway when the CAF units arrive.

We have had similar situations on other, newer, stock.

The answer is to address the industry’s fundamental shortcomings on such situations. The railway has wrapped itself in so much H&S bureaucracy around operations that it cannot see past. Health & Safety in the industry is (or should be) more than just train operations. I suspect it is going to take a mass hospitalisation (or worse) event and subsequent prosecutions before the railway realises it.

 

[Benjwri]

To me the best mitigation is to mandate that all new build rolling stock (and retrofit where possible) is fitted with battery packs that can maintain full HVAC for a minimum of four hours

You're talking about 540kWh there, that's more than the battery FLIRTs capacity. Where are you planning on putting all those batteries?

 

[Bletchleyite]

You're talking about 540kWh there, that's more than the battery FLIRTs capacity. Where are you planning on putting all those batteries?

If it's not feasible to do it with batteries, then diesel generators as many "electric only" 80x have (and Lumo should have had apart from their anti-diesel foolishness on which they have now had to backtrack due to the highly polluting 222s they will run on WCML services).

The point is that if an expected evacuation time is 3-4hrs then there needs to be provision to heat/cool the train and provide toilet facilities for that whole period. This is not optional, particularly given that people with disabilities may have more heat/cold issues and may require more frequent toilet use. And if it can move the train too (even if slowly) then you can potentially in some cases shorten that period.

 

[geoffk]

To me the best mitigation is to mandate that all new build rolling stock (and retrofit where possible) is fitted with battery packs that can maintain full HVAC for a minimum of four hours (as evacuations typically take about three), and perhaps fan-only ventilation for a further hour, plus at least one toilet fully functional per train throughout.

Surely a non-tech solution is better, e.g. fitting all new rolling stock with some opening windows (I mean the hopper type as used on 158s). This would be the simplest way of dealing with air con failure (and retro-fitting existing stock when the opportunity arises).

 

[Trackman]

You're talking about 540kWh there, that's more than the battery FLIRTs capacity. Where are you planning on putting all those batteries?

I was going to say, they need a hell of a lot of power.

 

[AndrewE]

Thanks for the info. I wonder too whether proximity to a station led to concerns about self-evacuation if the doors were opened, even with the barriers in place.

Given the proximity of a station and the length of the dwell without power, ventilation or bog access - and thinking about the guidelines mentioned upthread - I am amazed that the lock-in was persisted with. Maybe having made a decision nobody was prepared to challenge the party line or re-think it? Getting the able-bodied people out would have made it a lot easier to look after the people who couldn't evacuate.

Looking at Google earth satellite view there don't seem to be any serious obstacles, it should surely have been possible to block the slow lines for a while and evacuate people the 200m back to the station along the adjacent slow line?

 

[Falcon1200]

it should surely have been possible to block the slow lines for a while and evacuate people the 200m back to the station along the adjacent slow line?

I would expect all lines would have to be blocked for however long it took to get the passengers off the train and to a place of safety; But given the delay this should perhaps have been looked at sooner. Although at the start of an incident like this no-one knows how long it will go on for, and what else might go wrong.

 

[Bletchleyite]

Surely a non-tech solution is better, e.g. fitting all new rolling stock with some opening windows (I mean the hopper type as used on 158s). This would be the simplest way of dealing with air con failure (and retro-fitting existing stock when the opportunity arises).

It doesn't work at all well unless the train is moving.

 

[JohnofWessex]

It doesn't work at all well unless the train is moving.

Having been on a set of MK1's stopped outside Exeter St Davids on a hot sunny day I can vouch for that but its better than nothing

 

[Snow1964]

Even though SWR now has a fully air conditioned fleet (took them 38 years since first 442 in late 1987), they have put a banner headline on their website advising passengers to carry water.

I question is this reasonable to expect passengers to carry water, or should it be SWR carries water on all its trains as back up if the air conditioning fails, rather than expecting passengers to carry it speculatively.

There is a more general question, of it temperature is expected to be above about 25c, should working air conditioning be seen as safety critical, like maintained brakes, and no train released from depot with it unrepaired.

 

[dosxuk]

In the sort of temperatures we're expecting this week, carrying water should be a default for everyone. It needs public bodies to be doing this sort of messaging, as well as I'm the background making sure that they have sufficient stocks for emergency situations themselves, because people will underestimate how the heat affects them.

There's no air conditioning on platforms, where people will be standing out in the direct sun. No amount of water carried on trains will help people getting dehydrated that way, while a little bottle of water in a bag will be a massive help to them.

 

[Russel]

I question is this reasonable to expect passengers to carry water, or should it be SWR carries water on all its trains as back up if the air conditioning fails, rather than expecting passengers to carry it speculatively.

We're about to have multiple days where the temperature exceeds 30 degrees, it should go without saying that you should be carrying water, SWR shouldn't have to remind people.

 

[Snow1964]

We're about to have multiple days where the temperature exceeds 30 degrees, it should go without saying that you should be carrying water, SWR shouldn't have to remind people.

Thats my view too, people should not need reminding,

At same time SWR advertises that its fleet is air conditioned, and with multiple days over 28c (even to mid to high 30s) should see it as safety to ensure all its trains have it functioning properly so that people dont get caught out by unacceptable temperatures inside.

 

[AndrewE]

In the sort of temperatures we're expecting this week, carrying water should be a default for everyone. It needs public bodies to be doing this sort of messaging, as well as I'm the background making sure that they have sufficient stocks for emergency situations themselves, because people will underestimate how the heat affects them.

I would rather not drink water that has been sat bottled in plastic for weeks, months or years as it has a very high bug load compared to tap water. In addition that would be millions more plastic bottles in circulation or - worse - thrown away unused at the end of their shelf life. Taking a refillable container of some sort from home is easily managed and there are more and more refill points available nowadays.

There's no air conditioning on platforms, where people will be standing out in the direct sun. No amount of water carried on trains will help people getting dehydrated that way, while a little bottle of water in a bag will be a massive help to them.

A little bottle of water won't stop them getting sunburnt. An umbrella (parasol) is the obvious answer, as well as having brought some water, but I think this obsession with sipping all the time is wrong. You can have liquid at meals and then work hard in heat and only need a drink at the next break (which might well be sooner in hot conditions.) The body contains lots of water and you can draw it down a long way before refilling afterwards.

If you are trapped in a hot place then don't panic, sit quietly and have a drink when you feel uncomfortable then go back to sitting quietly. Forget the histrionics or frantic broadcasts on public media.

p.s. I should also have said that you need salt too (and maybe a bit of sugar.) Very dilute lemon or orange squash with a pinch of salt in half a pint (so that you can just taste it) is a good idea.

 

[ainsworth74]

Having been on a set of MK1's stopped outside Exeter St Davids on a hot sunny day I can vouch for that but its better than nothing

Agreed. Obviously the best thing is a train with working aircon that's keeping the inside temperature at nice comfy 20 odd degrees (or ideally cooler, but I accept I like it cooler than many!). But if the aircon has fallen over (due to a unit failure or a failure of the power supply) then having opening windows is a life saver. A 158 with failed aircon but with its emergency hopper windows open is tolerable in all but the most extreme conditions compared to a sealed vehicle in the same position. Or even a Mk3 I had years ago between Wakefield and Darlington, aircon was knackered but with the drop-lights in the vestibules open and the carriage gangway doors locked open when the train was moving it was comfortable enough. We do need to, in my view, start building all trains with some emergency ventilation capability which ideally can be used whilst the train is in motion (so not just opening doors with barriers to stop people falling out).

It's also a strength of LNERs that even their electric units have a diesel engine which can power onboard facilities like aircon even when the wires are de-energized. I do wonder if that is also something that should be rolled out a bit more widely (or alternatively batteries capable of doing the job fitted).

But that's the main thing that needs to change in my view for failures in hot weather. We've got to have some facility of allowing even a modicum of fresh air to flow if the aircon fails. After all the longer you can keep the conditions on the train tolerable (even if not comfortable) the longer the railway then has to deal with whatever caused a train to get into that situation to begin with. If all your trains are sealed tubes with no facility to ventilate then they're going to have to come out of service or be rescued far quicker. And you'll end up with a far bigger incident once people start cracking doors and decanting themselves.

I would rather not drink water that has been sat bottled in plastic for weeks, months or years as it has a very high bug load compared to tap water.

Bottled water is safe to drink for years after it's been bottled. There isn't a "high bug load" or anything else in it. It should be thrown away after a couple of years as the plastic itself will start to degrade and could leach some chemicals into the water but that's why all bottled water manufacturers print a best before date of around two years post manufacture as after that point the plastic might begin to degrade. But even then the water is still safe (it's a best before not use by). I think we can be sure that it's highly unlikely any bottled water is likely to be sat around for long enough on a train for that to become an issue...

 

[Snow1964]

We do need to, in my view, start building all trains with some emergency ventilation capability which ideally can be used whilst the train is in motion (so not just opening doors with barriers to stop people falling out).

Yes even if it just battery powering the fans without the compressor and fans running.

Of course just fitting one system per carriage rather than two, so at least got half power is designing on assumption that depots won't skimp on maintenance when hot and treat it as some sort of optional extra that it acceptable not to fix, and put hot carriage in service.

When it is over about 26-28c, should be rule train gets swapped or a/c repaired, not that carry on running it regardless to cover inability to maintain. It would put more focus on priotity in hot weather.

 

[Bletchleyite]

Yes even if it just battery powering the fans without the compressor and fans running.

The answer here is probably indeed related to batteries. All EMUs should be fitted with a battery that can power basic HVAC, emergency lighting and toilets (perhaps with a higher temperature level than standard with fans, say 25 degrees max) for four hours, given that most evacuations seem to take about three. The battery should be capable of moving the train to the next station at 5-10mph if that is an easier evacuation method, e.g. if the only issue is that the power is out. The further advantage of this approach is that it would allow depots to be de-electrified, improving safety particularly in third rail areas.

This should be standard spec on brand new EMUs and serious consideration given to retrofit on existing ones as close to that spec as can be achieved.

DMUs are of course different as the diesel engines can provide this and even if one coach has failed the others usually won't have.

 

[Russel]

Thats my view too, people should not need reminding,

At same time SWR advertises that its fleet is air conditioned, and with multiple days over 28c (even to mid to high 30s) should see it as safety to ensure all its trains have it functioning properly so that people dont get caught out by unacceptable temperatures inside.

Agreed, failed air-con on a train with no opening windows isn't acceptable at all once the temperature hits anything above about 25 degrees.

A little bottle of water won't stop them getting sunburnt. An umbrella (parasol) is the obvious answer, as well as having brought some water, but I think this obsession with sipping all the time is wrong. You can have liquid at meals and then work hard in heat and only need a drink at the next break (which might well be sooner in hot conditions.) The body contains lots of water and you can draw it down a long way before refilling afterwards.

That is actually quite an irresponsible suggestion.

 

[Bletchleyite]

That is actually quite an irresponsible suggestion.

It's how people used to do it. It's maybe not medically ideal, but as long as you do take on enough water when you do so (i.e. overhydrate a bit) it's fine.

I will quite happily go out and run 10 miles (though not in this heat, water or otherwise) carrying nothing but keys and phone. The body does store quite a lot of water. As long as you do replenish its stores it can cope fine unless you have a health issue or are elderly or otherwise infirm.

== Doublepost prevention - post automatically merged: 22 Jun 2026 ==

But if the current spec is going to cause a problem in the future given that rolling stock lifetimes can be 30 years then surely not dealing with it is just creating another 'self inflicted' problem.

If the issue is aircon you can replace it. The Chlltern 165 cooling system (not technically aircon I believe as it doesn't reduce moisture levels) is great, and these units didn't have anything to start with. If the likes of 158s are to be used for much longer they will really need to consider it.

 

[Russel]

It's how people used to do it. It's maybe not medically ideal, but as long as you do take on enough water when you do so (i.e. overhydrate a bit) it's fine.

I will quite happily go out and run 10 miles (though not in this heat, water or otherwise) carrying nothing but keys and phone. The body does store quite a lot of water. As long as you do replenish its stores it can cope fine unless you have a health issue or are elderly or otherwise infirm.

I get where you're coming from, but given the accessibility of drinking water and the medical benefits, I'm not sure what good reason there is for not carrying a bottle during a heatwave.

 

[Bletchleyite]

I get where you're coming from, but given the accessibility of drinking water and the medical benefits, I'm not sure what good reason there is for not carrying a bottle during a heatwave.

When running? Because it's a pain. You either have something faffy in your hand or you need a rucksack or vest which reduces your body's ability to radiate heat. I'm very conscious of these things as I tend to overhead badly if I get them wrong.

Normally I do have a bottle in the side of my rucksack, but I don't sip while walking around and don't really feel much of a need to do so.

 

[AndrewE]

Bottled water is safe to drink for years after it's been bottled. There isn't a "high bug load" or anything else in it.

You obviously have never been involved in this in any technical way. Bottled water has an exceptionally lenient bug load limit (compared with tap water) and the test is only valid if it is done within 30 minutes of bottling as the numbers keep ramping up from then on. I can't find the numbers now, but https://www.britishsoftdrinks.com/media/ptiifjc2/bottled_water_guidedec10lr.pdf says lots about what should be tested and when, but gives no limits. Something I found said "Free from coliforms at the time of bottling!"

It should be thrown away after a couple of years as the plastic itself will start to degrade and could leach some chemicals into the water but that's why all bottled water manufacturers print a best before date of around two years post manufacture as after that point the plastic might begin to degrade. But even then the water is still safe (it's a best before not use by). I think we can be sure that it's highly unlikely any bottled water is likely to be sat around for long enough on a train for that to become an issue...

That is very complacent (and, most unusually, I find myself agreeing with the people who normally say that about railway responses to criticism.) You think trains will be de-stocked of the bottled water in September, it all thrown away and then completely restocked next spring? Or that rotation of stocks of bottles in all trains will be diligently done?
And I still think that encouraging the mass provision of stuff in single-use plastic is wrong.

 

[Bletchleyite]

It's also a strength of LNERs that even their electric units have a diesel engine which can power onboard facilities like aircon even when the wires are de-energized. I do wonder if that is also something that should be rolled out a bit more widely (or alternatively batteries capable of doing the job fitted).

I think battery tech is such that a battery capable of 4 hours of HVAC (even in a degraded mode) or low speed movement to the next station is entirely feasible and should be standard in all new stock and retrofitted where possible. I say 4 hours as evacuations invariably seem to take 3.

There are other advantages too, e.g. somewhere to put regen even if the OHLE/third rail isn't able to take it (on the basis that for longevity you'd normally keep the battery around 80%).

 

[ainsworth74]

You obviously have never been involved in this in any technical way.

I was unaware that you were a bottled water engineer so sorry

Bottled water has an exceptionally lenient bug load limit (compared with tap water) and the test is only valid if it is done within 30 minutes of bottling as the numbers keep ramping up from then on. I can't find the numbers now, but https://www.britishsoftdrinks.com/media/ptiifjc2/bottled_water_guidedec10lr.pdf says lots about what should be tested and when, but gives no limits. Something I found said "Free from coliforms at the time of bottling!"

And yet people aren't dropping dead or vomiting all over the place after drinking water from bottles that have been left lying around for months or even years. Indeed there are plenty of countries where drinking the tap water is more dangerous than the bottled water (admittedly we're not one of them!). Point remains. If there was an actual risk from drinking water that had been bottled at a bottling plant after a year or two it would be given a use by date rather than a best before date.

That is very complacent (and, most unusually, I find myself agreeing with the people who normally say that about railway responses to criticism.) You think trains will be de-stocked of the bottled water in September, it all thrown away and then completely restocked next spring? Or that rotation of stocks of bottles in all trains will be diligently done?

I reckon that most trains will get through their stocks of bottled water naturally to be honest. There's enough incidents that happen to cause water to be handed out that the odds of a train keeping the same bottles beyond the best before date of one pallet seems remote. But even if not I have enough faith that someone doing a tick box "Is this water within it's best before date?" is the kind of thing that a rules bound organisation can cope with. After all they manage to keep up with the much more stringent food safety requirements for onboard catering...

And I still think that encouraging the mass provision of stuff in single-use plastic is wrong.

Sure, we should be reducing single use plastic but there are places where it's still useful. Provision of emergency water seems like one of those places where it's the easiest way to achieve the required effect.

And at the end of the day no-one is going to force you to drink the water if you don't want to. But plenty of other people will no doubt find it very beneficial to have access to water if a train is stranded and very hot. Or would you rather people were passing out on this stranded train because we didn't keep any bottled water on hand because of bug loads and excessive single use plastics? I know which I prefer...

I think battery tech is such that a battery capable of 4 hours of HVAC (even in a degraded mode) or low speed movement to the next station is entirely feasible and should be standard in all new stock and retrofitted where possible. I say 4 hours as evacuations invariably seem to take 3.

There are other advantages too, e.g. somewhere to put regen even if the OHLE/third rail isn't able to take it (on the basis that for longevity you'd normally keep the battery around 80%).

Yeah I reckon that battery tech has probably come on far enough now that in reality you'd just sling some batteries under a vehicle or two rather than a diesel engine. But eithe way it should definitely be standard!

 

[AndrewE]

That is actually quite an irresponsible suggestion.

perhaps you would like to read https://www.bohs.org/app/uploads/2024/04/FB.2-M502-Student-Manual-Feb24.pdf ("Student Manual M502: Thermal Environment") which has

3.5.4: Dehydration While sweating is a natural process of the body to control temperature, it presents a problem in that it sacrifices body fluid to cool the skin surface. For people working hard in hot environments the maximum daily sweat rate can approach 10 – 15 litres/day (Taylor 2005) and the resultant dehydration diminishes the effectiveness of blood circulation for distributing heat in the body. Dehydration can lead to the following consequences: • Reduced blood volume • Impaired cardiovascular stability • Reduced physical and cognitive performance • Reduced muscle and general endurance • Elevated thermal strain at any given thermal stress • Reduced heat tolerance • Reduction in the benefits of heat adaption • Increased risk of heat illness Critical thresholds for dehydration as % of body weight, have been defined by Taylor (2005) as: 3% - Physical and cognitive performance starts to deteriorate (occurs in about 45 minutes during heavy work without fluid replacement).

3% of body weight is a water loss that I bet I have never reached - or maybe I did once on the last stage of the Pennine Way with a stupidly heavy load in blistering heat.
You could read some of the reference books or research (not the stuff sponsored by bottled water companies) before judging.

 

[Russel]

perhaps you would like to read https://www.bohs.org/app/uploads/2024/04/FB.2-M502-Student-Manual-Feb24.pdf ("Student Manual M502: Thermal Environment") or some of the reference books or research (not the stuff sponsored by bottled water companies) before judging.

It may be technically safe, but why purposely restrict your water intake?

 

[Bletchleyite]

It may be technically safe, but why purposely restrict your water intake?

It's not sensible to purposely restrict your water intake (i.e. to wilfully become dehydrated*), but there are plenty of circumstances where carrying it is a faff and a healthy adult body is perfectly able to cope with that.

* Though often boxers use it as a tool pre-weigh-in because the body does contain rather a lot of water and so it's an easy way to get into a lower weight category.