Channel Tunnel Problem

[Old Timer]

All this talk of survivability is all rather silly. There have been more deaths, and the risk assessment accepts there will be deaths during the evacuation of the LUL system.

There is an infantisimal chance of deaths occurring through a train failure in the Channel Tunnel and to start down a road to suggest this, as well as introducing "conspiracy" where there is plainly (to the expert eye), been none, is to say the least inappropriate.

All that we need now is for the gutter Press to pick up on this and hey presto more bad Railway news because someone wants to make ill-informed speculation. :roll:

It NOT "....difficult to envisage a scenario where all motors are functioning correctly 10 minutes prior to entering the tunnel and then sufficient fail to disable the train..." The traction motors need an air supply to maintain their temperature within an acceptable range. This is supply by both forced air as well as air entering the power car through the side grills. This is necessary to cope with the high summer temperatures.

To prevent snow entering into this area it is the practice to install protection. This protection has worked very well with the type of snow that has been experienced so far.

Even the French are accepting that the type of snow is somewhat different in texture this year.

In this particular case the snow was able to reach the main transformers and cause problems.

Much has been said about the number of trains in the tunnel. There is nothing unusual in this and it is perfectly permissible, indeed if we worked on the basis of only one train in there at a time, we might as well all go back to using the ships.

Comment has been made as to the length of time that was taken to clear the trains.

Going in to recover a train is a time consuming process and is never done before the Driver has established that there is a complete traction failure.

Having come to a stand the Driver of the first train carried out a series of fault finding procedures before it became apparant that the train was a complete failure. Communications were hampered by the particular situation that exists in the Tunnel and the need for technical advice to be transmitted via third/fourth parties.

During this time subsequent trains started to develop traction and power supply problems.

The rescue locos are intended to rescue "one-off" failures. In this case there were a series of trains that had to be recovered. Unfortunately both lines at one time were blocked.

As I believe someone has already stated, it would be necessary for the assisting locomotive(s) to rectreate the air pressure through the train, as the air within the system will always leak off over time, without the compressors running.

As the trains require a considerable amount of air for the braking system pipes, the individiual bogie brake reservoir cylinders, the air suspension, door operating systems, et al, it took some time before the first train had sufficient air pressure to enable it to be withdrawn. This is an inevitable fact of life.

A "normal" HST/Mk4 set/Pendolino will take some time for the locomotive to recreate the air throughout the whole train from one end, again a fact of life.

In practically all cases of the forseeable failure modes, the battery supplies will be adequate to maintain the environmental conditions on a failed train form a sufficient period to enable the assistance to come from either end of the tunnel. In this case the sheer volume of failed trains extended this time.

The option of using a train on another line to recover passengers is ranked at the lower end of the scale, because in normal circumstances, there Eurostar trains are capable of operating through the tunnel with one power car operational. In less than normal circumstances, the option to split the train is available but is less optimal.

Multiple individual train failures within an area are extremely rare, indeed in my whole service life I have known this only once, indeed I was on shift when it happened. The result was two trains standing side by side, one on the Down Fast and one on the Down Slow.

An EMU had failed on the Down Slow with a F/Liner stood in rear, and a loco hauled Class 1 was stood on the Down Fast with an EMU behind. The outcome was the blockage of the WCML one Christmas Eve for nearly two hours whilst we got assistance arranged. Part of this delay was due to having to blow air into the failed trains.

I use this as an example so that we can get a little perspective into the argument.

There has been much indignation shown on here and much criticism made of the lack of redundancy.

The simple fact is that as a Country we are NOT prepared to pay for this, unlike our Continental cousins. Both I and a Traction Engineer would very easily give you as much redundancy as you want, even to the once in a million year event.

The one thing I guarantee though is that YOU will NOT want to pay the premium that this brings with it.

The sad thing is that those who wail and moan loudest of all, and demand head on plates, are those usually least willing to pay for what they demand.

Over this very same weekend several thousands of people were trapped overnight on the road network in the UK. On Saturday passengers boarded a morning flight at 1600 hours, and were still sat on the plane on the tarmac 12 hours later. Basingstoke appears to have been caught totally unawares by the snow and frost every other part of the Country knew was coming, yet once again it is the Railways who are the target of the Media.

 

[EM2]

OT, I know we have had our differences on here but that ^^^ is a fantastic post.

 

[Old Timer]

OT, I know we have had our differences on here but that ^^^ is a fantastic post.

Thank you, frustration has been building but I have been too busy in the last week or so to sit down and write something more detailed. I did create a post on Saturday but the server went down or did something silly and all that I wrote was lost.

Unfortunately the above is all I can do right now.

We may have our differences, but I would still buy you a pint if we ever met.

 

[Micky Redmire]

All this talk of survivability is all rather silly. There have been more deaths, and the risk assessment accepts there will be deaths during the evacuation of the LUL system.

I regard survivability as an important part of the design process, I'm surprised you don't; as I am sure you are aware(?), UK legislation requires designers to consider risk, one aspect of which is survivability, hence the current focus on protected cores for elderly tower blocks in the UK and hardened protected cores for new construction following the attack on the World Trade Centre. As far as I am aware, no LUL evacuation has even approached the timescale required for the evacuation following the Eurostar incident, but then the logistics are of a different magnitude, so an alternative design approach should be considered.

There is an infantisimal chance of deaths occurring through a train failure in the Channel Tunnel and to start down a road to suggest this, as well as introducing "conspiracy" where there is plainly (to the expert eye), been none, is to say the least inappropriate.

If O2 depletion and increased levels of CO2 were occurring then there was clearly a risk of fatality, particularly amongst those passengers with existing medical issues eg asthma. You need to understand the difference between a conspiracy theory and a conspiracy. Please feel free to research.

All that we need now is for the gutter Press to pick up on this and hey presto more bad Railway news because someone wants to make ill-informed speculation. :roll:

I don't think that anyone involved in British engineering wants bad Railway news, but I also think that the rail industry as a whole has an incompetent approach to PR and passenger information systems, part and parcel of an insular inefficient structure. Ill-informed? If that refers to my postings then feel free to support with detailed comment.

It NOT "....difficult to envisage a scenario where all motors are functioning correctly 10 minutes prior to entering the tunnel and then sufficient fail to disable the train..." The traction motors need an air supply to maintain their temperature within an acceptable range. This is supply by both forced air as well as air entering the power car through the side grills. This is necessary to cope with the high summer temperatures.

To prevent snow entering into this area it is the practice to install protection. This protection has worked very well with the type of snow that has been experienced so far.

Even the French are accepting that the type of snow is somewhat different in texture this year.

In this particular case the snow was able to reach the main transformers and cause problems.

Air cooling is the VE option, but by definition it introduces the risk of foreign objects in close proximity to critical components (snow, motors, transformers). A closed loop liquid cooled circuit eliminates this risk (although increases construction and maintenance costs), I'm sure all this was addressed in the design risk assessment...
Snow is snow, I know there are many different types, but it's still snow. And anyone who attempts to use the "wrong snow" excuse probably has little idea of the bad PR this creates.

Much has been said about the number of trains in the tunnel. There is nothing unusual in this and it is perfectly permissible, indeed if we worked on the basis of only one train in there at a time, we might as well all go back to using the ships.

It appears that both tunnel bores were blocked by UK-bound trains, therefore, the proposed failure mode of multiple VCB disconnections becomes more problematic. If the ratio is 2 failed trains in one tunnel and 3 in the other, then - out of 5 trains - this suggests that 4 suffered dual VCB disconnection. The key issue with regards to the number of trains in each tunnel is: was a train sent into a tunnel which held a failed train?

Comment has been made as to the length of time that was taken to clear the trains.

Going in to recover a train is a time consuming process and is never done before the Driver has established that there is a complete traction failure.

With a comprehensive range of installed sensors and data loggers, I suggest that this should take no more than 15 minutes, are the motors and transformers equipped with moisture detection sensors?

Having come to a stand the Driver of the first train carried out a series of fault finding procedures before it became apparant that the train was a complete failure. Communications were hampered by the particular situation that exists in the Tunnel and the need for technical advice to be transmitted via third/fourth parties.

As above, 15 minutes fault finding maximum, my guess (yes, a guess) is that someone made an assumption that moisture was involved and that this would dissipate over time in the warm environment of the tunnel. What is the particular situation that exists in the tunnel? All data can be read in real-time at remote locations via a network, so no need for the driver to be piggy in the middle.

During this time subsequent trains started to develop traction and power supply problems.

We leads us back to: was a train permitted into a tunnel with a failed train ahead?

The rescue locos are intended to rescue "one-off" failures. In this case there were a series of trains that had to be recovered. Unfortunately both lines at one time were blocked.

This would not stop a recovery locomotive rescuing the first and/or last failed train in each tunnel. Were the recovery locomotives on standby?

As I believe someone has already stated, it would be necessary for the assisting locomotive(s) to rectreate the air pressure through the train, as the air within the system will always leak off over time, without the compressors running.

As the trains require a considerable amount of air for the braking system pipes, the individiual bogie brake reservoir cylinders, the air suspension, door operating systems, et al, it took some time before the first train had sufficient air pressure to enable it to be withdrawn. This is an inevitable fact of life.

We'll fix that with additional, bigger compressors.

A "normal" HST/Mk4 set/Pendolino will take some time for the locomotive to recreate the air throughout the whole train from one end, again a fact of life.

In practically all cases of the forseeable failure modes, the battery supplies will be adequate to maintain the environmental conditions on a failed train form a sufficient period to enable the assistance to come from either end of the tunnel. In this case the sheer volume of failed trains extended this time.

The design risk assessment now requires to be modified to reflect extended entrapment times, the first failed train could have been recovered by a recovery locomotive based at Folkestone within a reasonable timeframe, assuming that the recovery locomotive is based at Folkestone and that the instruction had been given to use it, it's irrelevant how many trains were stuck behind the first failed train.

The option of using a train on another line to recover passengers is ranked at the lower end of the scale, because in normal circumstances, there Eurostar trains are capable of operating through the tunnel with one power car operational. In less than normal circumstances, the option to split the train is available but is less optimal.

One of the key functions of the design risk assessment is to consider abnormal operation.

Multiple individual train failures within an area are extremely rare, indeed in my whole service life I have known this only once, indeed I was on shift when it happened. The result was two trains standing side by side, one on the Down Fast and one on the Down Slow.

An EMU had failed on the Down Slow with a F/Liner stood in rear, and a loco hauled Class 1 was stood on the Down Fast with an EMU behind. The outcome was the blockage of the WCML one Christmas Eve for nearly two hours whilst we got assistance arranged. Part of this delay was due to having to blow air into the failed trains.

I use this as an example so that we can get a little perspective into the argument.

"for nearly two hours" Two hours; again, many emergency lighting systems are designed to operate for two hours. To be trapped for two hours is not good, but it's a lot better than to be trapped for ten or more hours

There has been much indignation shown on here and much criticism made of the lack of redundancy.

The simple fact is that as a Country we are NOT prepared to pay for this, unlike our Continental cousins. Both I and a Traction Engineer would very easily give you as much redundancy as you want, even to the once in a million year event.

The one thing I guarantee though is that YOU will NOT want to pay the premium that this brings with it.

The sad thing is that those who wail and moan loudest of all, and demand head on plates, are those usually least willing to pay for what they demand.

I can't recall prospective passengers ever being asked if they would accept reduced costs for increased risk of extended entrapment. Somewhere in the design risk assessment there will be a statement regarding the maximum entrapment time, this should be compared to the maximum entrapment time during the recent incident. It's a simple as that. If the design risk assessment does not refer to maximum entrapment time and recovery procedures then the designer should be called to account, if it permits extended times then the designer should be required to account for the reported failure of life safety systems. If the recovery procedures were not implemented in compliance with the procedures identified in the design risk assessment then Eurotunnel/Eurostar management should be required to account for their actions.

Over this very same weekend several thousands of people were trapped overnight on the road network in the UK. On Saturday passengers boarded a morning flight at 1600 hours, and were still sat on the plane on the tarmac 12 hours later. Basingstoke appears to have been caught totally unawares by the snow and frost every other part of the Country knew was coming, yet once again it is the Railways who are the target of the Media.

I don't think that people involved in either situation were advised "not to breathe deeply to conserve oxygen", Eurostar's CEO didn't do himself or anyone associated with the crossing any favours with his public utterances.

Merry Christmas!

 

[poshbakerloo]

its shame its all turned out so bad for em!

 

[O L Leigh]

Mickey,

I'm afraid that you are still failing to completely grasp precisely the technical and operational aspects of this incident. I don't doubt that things would be different if such an event was repeated, but I don't believe that you are adding anything that is workable.

Air-cooling of motors and associated traction equipment works well, even with snow screens. I don't believe that an event that has happened once in 15 years is sufficient justification to throw away an efficient and effective system and replace it with a more complicated system that, as you identify, carries penalties in construction and maintenance costs. Whether it creates bad PR or not, the root of the problem is indeed the "wrong type of snow". However, Eurostar have been smart enough not to use this phrase and refer instead to problems with the snow screens. It's just a different way of explaining the same problem.

I'm not entirely sure that there were multiple VCB openings but, if the snow had affected the transformers, then this would have the same effect and would indeed open the VCB. However, burnt out motors would not necessarily mean that the train couldn't have sat there with the VCB closed and still draw power for all the other systems.

If snow had caused the motors to burn out, have a moisture detection device would be of no help to the driver. All he/she wants to know is whether or not the motors are working. Such a device would only assist the depot staff.

Your 15 minutes of fault-finding is unrealistically short. My company has a 10 minute "cut and run" policy in the peak, but I drive much simpler trains that are much shorter in length. It may indeed only take the driver 15 minutes to identify which system has developed a fault, but it would take much longer than that to establish that the train is a total failure and cannot be moved under it's own power. It's very likely that it would take the driver that long just to walk from the front of the train to the rear power car and back again, and that's without doing anything else.

Allowing more than one train into the tunnel at any one time is normal practice, even when one has failed. It is very simplistic to say that one went in and failed to be followed by the next which in turn failed and so on, and that more and more trains were sent in behind an already large number of failures. It is likely that the time-line of failures was much more complex than that and that perhaps some of the sets which eventually failed did so while waiting behind one that already had.

I can say from experience that it is not a quick matter to declare a train a total failure. Notwithstanding any "cut and run" policy that puts a clock on your fault-finding, it would take a little while between the first signs of a set being unwell and it being declared a failure. For a start, an effort would need to be made in order to determine the nature and severity of the fault, together with some effort being made to rectify the faults to permit the train to be moved. With a train of the size and complexity of a Eurostar I would expect this to take quite some time to complete before the train could be declared a failure. By the time this has all been done, you're going to get a queue of waiting trains forming behind you, one of which the controllers would be hoping to use to assist the failure clear of the pipe. The nature of the failures would still need to be properly understood in order to know what assistance procedure would be appropriate. All of this takes time.

Fitting bigger compressors would not help to "blow up" a failed train any faster. The limit is not the capacity of the compressors but the diameter of the pipes and the sheer volume of air that needs to be provided. Yes you could fit wider diameter pipes, but as an engineer I'm sure you can see the problems inherent in that.

O L Leigh

 

[Old Timer]

I regard survivability as an important part of the design process, I'm surprised you don't; as I am sure you are aware(?), UK legislation requires designers to consider risk, one aspect of which is survivability, hence the current focus on protected cores for elderly tower blocks in the UK and hardened protected cores for new construction following the attack on the World Trade Centre. As far as I am aware, no LUL evacuation has even approached the timescale required for the evacuation following the Eurostar incident, but then the logistics are of a different magnitude, so an alternative design approach should be considered.

Survivability is not and never was an issue in this case, even the Media have not gone down this road. All we have are one or two people who have almost certainly over-emphasised something.

We all know that there are really dramatic stories painted by people in such situations and seized upon by the Media as a means of cynically selling more papers/attracting more viewers. Interestingly enough, even the Media don’t think survivability was an issue. When the facts are probed of course theses “facts” and “experiences” turn out to be so much different.

Only you seem to want to develop an issue out of it, with comments such as :-

Were the passengers really told not to breathe deeply to conserve oxygen? If this was an issue then CEO for E* should be sacked immediately with no compensation.

and

From the information available, if O2 was being depleted and CO2 levels were increasing i.e. "don't breathe too deeply" then - clearly - there was a substantial risk to passengers. Entrapment in confined conditions for long periods is demonstrably survivable for those with the correct training, primarily military, but the general public cannot be expected to react in a similar manner.

Did you think about the logic of that statement before writing it ?

The CT has high powered ventilation systems that are designed to remove smoke and provide clean air. The ventilation system itself is designed so that air is dispersed from the main tunnels through the system, thus self ventilating.
A visit to the London Underground will demonstrate this effect.


You then introduce this debate about “survivability” and “life safety systems”. Why and for what purpose ?

There never was any risk to life and limb at all. Granted that it would eventually have become uncomfortable, but there is a very large difference between being uncomfortable and being in a life threatening situation. No passenger was in a life threatening situation and it is a shame that you continue to peddle this element when it is not relevant.

For example :-

In view of the extended entrapment, step 1 should be to install connection points throughout the tunnels (with secondary supply) to allow the "on-train" services (lighting, aircon, communication etc) to remain live.

In another post you say :-

Of course, where there's AC there is the opportunity for induction, but my preference would be for a separate cable system in the tunnel with connection points available to sustain life safety systems for "dead" stationary trains, this would also enable survivability if general catastrophic mechanical failure of the overhead lines occurred.

In yet another you say :-

Install sufficient secondary power supplies, food, water medical equipment etc to enable 7 fully laden failed sets to maintain a comfortable environment for 24 hours and a survivable environment for 60 hours.

Let us examine these statements a little closer.

Firstly how far apart are you going to place these sockets ? What voltages are you going to use ? What amperage ? Different trains have different voltage requirements for their on-board systems. Where are you going to plug them in ? How do you arrange the circuits. What type of plugs do you use ? the doors and some other services are operated by air, so may we need high pressure air lines as well ?

How do you identify the various different types and their uses ? How do you provide the electrical feed ? How do you tackle the risk of cable faults, possible even leading to fires ?

The power demand would require a HV distribution system, which would also need to be sectioned so that there was sufficient protected system arrangements that a single failure did not lose the supply to an entire train.

So then what about that section of train ? Another opportunity to criticise ?

All these various cabled systems and sockets would all need to be individually tested and certificated on a regular basis to satisfy you otherwise you would be there to criticise. When would this be done ? How long would it take ? How many staff would it take ? The tunnel would need to be shut down whilst this was being done ? What happens if you had a failure of one circuit ? Shut down the tunnel ? after all the event is now foreseeable.

What about the trailing cables ? what would you do if you needed to evacuate ? Would you let people walk over them with a tripping risk ? another opportunity for someone to criticise, or would you require them all to be removed first ? yet another area for potential criticism.

As to food. What sort of food ? how would you cook it ? how would you keep it cool with no electricity. Where would you store all the water ? how would you keep it sterile ? How would ypou proportion food for allergy sufferers ?

Take another comment :

The element I was uncertain about was the means to supply life safety systems eg lighting, ventilation. My understanding is that the fault protection for the traction motor circuit can also disconnect the life safety system, my suggestion is that this should not occur, my proposal is that either the life safety system has a dedicated connection to the pantograph, so irrespective of any fault conditions affecting the traction circuit, lighting and ventilation are still effective; or the life safety system can utilise a secondary pantograph in a static situation, the traction circuit can disconnect, the primary pantograph can disconnect but the passenger environment remains as per design. This should eliminate the reported lack of lighting and ventilation.

The passenger environmental systems are designed to run for several hours, certainly sufficiently long to deal with all previously foreseeable incidents.

If you want another pantograph and duplicated power supply system then fine, but this will lead to the loss of one vehicle through the need to duplicate this at each side, and of course it would need to be separated entirely from the main transformer room.

Such a system would need considerable modifications to the wiring and control circuits of the trains, and would require sets to be taken out of use whilst this was done.

Maintenance requirements would increase as would the testing requirements. Spares for all this equipment would be needed, even though it is unlikely ever to be used again.

And what if a fault develops ? take the train out of service ? put everyone onto a following packed train ? Passengers standing? Of course then there could be no hot drinks taken down the train by the staff – H&S requirements but another area for criticism.

This of course all falls down if there is a problem with the traction current supply.

Lets move onto the traction current supply :-

Operating electrical equipment in hostile environments is far from specific to the Chunnel, submarines for example. Inspection and testing should be occurring for health and safety issues at the very least, but also to verify maintenance procedures and to attempt to ensure that the things don't breakdown, this is all basic stuff!

It may be for you but actually all the electrical systems in a submarine are contained with a controlled dry temperature environment, unlike the tunnel. They have moved on a bit since Das Boot.

Regarding HV insulators, if dampness is a problem then the arc struck should vaporise the water, problem fixed; this may or may not result in a protective device functioning. If repeated disconnection occurs then duplicate that part of the circuit. Nothing new here, it's been standard practice for decades, but the problems arise when value engineering occurs (or incompetence) and sufficient redundancy is not included within the final design. Up until a couple of days ago, the general travelling public didn't perceive this as a problem, but now they do.

The above appears to indicate a lack of understanding of HV transmission systems and certainly railway OHL systems.

Firstly insulators are designed to insulate, and are designed so that any water running onto the insulator is broken in such a way as to prevent a flashover. A flashover on a porcelain or ceramic insulator often leads to the insulator “exploding” or at least sustaining damaged vanes. Polymeric insulators tend to suffer from flash-over heat damage. As I said the whole point of an insulator is to prevent flashover.

You talk of redundancy. This suggests a duplicated system. If there is a problem which causes one insulator to fail then it is likely that it will affect an adjoining insulator in the close vicinity.

These duplicated systems. Would they be independent or duplicated ?

If they are independent then there is the various issues that arise from induction. In any case how do you separate the tow contact wires ? You cannot separate by height.

But assuming that we could develop such a system (which no-one else in the world deems necessary by the way, including the new Gothard Tunnel) you have just doubled the infrastructure costs, will require more than twice the amount of time needed for maintenance and inspection, as well as having to provide duplicated control and monitoring systems.

For true redundancy the system would require separate feeding from an independent incoming NG supply, and this brings with it issue to do with phase separation, as well as the complexity of control interlocking.
What do you do if the second supply develops a fault ? shut down the train service ?


You made the following comment :-

LU construction/maintenance specifications and contract conditions are rigorous to say the least, probably 3rd in the hierarchy after nuclear and petrochem in the field I'm in, the contract costs reflect this. Sadly, the business case generally follows after a fatality, Kings Cross being a prime example.

We are all too well aware of LUL Standards, and the costs that they impose. That is why a single ticket between two stations that you can walk between quicker is £4.50.

Look at some of these Standards. Why is it necessary for doors to have two-hour fire separation when the response time of the fire brigade is measured in less than 5 minutes, by which time the station has been evacuated ? These doors are hideously expensive yet are totally unnecessary. Many of the safety procedures that LUL operate are the result of the knee-jerk reaction to Kings Cross where people (such as yourself no doubt) were quick to come up with a whole variety of “must be dones”.

I would contend that knee-jerk responses to safety incidents actually do great damage in the long term as do the uninformed media commentaries that are designed to reduce complex issues to mere soundbites simply to enable the generation of greater sales revenue.

The outcome of Clapham was to cause the Industry to actually become less safe in the longer term , and taking TPWS into account, RSSB research has already demonstrated that there will be more deaths to trackside maintenance staff than to passengers as a result of having this system.

..I don't think that anyone involved in British engineering wants bad Railway news, but I also think that the rail industry as a whole has an incompetent approach to PR and passenger information systems, part and parcel of an insular inefficient structure. Ill-informed? If that refers to my postings then feel free to support with detailed comment.

I have done.

I presume you will be happy of the CT now resorts to reducing the capacity for he whole system to the number of trains that can be recovered in a timeline acceptable to you. That is a maximum of two trains only in each tunnel at a time, after all we cannot assume any more that the train can be driven in reverse or driven forward from the rear cab

The procedure for the recovery of the trains as set out did work. All these things take time to set up.

In another post you said :-

Procure sufficient locomotives to haul 7 dead sets out of one tunnel, these locomotives to be on permanent standby, with, say, 4 additional out of service undergoing maintenance.

Please explain how these locomotives can reach trains trapped in between the leading/trailing failures. The maximum you would need would be four and from experience this is probably over the top anyway. Still never mind it can be covered by higher fares.

As above, 15 minutes fault finding maximum, my guess (yes, a guess) is that someone made an assumption that moisture was involved and that this would dissipate over time in the warm environment of the tunnel. What is the particular situation that exists in the tunnel? All data can be read in real-time at remote locations via a network, so no need for the driver to be piggy in the middle.

A guess but quite wrong. There is a process for fault identification to ensure that the process addresses all fault scenarios. It is quite wrong to suggest that the Driver or anyone else would make the connection so quickly, indeed if that was the case why was there extensive running tests with engineers and monitoring equipment on board to establish the cause of the failure. It is not finally concluded that moisture WAS wholly responsible, this suggestion having been thrown into the ring by a variety of people commenting without any obvious underlying experience or knowledge upon which to base their assertions.

Similar types of comments were made following the Air France AF447 loss, yet were subsequently found to have been wide of the mark.

We leads us back to: was a train permitted into a tunnel with a failed train ahead?

You have evidence to demonstrate that this was the case ? You are able to specifically state that the trains were not running in close succession ?

This would not stop a recovery locomotive rescuing the first and/or last failed train in each tunnel. Were the recovery locomotives on standby?

The recovery locomotive was obviously on standby, but trains preventing access to the failure needed to be cleared.

We'll fix that with additional, bigger compressors.

Again demonstrating a lack of understanding of railway system. The air system is rated to a specific pressure. Firstly large compressors do not assist if this pressure is exceed, secondly the amount of air that can be blown into the train depends upon the size of the pipework.

The design risk assessment now requires to be modified to reflect extended entrapment times, the first failed train could have been recovered by a recovery locomotive based at Folkestone within a reasonable timeframe, assuming that the recovery locomotive is based at Folkestone and that the instruction had been given to use it, it's irrelevant how many trains were stuck behind the first failed train.

One of the key functions of the design risk assessment is to consider abnormal operation.
"for nearly two hours" Two hours; again, many emergency lighting systems are designed to operate for two hours. To be trapped for two hours is not good, but it's a lot better than to be trapped for ten or more hours

The current arrangements are adequate to cover all reasonably foreseeable incidents. Risk assessment requires that risks are “reasonably” mitigated. Those risks were and are.

The Inquiry will reach a judgement as to whether arrangements above and beyond that are judged to be appropriate. I for one shall not be holding my breath.

Certainly the fact that no Regulatory authority is rushing around with Prohibition Orders and Improvement Notices, let alone proposing to investigate is a pretty good indicator as to what view the various safety specialists take.

I can't recall prospective passengers ever being asked if they would accept reduced costs for increased risk of extended entrapment. Somewhere in the design risk assessment there will be a statement regarding the maximum entrapment time, this should be compared to the maximum entrapment time during the recent incident. It's a simple as that.

The whole variety of systems that you want implemented will take the cost of existing fares up by a good factor, probably three or four times.

The CT and its users are competing against ferries and cut price airlines, and the fact that passengers already have to be offered cheap tickets answers your own question.

In any case lets do a little simple statistical calculation. If you undertook two round trips every day for the last 15 years you would have taken 21,916 journeys (365 x 2 x 2 x 15+(4 x 2 x 2). Taking the fact that 5 trains failed, this gives you a very simple back of the envelope risk of one journey in every 4383 resulting in the scenario that existed at the weekend.

I suggest you run a poll and ask people if they would pay a fare in the magnitude of say four times what it is now in order NOT to be involved in an extended delay in the CT, of which is likely to be a 1 in 4383 chance of it happening. Now this is the absolute minimum as it is suggested that weather of this nature is perhaps a once in 20 year occurrence, that suggests a 1 in 87,660 risk.

I rather think I know the answer to that one already.

You need to understand the difference between a conspiracy theory and a conspiracy. Please feel free to research. .

For your benefit I did.

West’s Encyclopedia of American Law defines a “Conspiracy” thus :
An agreement to perform together an illegal, wrongful, or subversive act.

The Merriam-Webster Dictionary defines “Conspiracy Theory” as An agreement to perform together an illegal, wrongful, or subversive act.

May I suggest you do a little research into Railways ?

 

[royaloak]

Well done OT, I wouldn't have bothered, he obviously hasn't got a clue how long the channel tunnels are or any understanding about engineering.

 

[ukrob]

Huge respect to you OT for that post. I gave up with him long ago in this thread

 

[eurostarclient]

I am a Eurostar client, a very frequent traveller on the Paris-London route.

Thank you so much for the debate so far. You guys do have an audience.

I am much more interested in understanding the rescue procedure/communication issue for my future peace of mind, as I am sure the technical issue will be solved. I have taken facts from this forum in particular thanks to boing_uk, O_L_Leigh, captainbigun, EM2 and 91101, other forums and people I know who were there.

Here is my recap of what happened (again - I am not discussing the technical root problem, just the process). Any further fact finding will be appreciated.

1. If one Eurostar fails in the tunnel, another train can be allowed in because they would have the potential to help.

2. Eurostar trains travel in "flights" of 3 trains relatively close to each other. When the first train failed in the South tunnel, the second and third had also probably just entered the same tunnel and stopped behind the first. At some point they also failed.

3. It is Eurotunnel (not Eurostar) who controls when and how many trains can enter the tunnel.

4. It is likely that ET thought the 2nd and 3rd train just stopped because the 1st had failed and not because of an "epidemic" issue. So the 4th and 5th have been rerouted to the North tunnel, and they both failed in there.

5. It takes time (30-60mins?) to fully investigate what's wrong and declare that a train has failed and needs to be towed away.

6. High voltage 25kV needs to be turned off to allow maintenance teams to operate safely.

7. The standard procedure would be that one Eurostar could push/pull another one to the exit. But with all sets failed, this was not possible. Most likely, 25kV supply also was off.

8. In this case ET uses diesel locomotives as rescue engines. Not any diesel locomotive is allowed in the tunnel, it has to be a specially modified because of the exhaust emissions. ET has 5 of these standing by for rescue purposes. Here is a photo: http://www.rtranmer.fotopic.net/p62576835.html

9. Connecting a Eurostar train to a standard locomotive requires a special connection kit that needs to be assembled to make an emergency coupler. This also requires more time. (any idea?).

10. All trains have onboard auxiliary batteries to provide emergency lighting and communication for several (?) hours. The batteries are also used to open/close doors. It would be extremely dangerous to let passengers out inside the tunnel at any time so doors have to remain shut, but they could be opened in case of fire.

11. Once a locomotive is connected, it takes time to pump air in the Eurostar. Pumped air is required to operate a number of parts (doors for ex) and in particular, brakes.

12. The tunnel is not flat, it's shaped like a U. There is a gradient at all sections. So in order not to have all trains roll down in the middle section they had to put full brakes on. Once brakes are set, they cannot not be removed without power supply to pump air in.

So the whole operation has basically taken a lot of time.

13. The tunnel has a ventilation systems that is designed to remove smoke and provide clean air. The ventilation system itself is designed so that air is dispersed from the main
tunnels through the system, thus self ventilating. Thus, CO2 intoxication has never been a realistic scenario.

14. Eurostar HQ cannot talk to their staff inside the trains. Eurostar staff during emergency operations inside the tunnel is in exclusive contact with Eurotunnel staff.
At the same time, Eurotunnel is not in charge of communicating with passengers.

For some obscure reason during the operation there has been mininal communication to passengers. Even Eurostar staff seemed to be in the dark and very stressed. This has created usless stress and frustration but there has never been a risk of death.

One piece of information I cannot explain: some passengers have reported hearing a big "bang" in the dark. Any clue?

 

[yorkie]

Now I see why the bowing/nodding guy was moaning at it being a "death trap" and that they were treated like "animals". He probably expected this http://www.dailymail.co.uk/news/art...-John-Lewis-bed-department-stranded-snow.html !

Disgraceful isn't it? Eurostar should, clearly, have an underground bunker with 2,500 beds available on demand for an event like this so that customers can be treated like they were in John Lewis' and not like animals. 500 toilets should be provided. Hot & cold water for all should be available. It doesn't matter if it costs a few billion, it needs to be done otherwise the bowing guy will get angry.

 

[Old Timer]

Cheap fares brings you this type of people.

 

[Vulcan]

The bowing/nodding man made me laugh. Its a 'death trap', which explains why he is standing there alive and well. :-/

 

[Old Timer]

He's going to dine out on that story for years, and at each telling it will get more and more like Singapore in 1942.

I bet one of the reptilian claims solicitors are wetting their pants at the thought of taking his "stress" claim through the Courts. My money says he will milk this for all it's worth.

Unfortunately these people are incapable of understanding that by over-dramatising, they damage the legitimacy of all of their claims, even accepting that some of them are true.

I can certainly see the French Crews just shrugging their shoulders. My limited experience with them has seen this a number of times. It is all down to the French management style which is the opposite to that of the UK, where the French hierarchy is based on an autocratic method of command and control. Your boss can never be wrong, and even if he is he is still right. This destroys all initiative and explains WW1 and WW2

The result is that the front line staff will just simply wait like sheep to be told what to do, so I can well think that Mr Nodding Donkey is right on that one but his credibility by now of course is damaged.

 

[O L Leigh]

I am a Eurostar client, a very frequent traveller on the Paris-London route.

Thank you so much for the debate so far. You guys do have an audience.

You're most welcome. Sadly these are issues that seem to be beyond the understanding of the media, hence the slightly skewed reporting and oversimplification of the issues.

Incidentally, what audience is this? Is this discussion being linked to more widely; for example, onto another website or forum?

Here is my recap of what happened (again - I am not discussing the technical root problem, just the process). Any further fact finding will be appreciated.

You're almost there with pretty much everything. However, just to satisfy my pedant's desire for completeness (and to increase your understanding) I have added just one or two very minor corrections.

5. It takes time (30-60mins?) to fully investigate what's wrong and declare that a train has failed and needs to be towed away.

The precise length of time between a train coming to a stand and being declared a total failure will depend on a number of factors.

It may be that, like the company I work for, Eurostar have their own "cut and run" policy that limits the amount of time a driver has for fault-finding. However, this only helps in the event that a train can still be moved by operating one or other of the safety bypass switches. It sounds like this was not possible in this event because the failures were major in nature and no amount of bypass switches was going to get these trains moving again.

6. High voltage 25kV needs to be turned off to allow maintenance teams to operate safely.

Not generally, no.

An isolation would be required for maintenance of the tunnel or of the overhead line equipment, but in the event that a train fails in the tunnel an isolation would not be necessary. The overhead power lines are far enough away to pose no risk to life for any member of crew working on the outside of the train.

7. The standard procedure would be that one Eurostar could push/pull another one to the exit. But with all sets failed, this was not possible. Most likely, 25kV supply also was off.

See above.

The problems with Eurostar sets offering assistance is that it is a "one for one" system. Where you have perhaps one functioning set and three failed sets ahead, the functioning set's ability to lend assistance is limited. It could push the hindmost of the three failed sets, but it would still need the other two moved out of the way first.

9. Connecting a Eurostar train to a standard locomotive requires a special connection kit that needs to be assembled to make an emergency coupler. This also requires more time. (any idea?).

No idea on times. The photos linked to earlier show that the emergency coupler adapter is in kit form with rather a large number of pieces. Just moving the pieces to the appropriate end and assembling them correctly would take a reasonable amount of time.

However, all the rescue locos cleared for use in the tunnel already have a compatible coupler mounted to each end to speed the rescue operation along.

10. All trains have onboard auxiliary batteries to provide emergency lighting and communication for several (?) hours. The batteries are also used to open/close doors. It would be extremely dangerous to let passengers out inside the tunnel at any time so doors have to remain shut, but they could be opened in case of fire.

Not the doors, I expect. These would have manual emergency release handles in case of a full power failure.

However, you are correct that the safest place to be is on the train unless, for example, the train no longer represents a safe haven (e.g. because it's on fire).

12. The tunnel is not flat, it's shaped like a U. There is a gradient at all sections. So in order not to have all trains roll down in the middle section they had to put full brakes on. Once brakes are set, they cannot not be removed without power supply to pump air in.

Actually it's more like a "W" shape as the geology under the Channel is this shape with a modest mid-Channel ridge. The idea is that the tunnel would follow a particular chalk stratum that offered the best compromise between stability, water permeability and ease of tunnelling.

14. Eurostar HQ cannot talk to their staff inside the trains. Eurostar staff during emergency operations inside the tunnel is in exclusive contact with Eurotunnel staff.
At the same time, Eurotunnel is not in charge of communicating with passengers.

I expect that Eurostar and Eurotunnel controllers work very closely and that communication between Eurostar traincrew and their controllers was not that difficult. However, all decisions would have been made by Eurotunnel. Communication with passengers would have been via the traincrew.

For some obscure reason during the operation there has been mininal communication to passengers. Even Eurostar staff seemed to be in the dark and very stressed. This has created usless stress and frustration but there has never been a risk of death.

It's not a very obscure reason.

The problem is that Eurostar clearly were not in total control of the situation because it was happening inside the tunnel and, therefore, outside of their direct jurisdiction, and were having to react as the situation changed as more trains failed.

When you're a controller you somtimes find that things change more quickly than you can deal with. For example, if the second Eurostar was meant to assist the first failure out of the tunnel as per usual operating procedures, you don't think there's much of a problem. However, when the set you had earmarked to provide assistance then itself becomes a total failure the situation has escalated. How do you then deal with the original failure? You pull a few moves to keep things moving as best as you can, but as more and more trains fail the situation becomes harder to manage. Suddenly you've got five failed in the pipe and you need to get them out somehow.

From the traincrew's perspective there is such a thing as giving too much information. When explaining an out-of-course incident you need to be realistic about timeframes but without being specific. I know from experience that you can get caught out when you forget this. When it all goes up the wall we are reliant on others to tell us what is happening and what is being done to sort it out, so it's no surprise that Eurostar staff seemed unaware and unhelpful. They probably didn't know precisely what was happening themselves and had to manage the expectations of passengers. It's not an easy position to be in.

One piece of information I cannot explain: some passengers have reported hearing a big "bang" in the dark. Any clue?

It could have been a "flashover".

Basically a flashover is when the power takes a short-cut to earth. When the power happens to be at 25kV AC and with enough amps to push several Eurostars and heavy vehicle Shuttles the resultant "bang" is going to be very loud, especially in the enclosed space of the tunnel.

O L Leigh

 

[eurostarclient]

Incidentally, what audience is this? Is this discussion being linked to more widely; for example, onto another website or forum?

Not that I know, but I came here because someone else posted a link to this forum on Twitter. If I get to the end of the story I will probably post the final understanding on my blog (eurostarclient.com).

An isolation would be required for maintenance of the tunnel or of the overhead line equipment, but in the event that a train fails in the tunnel an isolation would not be necessary.

I assumed the power supply had been switched off given the reports of people left in the dark for hours, and I assumed it was off for safety. But you are right, I am not certain it was off.

However, all the rescue locos cleared for use in the tunnel already have a compatible coupler mounted to each end to speed the rescue operation along.

In this case there is no time lost to mount the couplers.

It could have been a "flashover".

I can figure this is like a classic lightning during thunderstorms. What could have caused this inside the tunnel? And could this be a reason to switch off the supply (as per above assumption?). Here are the exact words:
"We were in the tunnel, about 10 minutes from UK, when we heard this almighty bang. At first, we thought it was a bomb or something it sounded like an explosion or that the train had derailed. Then we were just left there. People got frustrated and they were even charging for water. We were forced to wait in the dark for two hours before being told to evacuate."

 

[O L Leigh]

I assumed the power supply had been switched off given the reports of people left in the dark for hours, and I assumed it was off for safety. But you are right, I am not certain it was off.

Ah no. That could have been because the VCB had opened and could not be closed again. Check back through my more recent posts in this topic and you will find plenty of reference to this.

However, it has been suggested that some or all of the failed trains had problems with the main transformers which step the 25kV AC from the overhead power supply down to the various voltages required by the on-train systems. If this had been knocked out then the train effectively has no connection to the overhead power supply.

I can figure this is like a classic lightning during thunderstorms. What could have caused this inside the tunnel? And could this be a reason to switch off the supply (as per above assumption?). Here are the exact words:
"We were in the tunnel, about 10 minutes from UK, when we heard this almighty bang. At first, we thought it was a bomb or something it sounded like an explosion or that the train had derailed. Then we were just left there. People got frustrated and they were even charging for water. We were forced to wait in the dark for two hours before being told to evacuate."

Flashovers could be caused by any number of things from atmospheric conditions inside the tunnel to a fault on the train or the overhead power supply.

It is possible that a flashover could have caused the circuit breakers on the supply to have tripped but again it would depend on the precise nature of the fault. A flashover is a fleeting effect like a lightning strike so it may not have affected the overheads at all. However, it can cause an overload on the train which will result in a safety cut-out popping.

I have to confess that I am slightly hesitant about taking brief non-expert witness testimony on face value and trying to diagnose faults and likely conditions from them. At the very least, any electric train disconnected from the outside power supply due to a fault or some other cause will still maintain emergency lighting from the on-board batteries, and Eurostar will be no different in this respect. The only exception to this being if the batteries are also tripped due to a fault. However, the level of emergency lighting is MUCH lower than the normal saloon lighting. The correspondent you quote would need to be questioned more closely about the on-board conditions to ascertain precisely what the situation was.

O L Leigh

 

[jon0844]

Eurotunnel is hitting back today, casting blame on Eurostar and saying passengers were bringing all their luggage off the trains too!

 

[Lampshade]

Were the passengers told not to? What else were they supposed to do, participate in the Battle of St Pancras as the crowd rushes and fights for their luggage?

Can't see Eurotunnel convincing anyone with that.

On a lighter note, Merry Christmas

 

[SWT Driver]

The link to the news item: http://news.bbc.co.uk/1/hi/uk/8430596.stm

 

[Dai.]

it's fun watching eurostar and eurotunnel pass the blame.


Alstoms up next I reckon.

 

[yorkie]

Here is the Eurotunnel statement in full:

INFORMATION CONCERNING THE EVENTS OF 18 DECEMBER 2009

Our customer, Eurostar has been in an unprecedented crisis since
18 December and has attracted a great deal of media interest.
Their service was suspended for several days and on Christmas
Eve, only 37 trains, out of the normal 50 that would have been
in service, were operational (24 trains on 23 December, 5 days
after their breakdowns).

Despite the fact that Eurotunnel is clearly not to blame for
these failures, nor responsible for Eurostar?s customer service,
and that our teams intervened with speed and professionalism,
above and beyond what is strictly required, we have been
unfairly criticized for not having reacted correctly. Eurotunnel
will not accept these accusations and, without wanting to become
embroiled in an argument, we would like to present you with the
facts relating to the rescue operations conducted by Eurotunnel
overnight from 18-19 December:

· Five Eurostar trains broke down, one after another,
due to the snow and blocked the two railway tunnels;

· To deal with this kind of incident, Eurotunnel has,
according to the Concession Agreement, two breakdown units (one
for each tunnel);

· These were immediately deployed: (i) the first
Eurostar broke down at 20:53 (CET) and was towed without
incident to London, at the request of Eurostar, (ii) the second
Eurostar broke down at 22:38 and the second rescue unit was sent
to the site, but was blocked by the third Eurostar which broke
down at 23:10;

· The two other Eurostars in the Tunnel were instructed
to transfer to the opposite tunnel, but they both broke down.
One at 00:51 and the other at 00:55;

· The second rescue unit completed its mission, towing
Eurostars 9055 and 9059 to Fokestone;

· Although they were in constant contact with our teams,
it is apparent that the on board Eurostar crews did not relay
any useful information to their passengers. This led to concerns
on board Eurostar 9057 which led to us taking the decision to
evacuate the passengers immediately into the service tunnel in
order to maintain safety. It was also the case that this
Eurostar could not be towed, as the protective cover over the
front coupling on the train could not be opened.

· In this unprecedented emergency event, Eurotunnel sent
one of its own Shuttles which, clearly is not equipped as a
passenger train, to complete the essential mission of rescuing
those people. The time taken to complete this rescue were
unfortunately protracted as the Eurostar crew, in total
disregard of safety procedures, told the passengers to bring
their luggage with them;

· It was also decided to evacuate the last Eurostar to
break down, despite a further complication linked to its
position at an intersection between the two running tunnels
(Cross-over), meaning that the service tunnel passes beneath the
running tunnels, rather than being on the same level;

· All of the people evacuated were repatriated to
Folkestone where they were to be taken back into the care of
Eurostar;

· Kent police conducted a series of incomprehensible and
interminable checks and controls. The two Eurostar trains sent
from London to recover their rescued passengers arrived, very
late, with no food or water on board and with no crew. Several
of the crew members of the evacuated Eurostars were at this time
complaining that they needed to be relieved. All of this caused
further delay, again beyond our control, but nonetheless
unacceptable and therefore the source of lively protest;

· The Eurotunnel staff who were at this time managing
our own customers, who were themselves trapped on the terminal
due to the tunnels being occupied by broken down Eurostars
(several thousand people) - our Shuttle Services being suspended
until 05:30 - decided spontaneously to go to the assistance of
the Eurostar passengers and did everything they could to make
up for the major deficiencies those passengers were
experiencing;

In total, the passengers on board Eurostars 9057 and 9053 exited
the Tunnel about 5 hours after their trains broke down, a very
long time and something that we regret sincerely, but somewhat
less than the 16-17 hours quoted by some commentators who have
confused the journey through the Tunnel with the total journey
time from station to station.

Access to the Tunnel was refused to the last Eurostars in
service. They passed the night at Frethun, instead of returning
to Lille or Paris

It remains just to underline that all the rescue operations were
controlled, from 00:40 by the two states (under the BINAT
agreement). As far as communication between the Eurotunnel
Incident Control Centre and the trains, questioned erroneously
by some, it was continuous: the proof is that if this had not
been the case, the highly complicated rescue operations would
not have been achieved in complete safety;

From the morning following this crisis, Eurotunnel put to
Eurostar a number of measures designed to improve the speed and
comfort of evacuations: notably the provision, by Eurostar or
its shareholders, of a third rescue unit and a passenger train
to conduct evacuations under better conditions than in our car
carrying shuttles.

In parallel, Eurostar, in order to understand what happened, has
appointed two experts, wrongly called an Independent Enquiry
Commission (because they are not independent, nor are they an
Enquiry Commission in the sense of the Concession because there
is no reason at all why their mission should be uniquely focused
on the Tunnel).

Together, Eurotunnel and Eurostar have, over the past 15 years,
become indispensable in linking the Continent and Great Britain.
Eurotunnel will do all in its power to enable Eurostar to get
over this crisis as soon as possible.

 

[Old Timer]

Thank you for that link Yorkie, which backs up pretty much all of what the professionals have either said or hinted as being the case all along.

It certainly puts some of the more dramatic and hysterical posts into true context.

 

[jon0844]

Fascinating stuff. I am sure Eurostar will be able to work professionally with Eurotunnel from now on!! Normally, you'd expect some form of unity in a situation like this - so I suspect Eurostar are going to be in for a lot worse!

Stuff like this is bound to speed up services being introduced by other operators.

 

[EM2]

Stuff like this is bound to speed up services being introduced by other operators.

I dunno, if they think Eurotunnel are going to sling the mud like this, they might decide against it!

 

[A60K]

If this statement by Eurotunnel is essentially correct, then Eurostar's train and incident management staff selection and/or training for emergency procedures would need a thorough shake up.

The bit about a rescue passenger train is interesting - until now it's always been the plan to evacuate to another service train, or if that's not possible then by the service tunnel vehicle fleet. Is ET suggesting a Eurostar set be kept manned on hot standby at one of the tunnel terminals, or a dedicated diesel powered basic train?

 

[Old Timer]

No Eurotunnel's argument is quite simple.

The Eurostar crews refused to work forward on the basis of their duty hours being expired.

Replacement ECS sets were sent to Eurotunnel to collect the passengers but as stated the Eurostar crews would not work them forward. I have a sneaking suspicion this will turn out to be the non-UK crews.

Eurtunnel is not a passenger operator in that sense and has no rolling stock or facilities that will allow passengers to be taken forward. That indeed is the responsibility of Eurostar.

My experience of "foreign" staff in some Countries that are heavily unionised and have regulated hours, is that the staff just simply switch off at the end of their hours and refuse to assist or take part in any role. There is a very clear difference in Cultures here which I have no doubt will hit the light in due course.

 

[whoosh]

UK Eurostar drivers were on strike that day (over the fact that expenses paid to them have fallen in real terms due to the fall of the pound against the euro), so the company had no UK drivers it could call on to assist with this situation.
Because of this strike, I can see the foreign drivers not wanting to be particularly helpful with regard to working extra hours.
Eurostar seem to have a lot of problems at the moment - angry staff, angry passengers, angry Eurotunnel, bad press, possible future competition. Oh dear!

 

[A60K]

Interesting point about hours - in my contract it states that the company may require me to work extra hours according to workload. I'm not in a safety critical role, so that's obviously a key difference.

Is there a provision in contracts or union agreements for maximum shift times for safety critical workers to be overridden in an emergency situation, or is it entirely down to the goodwill of each member of staff on the ground?

OT: I was taking ET's statement to mean that, as well as asking Eurostar to fund another of the tunnel rescue locos, they have also asked Eurostar to provide a dedicated passenger train based at the tunnel entrance for emergency evacuation - rather than using a car shuttle (because people complained about sitting on a dirty floor), or rather than sending an empty Eurostar train from Paris or London, or rather than emptying a nearby Eurostar train at Frethun or Ashford. Is this your understanding, or do they not mean that?

 

[ralphchadkirk]

No safety critical worker can work more than 12 hours at a time, and if they do work 12 hours they cannot work until 12 hours later. Not explained very well I know!