|
As you will probably be all too well aware London Underground suffered two derailment incidents; one on the 17th October 2003 on the Piccadilly Line in the Barons Court area, the other at Camden Town on the 19th October 2003.
The cause of the former appears to be relatively straightforward in that it appears a cracked rail had not been detected and when it finally failed, it caused the derailment of an eastbound Piccadilly Line train.
The second was far more serious, it led to personal injuries and has caused huge disruption to the Northern Line service which continues as I write this.
The following is reproduced form London Underground's web site and is the initial report into the incident.
'Camden Town derailment investigation – initial report
London Underground today published the initial report of the investigation into the derailment of a Northern line train at Camden Town.
A Northbound train, travelling from Morden to High Barnet via Bank, derailed at approximately 20mph as it approached Camden Town station at 1001hrs on Sunday 19 October. Six passengers were taken to hospital.
The key initial findings of the investigation:
The train was being driven correctly and within speed limits for that section of the track; The driver tested negative for drugs and alcohol; The train driver activated a "mayday" call and the emergency services were summoned; The investigation found no single immediately obvious feature that would be expected to lead to a derailment but it is clear that the left wheel on the bogie was subject to downward and outward force beyond that which it was designed to tolerate; Inspection of the points at the derailment site found no obvious defects with replacement parts or the way that they had been fitted; The wheels and bogie of the derailed part of the train were damaged making inspection more difficult but it has been possible to establish that no immediately obvious pre-existing defect was present; The points and signals were operating correctly; The locking mechanism of the points, which had been worked on the night before the derailment, was inspected and the work had been correctly carried out, checked and signed off before trains were allowed to run; There is neither evidence of sabotage nor any evidence to suggest that a foreign object was present on the track; The track supporting structure had not shifted.
London Underground's Director of Safety, Mike Strzelecki said: "We welcome the initial findings of the investigation. We can now concentrate on understanding on how the out of balance forces that caused the wheel to derail could have arisen.
"We will be using the "Vampire" computer model, a tool developed and operated by independent experts, which can represent the dynamic interaction between the train and the track. We expect to have preliminary results within days but fully validated results will take longer to obtain.
"We hope that staff Health and Safety representatives from both LUL and Tube Lines will join us on the investigation team so that we can work together to improve safety on the Tube."
An executive summary of London Underground's "Initial Report of the Investigation into Derailment at Camden Town on 19th October 2003" follows.
Initial report of investigation into derailment at Camden town on 19th October 2003
1.0 SUMMARY
1.1 At approximately 1001hrs on Sunday 19th October 2003 a northbound train derailed on the approach to Platform 3 at Camden Town station. Unfortunately, seven people needed to be taken to hospital as a result; two of the injuries were serious, one a broken femur and the other a head injury.
1.2 The train started service at Edgware station at 0805hrs and travelled to Morden arriving at 0914hrs. At 0920hrs it commenced a journey from Morden via Bank, destined for High Barnet. It departed from Euston at 0958hrs and became derailed on the approach to Camden Town. The train was driven in a manner completely consistent with the recommended driving practice and speed limits for the section. The Train Operator, who had driven the train throughout its trips that day, was tested after the incident for the presence of drugs and alcohol and was passed clear.
1.3 At the point of derailment, the train was travelling within the 20mph speed limit. As the train traversed a set of points taking it from the City Branch towards Platform 3 the front bogie on the last (6th) car became derailed. The front of the last car collided with a wall between two diverging tunnels. The resulting shock caused the rear of the preceding (5th) car to pull to the left, scraping the tunnel wall. The rear bogie of the 5th car derailed and the coupling between the 5th and 6th cars parted. The automatic braking system stopped the train at a point where the front two cars were fully at the platform.
1.4 12 previous trains, all of the same type, had passed over the route concerned on the day of the incident, all without difficulty.
1.5 The Train Operator activated a "mayday" call and the emergency services were summoned. Customers from the front five cars were evacuated via the cars at the platform. The station was evacuated and the situation of the customers in the 6th car was assessed. At 1015hrs London Underground Emergency Response Unit arrived, other emergency services arrived from 1016hrs onwards. By 1110hrs all customers had been evacuated from the train, 7 being taken to hospital. A small number of others had received medical attention at the station, but did not need to attend hospital. Customers from three other trains stopped in tunnels as a result of the incident were also evacuated, this too being complete by 1110hrs.
1.6 As a result of the incident, services on the Northern Line were severely disrupted. By 1030hrs, "shuttle" services were in the process of being introduced on the Edgware, High Barnet and Morden to Charing Cross sections. These were supplemented by special bus services as soon as practicable. At the time of writing the route through the incident area remains out of use and enhanced special bus services are in operation.
1.7 Since the incident, the relevant parts of the track, the train and associated signalling and point locking systems have been closely examined.
1.8 The basic track configuration in the area was introduced 25 years ago; components subject to wear have been replaced as part of routine maintenance over that period. The configuration is constrained by the layout of tunnels and tunnel intersections constructed in the early 1920s. The route consists of a relatively tight curve on a falling gradient followed by a set of points that take trains ahead to Platform 1 or, through a further tight radius curve and a trailing point, into Platform 3. The curve into the area is of bullhead rail and is fitted with a check-rail, the point-work is in flat bottomed rail. As the wheels of a train traverse this section, they experience a complex succession of forces as curve radius, rail type, gradient and the inclination of the rails change.
1.9 Inspection of the track, including the points, found no single immediately obvious feature that would be expected to lead directly to a derailment. Close examination and measurement have allowed the path taken by the first wheel-set which derailed to be traced. It is clear that the derailment occurred because the balance between the downward force and the outward force on the left wheel of the set went outside of the tolerable range. A number of detailed features of the track that require further investigation and analysis have been identified.
1.10 Parts of the points on which the train derailed had been renewed during the night prior to the incident. Inspection after the incident found no obvious defects with the replacement parts or the way they had been manufactured and fitted. A key question raised by this inspection relates to the frictional effects between the newly fitted components and train wheels. A series of measurements of friction values has since been taken at significant locations throughout the point-work, these will be used in subsequent analytical work.
1.11 All relevant parts of the points have now been removed from site. They will be examined further by independent specialists.
1.12 As a precaution, while the cause of the derailment is being investigated, action is being taken to ensure that all other locations, with track having similar features and conditions to those found at the site of the derailment, are identified and managed in a way that will minimise the possibility of any recurrence.
1.13 The relevant wheel-sets and bogie of the train were damaged in the derailment. This has limited the information that can be gleaned by inspection. However, it has been possible to identify that no immediately obvious pre-existing defect is present. The train has been removed from site and subjected to more detailed examination and measurement, the results from which are awaited. These results will be vital to establishing a full understanding of the behaviour of the wheels and bogies during the incident.
1.14 The status of the signalling system and the associated locks that prevent points moving while they are being traversed by a train were checked after the incident. It was found that the points were correctly locked and that the signals were showing the correct aspects. The point locking mechanism forms an intimate part of the points and had been worked on during the night preceding the incident as part of the work to replace point components. Inspection after the incident found all parts to be in place and operating correctly. Examination of records has shown that the work on the locking mechanism was correctly planned, overseen by a properly competent person and "signed off" properly before trains were allowed to run.
1.15 The possibility that the track, train or signalling could have been interfered with by an unauthorised person has been considered. There is no evidence to suggest that interference occurred. The Investigation Team is not pursuing this matter further.
1.16 The possibility that a foreign object may have caused or contributed to the derailment has been considered. There is no evidence to suggest a foreign object was present. The Investigation Team is not pursuing this matter further.
1.17 The possibility that the tunnel or track supporting structure had shifted has been considered. It is evident that it has not.
1.18 It is to be noted that the environment at the derailment site was warm and dry and would almost always be so.
1.19 The work of the investigation is now concentrated on forming a full understanding of how the out of balance of forces on the first wheel to derail could have arisen. The key route to this understanding lies in the use of a computer model, a tool developed and operated by independent experts that can represent the dynamic interaction between the train and the track. Preliminary results from this work are expected by 28 October 2003, but fully validated results will take longer to obtain.
1.20 The Investigation Team has had Staff H&S Representatives nominated to it from Tubelines and from London Underground. An initial briefing was given to the Trains Health and Safety Council members on Monday 20th October and a meeting with the Northern Line Health and Safety Representatives is taking place on 24th October. Full involvement in the investigation of all the nominated representatives will take place from 28th October.'
So, as you will see, there is no conclusion as yet as to what the cause of the incident is but, in my view, the report seems to have ruled out track failure or defects and speed does not appear to be an issue. This tends to point to a train related failure.
No doubt further reports will appear as the investigation continues.
Photos from the incident site can be viewed here.
Added 27th October 2003
Since the original posting above, developments of course continue apace!
The BBC has posted an item on the topic of safety on London Underground, with particular reference to the Camden Town and Barons Court incidents which can be viewed here, and apparently there will also be an update of the 'Kenyon Confronts' item to be aired at 1930hrs on Wednesday 29th October 2003.
In order to maintain a balanced view on the topic the response by London Underground can be reviewed here. This is interesting in as much as it gives detail of the measures that are in place to undertake track inspections, the frequency of these and by whom they are undertaken.
Added 29th October 2003
As has been well covered in the media, the Trade Unions - and the RMT in particular - have been expressing (rightly and understandably) concerns over safety on London Underground, although personally I have some reservations about the proposed course of action as has been outlined by the RMT's General Secretary Bob Crow.
On the 28th October 2003 the Unions met with London Underground, and a press release concerning this can be read here. Again - in the interests of balance - I have tried to see if there has been a response from either ASLEF or the RMT, but I find that, at the time of writing, no response has been posted on either of their websites.
It will be interesting to see the outcome of the investigation promised and also the reaction of the unions, once the investigations have been completed.
Added 3 November 2003
Services were finally restored to all destinations on the Northern Line on the 30th October 2003, but with some limitations imposed whilst the enquiry into the incident continues. London Underground's Press Release on the subject can be read here.
Added 2 December 2003
The reports on both the Camden Town and Hammersmith derailments have now been published, and a summary of the findings and a link to the full reports can be found here.
From the quick read I've had of the two documents so far it seems to me that - as far as the Hammersmith incident is concerned - Metronet are putting their corporate hands up and saying that the track had not been well maintained (although in fairness, this probably predates the transfer to Metronet) and saying that things will improve.
The Camden Town incident is more complex. Despite my comments above, this does, after all, appear to have been a track related incident, caused through a number of factors which, as defined by Sod's Law, conspired to come together to cause the incident. There is also the possibility that routine maintenance to the train involved may also have exacerbated the situation, and this aspect continues to be looked into further.
As I mentioned earlier, the RMT are intending Industrial Action over the issue and members have now been balloted and action is proposed for the week commencing 7 December 2003 - further details can be found on LU's web site. I am not a member of RMT, and my own union remains silent on the matter. I spoke to one of my own Union representatives - the comment received was ' the driver involved was one of our members and we're more concerned about her situation'. Personally I think that speaks volumes.
As for the longer term, the Northern Line continues with the arrangements detailed above. My good friend Tubeprune has offered some comments about this. See his comments here and scroll down to 'Northern Line Disorganisation'.
Update added 3rd February 2004
The final report into the Camden Town Incident was released on the 2nd February 2004 and a summary of this can be read here where it is also possible to download the entire report, should you wish to do so.
Essentially it confirms the findings of the interim report, in that a combination of factors conspired to cause the event. One of the major contributors appears to be the design of the points switchblade and that despite having been an approved design since 1968 there was a minor weakness in the design. This is now being addressed and a redesigned type of blade is in development. This is not the only location on London Underground where this design is used and I am sure it will see a replacement programme introduced once the redesign is completed, though I am sure that Camden Town will be the first site to receive the new design.
However, pending the finalisation of this, Northern Line services continue to be affected as the set of points in question quite correctly remain unavailable. I know the intention was for a revised timetable to be be completed by January 2004, though I am uncertain whether this has come into operation.
|
