Dilemmason doorsDoors are obviously a vital part of the coach - butcan be a troublesome component. Piers Connorexplores the subject of doors

The devil, they say is in the detail andnowhere is this more true than in theissues surrounding train door systems. In

almost every stage of the life of a railwaypassenger coach, doors give trouble, startingwith design, continuing through fitting andsetting up, day-to-day use, safety issues andending with maintenance problems. Onemanufacturer suggests that although doorsmake up only 2-3% of the total car price, theyprovide up to 25% of the operational relevance.

DesignAt the design stage, thinking starts with howmany doors there should be, how big shouldthey be, where should they go and who shouldcontrol them. For the modern railway inBritain, we seem to be stuck with two designs,the long distance end door arrangement or the

commuter 1/3 + 2/3 doorway positions.Powered doors cost seats, so they are kept to anacceptable minimum. A Class 423 TrailerSecond vehicle with 10 slam doors on eachside had seats for 98 passengers. Theequivalent vehicle of Class 450 that replaced ithas 56 fixed and nine tip-up seats, a third less,and it has four doors per side, three fifths less.On the plus side, we have a safer car bodystructure.

Door opening width is crucial. A doorwaymay be wide enough to allow two persons topass at the same time (1,400mm) but this willbe prevented if anyone is standing against thedraught screen – the proverbial ‘door sentry’.To mitigate against this, a 200mm standbackspace or a wider doorway is essential. Since theearly 1990s the London Underground hasadopted a 1,600mm double doorway as

The last day of slam-door service atWaterloo on 25 May 2005. Note yellow

door edges, permitting conductor to see ifa door is not properly shut. The unit is Class

421/8 4-CIG ‘Greyhound’ No 1398. Brian Morrison

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1986 stock, where the all-aluminium structurerequired the use of outside hung doors in order toaccommodate the door pillars. During the trials, atrain discarded one of its doors in the tunnel butthat’s what trials are for and, after some years ofbedding in the maintenance process, theproduction versions became very reliable.

Previous construction had doors sliding intopockets in the bodyshell. This was adequate andmechanically simple and it served its purpose foralmost 100 years but it did reduce the interiorwidth of the vehicle and added weight,particularly to the small tube cars. In recenttimes, there has been a drift back to the pocketstyle door for some trains, as seen on theBombardier Classes 376/378 and Hitachi Class395 designs.

Air or electric?Modern door operators are usually electricallypowered and mounted at cant rail level over thedoor void. Floor mounted operators used to bethe rule but difficulties with water and rubbish

entry and the desire to get an obstruction freeguidance system led to the top mounted design.Indeed, so great were the benefits, that therefurbishment of the Class 303 stock for theGlasgow suburban area in 1984 saw the floor-mounted operators exchanged for top-mountedunits at not inconsiderable expense.

Hitachi designers have stuck to air operationfor the Class 395 and they have provided asystem to clamp and pneumatically seal thedoors to allow 225km/h running in comfort.They have stuck to what they know and retainedthe system used for many years on the JapaneseShinkansen high speed trains.

Regardless of what the Japanese do, the UKpreference is for electric over compressed airpower. Air is quick and was better than theavailable electric operators for many years but itcan suffer from the effects of condensation, itneeds extensive pipework and big compressors;the door operators need a reservoir on every carand, in my experience, some muck will get intothe system despite the best efforts of driers,drainers and maintainers.

In 1994, the first UK fleet installation ofelectric operators on the Class 323 units provedthat development had progressed sufficiently toallow air operators to be dropped. LondonUnderground held onto them for many moreyears, largely because they have to have rotary,floor-mounted operators on tube cars since thereis no room at cant rail level for them. For theirnew trains (2009 tube stock and ‘S’ stock), theygot electric operators, despite an assertion to meat the time of the specification by a seniorengineer that it would happen ‘over my deadbody’. Happily, he survived conversion toelectricity.

SafetyOne of the biggest issues for door systems issafety. This is not to say that doors are not safe.Train doors are safer than they have ever been.With the old ‘slam’ doors as originally designed,the problem was that people were assumed toknow how to behave with them. Before lockingwas introduced, many passengers would openthe doors before the train stopped with all itsinherent risks and then jump off at what theythought was a suitable speed. At the majorLondon termini, some seasoned commuters wereable to reach the end of the platform before thedriver. There were incidents of doors beingopened maliciously on trains at speed, or doorsbeing opened by late-arriving commuters astrains departed. There were also a surprisingnumber of occasions where doors opened onmoving trains due to defective catches or locks.We should not forget how dangerous this proved.A Health & Safety Executive report of 1993recorded that almost 20 people were killed eachyear due to falls from moving trains. Eventually,it led to a call for all doors to be locked. Centraldoor locking, as it became known, wasmandatory from 1 January 2006.

With central locking on Mk 3 coaches andpower doors on most other types, trains do notstart until doors are shut and locked andpassengers can’t open them while the train is

moving. Even staff doors have to be locked. Asalways, better safety comes at a higher price.Now, the train starting process is, in someinstances, longer than the time spent gettingpassengers on and off the train. A survey of onetrain operator showed that the time spentbetween the conductor getting ‘Right Away’and the train starting to move could be as longas 23 seconds. This must be frustrating for thelatecomer who stands on the platform for 20seconds banging on the doors thinking theyshould be allowed to board a train that hasn’tleft yet.

DOO or 2PO?The traditional method of train operation had adriver to do the driving and a guard to look afterthe passengers and do ‘station duties’ – checkboarding and alighting was complete, check thestarting signal was off, check train doors wereclosed and, finally, give the driver the bellsignal. Nowadays there is a wide variety of trainstaffing options, ranging from DOO (driver-only operation) to various two-person (2PO)plus modes, using conductors, train managers,customer hosts and ticket inspectors (sorry,revenue control staff) in almost as manycombinations as there are train operatingcompanies (TOCs).

Train door control systems are nowdeveloped according to individual companies’requirements or the latest fashion, depending onhow you look at it. DOO conversion is alwaysdesigned in. Many modern fleets are equippedwith driver-operated door release, even ontrains with guards who are responsible forclosing the doors and providing the startingsignal, so DOO conversion is a simple switch,on the train at least. Another useful DOO aid isin-cab CCTV using on-train cameras. Thesefirst appeared on main line routes in 2005 butLondon Underground introduced a track to trainCCTV system on the Central Line with the1992 tube stock. The tight structure gaugedoesn’t have room to allow car-mountedcameras.

Of course, DOO might seem the obviousmethod of choice for a TOC. It keeps thestaffing costs down, although perhaps not asmuch as we might think, and it reduces thecancellation risks if only one person has to signon to work the train instead of two. However,DOO has proved unpopular with passengerswho, rightly or wrongly, think they are less safewith only one member of staff on a train.

One consideration that may not be widelyappreciated is that guards provides a usefultraining ground for future drivers. It’s all verywell dipping into a pool of on-board caterers,customer hosts or platform staff for drivertraining but, in my experience, few of themknow anything about trains, nor how theyoperate. A guard, on the other hand, gets to bewith the train for most of its work, gets tointeract with the train equipment and the driveron a regular basis and could, given the righttraining and incentives, assist with problems. Inthe current economic climate, driverrecruitment should not be a problem but a

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standard to combat the problem. A wide doorwayprovides a faster loading rate – oneperson/second/door is a typical rate but, ofcourse, it comes at the price of seat loss.

Then there’s the question of how to fit doors -in, on or outside the car body; should they slide,swing, fold or plug or a combination of somesort? What power system should they have andwhere should the ‘door engine’ go – on the flooror in the roof?

For almost 20 years, sliding plug doors havebeen the preferred option. They provide aweather proof, non-rattle, draught free seal butthey need a complex drive system and carefulmaintenance. They are also very slow to openand close, taking up to triple the time for a simplesliding door. They do provide the smoothexterior body line beloved of train architects andthey make exterior cleaning easier.

In London, the trains built for theUnderground since the early 1990s have thedoors mounted outside the bodyshell. This wasintroduced following a trial on the experimental

New Victoria Line stock, showing doors slidingon the outside of the body. Kim Rennie

Sliding plug doors on a refurbished Class 465/1 Networker. Brian Morrison

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alarm operation. You really need to be an expertto see your way out of trouble if a brake supplycircuit breaker trips open in a station platformjust as the train is about to depart.

The TMS bites backThe risks invoked by the use of multiple faultwarnings were dramatically highlighted on anew train on the Underground’s Victoria Line afew weeks ago. Modern rolling stock isequipped with on-board, processor-based, trainmanagement systems (TMS). These offer thedriver real-time information on the state of thetrain and provide downloadable maintenancedata. They can also provide much neededassistance or guidance for the crew if somethinggoes wrong with the train whilst it’s in service.

In one, well publicised instance during a rushhour morning a few weeks ago, a new 2009stock train on the Victoria Line came to anabrupt halt between stations. The TMS scrolleda list of faults triggered by the train. When thedriver checked his screen, a ‘door obstacledetected’ message was top of the list and heinformed the control centre that he had a doorproblem and that the train had stopped as aresult. The emergency brakes were locked on.The control centre and driver started working

together to try to get the door problem sortedout. After an hour without success, it wasarranged that passengers should be taken off andwalked to the next station. The power to thecurrent rails had to be switched off to do it.Another hour went by before everyone wassafely off the train and current was switchedback on to try again to get the train brakesreleased.

Now, one of the things you need to get trainbrakes released is a compressed air supply. Withpower restored, the driver, by now in thecompany of sundry big hats, suits andtechnicians, waited for the train’s air supply torecharge. Repeated glances at the air gauge onhis control desk showed it wasn’t happening. Atechnician was dispatched down the train toinvestigate and he discovered that, on the sixthcar, there was a big hole somewhere underneaththrough which air was noisily escaping. With aquick isolation of the offending bit of pipe, airwas rapidly restored, the brakes released and thetrain driven back to the depot.

And the door fault? There wasn’t one. At theprevious station, a closing door hadmomentarily met an obstruction, probablysomeone jumping on at the last moment. Thetrain started before the ‘door obstacle detected’message had registered on the TMS which,being programmed to hold minor messages untilthe train reached the next station so as not todistract the driver whilst on the move, stored it.Unfortunately, the next stop was not the nextstation, it was the emergency brake applicationinduced by the air loss. The TMS, displayingvarious faults triggered as a result of the loss,correctly showed the loss first but it was scrolledpast by all the other faults so the door obstaclemessage came top of the list. Our poor driver,understandably forgetting the golden rule ofalways checking power supply and air pressurefirst when you have an unexpected stop was,together with a mélange of managers andtechnicians, led up a very long and tortuousgarden path, by a very clever computer.

Lessons to be learned? Most certainly. First,computers (especially those on trains it seems)are not as fast at picking up messages as youmight think, as our door message must havetaken a second or two to get to the TMS.Second, make sure your TMS displays to youwhat you need to know in the right order andthird, don’t forget that when you are up to yourbackside in the proverbial alligators, it’s a goodidea to check that you’re trying to drain the rightswamp.

Piers Connor is an independent railway systemsconsultant and lecturer on railway operationsand engineering.

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TOC’s succession plan should look forward to atime when more drivers need to be taken on.

Training a driver with no previous experienceis a time-consuming business. It can take from15 months to two years to get an off-the-streetrecruit on the front as a qualified and route-signed driver. This period could be cutsignificantly if the applicant has the sort ofexperience of real, on the road, operations that aguard gets with a few years on the trains. Youcould think of it like this: ‘New driver training –expensive; three years’ experience as a guard –priceless!’.

AlarmsA controversial part of the power door operatingprocess is the warning alarm system. This triesto be all things to all men (and women) but areport published by the DfT showed that thesystem is an excellent example of how to irritatethe majority of passengers, disturb residentsliving close to stations, provide a system that isoften misused, cause delays to trains and still failadequately to help the less able.

It describes how the door close warning bleepsare usually interpreted by passengers on theplatform as a ‘time to get on the train’ messagerather than the intended ‘stand clear’ message.

The standard time for the bleep duration was setat three seconds before closure starts, but this hasbeen the subject of a number of derogations dueto the cumulative delays to frequently stoppingservices like the London Underground. And, theopen warning doesn’t help the visually impairedfind the open button nor indicate which side thedoors will open. In an attempt to get over this, onthe Underground’s new trains, a voice tells youwhich side the doors will open. I wonder howmany passengers could tell you which side of atrain is the left or right.

RecyclingMany modern train door systems incorporatesome form of recycling (reopening and closingagain on encountering an obstruction). Despitedoomsayers forecasting train delays caused bypassengers deliberately pushing on doors toprevent them closing, it doesn’t seem to havebecome a serious problem.

London Underground has resisted recyclingup to now – being that much more vulnerable toshort delays of this type – but the company hasaccepted it on its new trains.

LU has also adopted dragging detection. Thisoperates only after the doors are closed andlocked and uses a sensitive door edge to detect a

deformation caused by a trapped strap orclothing pulling against it. Detection will applytrain brakes.

ReliabilityIn failure terms, there are wide variations.Traditionally, power door system failures werereported to be around 50% of all train defectsbut this was in the days when systems on trainswere simpler and door equipment was at themore complex end of the scale. For the oldertrains in service today, one senior engineer toldme that the figure is now more like 25% andsome modern types get as good as 5%. Thebiggest problem, from a maintenance point ofview, is the time and accuracy required to set uppowered doors to ensure trouble-free operationand closure detection within the specifiedlimits.

A useful feature on trains is the externalbodyside light which indicates an open doorcircuit or unlocked door. London Undergroundimported the idea from the US and adopted it inthe late 1940s. It is now standard on all trains.Although it helps to locate a faulty doorquickly, in recent builds it has been hijackedadditionally to indicate such things as brakefaults, circuit breakers opening or passenger

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Open and closed doors on FGW HST at Paddington. The HSTs are fitted with central door locking operated bythe guard, but there is no interlocking with the traction power - meaning it is theoretically possible for a trainto set off without all doors properly shut. Brian Morrison

Experimental power-operated door on Mk 3 coachbeing tried out by Chiltern Railways (p90, lastmonth). Door release on these doors would be bythe driver (allowing release as soon as the train isat a stand), and there would be interlocking withthe traction power. Richard Tuplin

Hitachi-built Class 395, featuring air-operatedsliding pocket doors. Brian Morrison