Why does it take so long to mend an escalator?

Peter Campbell

Stepping onto an escalator is an act of faith. From time to time you see people poised at the top, advised by instinct not to launch themselves onto the river of treads. Riding the moving stairs is an adventure for the toddling young and a challenge to the tottering old. Natural hesitancy puts a limit on throughput. London Underground escalators carry passengers at a top speed of 145 feet per minute – close to the maximum allowed under the British Standard specification. There is little temptation to run the machines faster, as trials show that above 160 feet per minute so many people pause timidly that fewer are carried. In the early days they had to be persuaded to get on at all. A one-legged man, ‘Bumper’ Harris, was hired to ride for a whole day on the first installation – it was at Earls Court – to show how easy it was. Some people were sceptical (how had he lost his leg?) but others broke their journey there just to ride up and down.

Competence, once achieved, breeds contemptuous agility: young men run down, two steps at a time, and stop aggressively behind anyone who has ignored the notices telling them to stand on the right. London Underground began promoting a walk-or-stand culture in 1944 – ‘Here’s another bright suggestion, standing right avoids congestion.’ Silly boys run up the down-escalator and arrive panting at the top – sometimes having overtaken the line of passengers on the parallel, upward-moving flight. In 1954 a man was fined for sliding down the moving handrail. He said he was in high spirits after getting married.

Most of those who use escalators regularly become calmly capable. They even begin to notice differences between one kind and another: to realise, for example, that those on the Underground are exceptional – longer and wider, generally speaking, than the compact shop and office variety. This is because more is demanded of them. They must run 20 hours a day, 364 days a year; they must cope with heavier loads – bags, trolleys and pushchairs, as well as up to 13,000 people an hour. Even the weight of those who dutifully stand on the right must be taken into account, because it means that the steps are stressed unequally.

The trip Underground escalators take you on is also different from most others. Descending into, or rising from, the depths of the earth is not the same as gliding up and down ramps which cut their way, level by level, from bright to still brighter light. The deep Underground lines are a region of darkness, no matter how many fluorescent tubes show the way. Stand on the edge of a platform and look left or right into the black shadow of a tunnel arch; feel the admonitory wind of an advancing train; hear its distant clatter, see its lights glimmering on the rails. As the carriages rumble loudly towards you, you may find yourself visited with an urge – common to the Tube and high places – which inverts the desire to step back and be safe into an imagined jump forward into the void. You see how the Tube came to supply modern images of hell. Eliot begins the third part of ‘East Coker’: ‘O dark dark dark. They all go into the dark.’ He lists some of them: ‘The captains, merchant bankers, eminent men of letters’. Not the current passenger profile – perhaps he had some other dark place in mind. But a few lines later it is the Underground he turns to for an image of spiritual vacancy:

Or as, when an underground train, in the tube, stops too long between stations
And the conversation rises and slowly fades into silence
And you see behind every face the mental emptiness deepen . . .

Even the wonders of the latest addition to the Tube, the Jubilee Line Extension, have hellish connotations: the darkly sublime spaces below Westminster suggest a stage set for a modern production of Orpheus in the Underworld or Dante’s Inferno. The long escalator which has been installed in the National Portrait Gallery is, by comparison, a stairway to paradise.

Although the underworld of the Underground is as unnatural for us as it is for the black mice you sometimes see making clockwork runs between the train tracks, both mice and men have come to depend on it. The descent to the tunnels through which the deep lines run is a tax on the spirit that is paid willingly because it makes it easier to live in an old, tight-packed city. But when the system fails it is strongly resented. A railway is planned, and therefore in theory controllable. Traffic jams are, by comparison, a natural, disorganised jostling – as old as towns themselves. So although delayed buses are just as irritating as non-running escalators they seem more excusable. In Red for Danger (1955), his classic history of railway accidents and railway safety, L.T.C. Rolt points out that most disasters – ships sinking in storms, volcanic eruptions smothering towns, earthquakes levelling them – reveal man as the victim of forces against which he is powerless. In the case of railway accidents the reverse is nearly always the case: ‘It is in the contrast between trivial error’ – a single mistake on the part of an engine driver, guard or signalman, fitter, shunter or permanent-way man – ‘and terrible consequence that the drama of the railway accident lies.’ Escalator failures, too, are system failures, not acts of God. So our sour voices, unwilling to accept that these things just happen, demand to know why an escalator is not working – and, more particularly, why it has not been working for so long. It adds mystery to irritation (surely they are eager to get things going again) when there is no sign of activity behind the blue-painted barriers which surround a stalled machine. On a Radio London website a commuter complains that he has ‘seen an 11-storey building in the City go from a hole in the ground to nearly complete’ in the time it has taken to repair the escalators at Holborn. Framed notices give dates – months, and sometimes years ahead – for the end of work in progress.

There are 409 escalators on the London Underground. At present about 95 per cent of them are operational at any one time. Statistics come with a whiff of smoke and a flash of mirrors. Numbers are a distraction when the grind of a necessary escalator is silenced. They do, however, tell you that one dead escalator in twenty is more of a nuisance than you would have guessed, and they put what is demanded of public-service escalators into focus. For a store escalator 85 per cent planned availability is acceptable. Those in airports or the Underground are typically installed under contracts specifying 98 per cent availability and usually achieve 99.5 per cent. As machines age, unplanned outages increase, so a proportion – perhaps half – of the out-of-service escalators on the Underground are machines which age, wear and tear have made less reliable than originally specified.

London Transport is used to explaining the difficulty of making repairs in cramped conditions on a complicated, sometimes old system which had, in many cases, to be shoehorned into a tight space in a station designed for lifts. The mysterious inactivity is not really that mysterious. Most escalators can only be worked on during the four or so hours when the station is closed. Then, mechanics are not put in danger by the moving parts of the machine next door, and there are no passengers to get in the way when machinery is brought in through the ticket hall, or to be panicked by the smell of burning when a welding torch is used.

Such explanations lead to more questions. Have escalators always been so fragile? Can broken ones be read as a symptom of a deeper malaise? Are broken-down escalators evidence that we ask for the impossible: that to get the Tube to run smoothly is politically unfeasible because it would involve so many resources being taken away from the other good things we demand – public and private.

To start with the escalator itself. Just how complicated is it? Not very. Like the steam engine, or the motor car in the days before its internal regulation came to depend so much on electronics, it is a comprehensible machine which has changed surprisingly little since its beginnings in the late 19th century, and hardly at all in its essentials since the 1920s. It seemed to me that having grasped the general principles I should be able to get a good idea of the detail just by looking at one.

At Liverpool Street Station I was taken down underneath an escalator that was being repaired. It soon became clear that it was foolish to think I would be able to read it at first glance. The space is cramped, particularly in the descending shaft, where two escalators are divided by a flight of concrete steps so narrow that two people would have trouble squeezing past each other. And even down there on the stairs, close to the step chains and guide channels, some parts are obscured by others which overlap them. I saw a step being replaced – it took two men to handle it. Repairs done inside the machinery are like those done behind the U-bend of a sink: they demand a contortionist’s double-jointedness as well as a plumber’s strong wrist.

The inner workings of an escalator

The first things you see are not the stairs themselves, however. The open space at the top of the escalator – down under the area where commuters gather to step aboard – is dominated by major machinery: the housings of the electric motor (A) and the gear that controls it and connects it to the sprocket wheels and chains. The latter (B) are the main moving parts. A chain drive from the motor (C) turns the top pair of sprocketed wheels. The space between the step chains – they are like two giant bicycle chains – is bridged by the attached stairs (D). The whole assembly is an endless circulating belt. Any single stair is half the time available to carry people, half the time hidden as it makes its way back to begin once again the working part of the cycle. Each stair has two pairs of small wheels mounted on it. An axle joins the upper pair, the step wheels (E), to the chains. They run in a channel – the step wheel track (F). The lower pair – the trailer wheels (G) – are attached only to the step and run in a separate trailer-wheel track (H). A change in the rate at which the tracks curve at either end of the escalator’s run (I) makes the riser of each step drop down, until it finally disappears and is at the same level as the one following it. During the last few feet of run the steps level out to become the flat surface which emerges from, or disappears under, the comb plate. The teeth of the comb plate run in the slots between cleats on the treads of the steps. The step chains, the moving handrails (J) – driven by another set of wheels (K) – and the balustrades are all mounted on a truss (L), which runs from top to bottom of the shaft: the skeleton of the machine, and its rigidity, critically guarantees the alignment of stairs, tracks and chains.

The chinks in an escalator’s armour are the spaces between step and step, step and wall, and comb plate and step. That is where a shoelace, a scarf, a child’s finger or a foot can get caught – which is bad for travellers – and where small hard objects, dragged along and forced between cleats and comb plate, can chew up the aluminium steps, which is punishing for the machine. (A handful of screws can be absurdly destructive and workers on the Underground are obliged – it’s a rule – to double-bag small metal items.) Although gaps are kept as narrow as possible – the British Standard specification allows a maximum gap of 4 mm – enough gets caught there (and enough people fall and stumble, the most common accident) to make escalators significantly more dangerous than lifts.

Things getting caught between the moving parts is a problem inherent in the design of the machine, and one which may never be entirely eliminated. Lines of yellow paint on the outside edges of escalator steps, below-step lighting and brush strips which nudge feet away from the wall-step boundary improve safety, but are essentially psychological defences. A spring-loaded plate which fills the gap has recently been developed in America, where brushes have not yet been generally accepted, perhaps because they look untidy – there is good evidence that brushes work and it’s hard to see any reason other than looks for rejecting them. Work has also been done on reducing friction between step and wall, to make it less likely that anything that slips into the gap will get caught.

Despite the vulnerability of both machine and passengers, escalator numbers are increasing all the time: a table in the Harvard Design School Guide to Shopping shows that in one year alone – 1998 – new installations in some countries were equivalent to more than 20 per cent of the existing total.[*] ‘As more and more architecture is finally unmasked as the mere organisation of flow – shopping centres, airports – it is evident that circulation is what makes or breaks public architecture,’ Rem Koolhaas has written in another context. ‘Two simple, almost primitive, inventions have driven modernisation towards mass occupancy of previously unattainable heights: the elevator and the escalator.’ Of these, the escalator is the winner in places where large crowds have to be taken up or down moderate heights over short distances. The reason for this is clear: a lift leaves people waiting in impatient groups; an escalator lets them stream. In most situations it is the short-distance vertical mass-transport system of choice. Those who design and manage escalators must keep the cost of the machine’s tendency to hurl, pinch and grab at a level acceptable in terms of injury and damaged machinery.

In all kinds of engineering, failure feeds better practice. Rolt’s history describes how accidents have led to safer systems because of action taken after official inquiries – the Railway Inspectorate are his heroes. For the Underground, the King’s Cross fire of 1987, which began under an escalator, was a turning point of this sort. The fire started during the rush hour – at about 7.30 in the evening – and was probably caused by a match that had fallen between the wall and the moving steps. At first it only smouldered – it was later established that other fires of the same kind had probably occurred in the past but had self-extinguished before being noticed. In this case, however, the fire took off. Inflammable gases produced by burning matter filled the space below the escalator; the wooden steps caught fire and the blaze spread to the two adjoining escalators. In the upper ticket hall smoke and toxic gases from the burning ceiling and walls, as well as the flame-thrower effect of the fire in the inclined escalator shaft, contributed to the disaster. Thirty-one people died and more than sixty were injured. Fewer lives were lost than in the Moorgate crash of 1975, but on that occasion there was no foreseeable mechanical or organisational failure, while the King’s Cross fire was perceived, with hindsight, as an accident waiting to happen. It led to a number of changes. Sprinkler systems are now fully automatic – red-painted water pipes are one of the first things you notice when you try to sort out the complicated web of ducting underground. Lubrication in new installations is oil-free – grease in the step guides was one reason the fire grew and spread – and escalators no longer have wooden steps or side panels. And you can’t smoke on the Underground.

The engineering and safety culture of an organisation is formed by such challenges and responses. London’s experience is not unique. A few years ago the Washington Post reported problems, recognisable to Londoners, which were affecting the Washington Metro:

When the Metro was built moving staircases got preference over regular staircases because, engineers figured, they would transport passengers to and from trains more easily and evenly. But as the Metro system has aged and the need for maintenance has increased, escalators have meant headache after headache for the system. Public complaints about idle stairways rise. Metro is under increasing pressure to install more safety devices on its 543 escalators, including electronic sensors that automatically shut down the stairs when an object becomes lodged in them. Hundreds of passenger injuries and five deaths on escalators, including that of a woman who was strangled when her clothing got caught in a staircase, have created a public relations problem for Metro.

In both cities, being more careful has brought its own problems: ‘Every time we put in more safety devices, we are making the escalator more sensitive,’ the Washington Post was told. When the escalator stops unnecessarily the customer sees it as out of service and asks why it is not being properly maintained. Similar complaints follow if fire drills are made more stringent, or if, when hairline cracks appear in steps or drive shafts (as happened in London in 1999), all escalators of that type are put out of service until they have been checked. The public/private argument which dominates debate about the Underground also ran in Washington. The Metro, at the time of the Washington Post’s report, had its own division of escalator mechanics, but some officials wondered whether the decision to keep machinery maintenance in-house, rather than go to outside contractors, had been the right one. Here it was decided to move to supply and maintenance contracts rather than for London Underground to continue to buy and maintain machines itself. The next step, if the Public Private Partnership goes according to plan, will be to contract not for machines but for a given level of service.

Then there are the passengers, who – the world over – do not just walk or stand but stumble, run and sit, not always soberly. ‘It’s not like a department store,’ the Washington Metro safety director was reported as saying (most people stand still on escalators in shops). ‘And remember,’ he added, ‘during holidays we say: “Don’t drink and drive, take the Metro.”’ Take all this into account and you see that engineering an escalator which meets the demands made of it is no small task.

Lightness and simplicity are hallmarks of good engineering. But getting the right balance between manufacturing cost and lifetime performance is equally important. The workload of, say, a domestic power-drill can be almost inconceivably light; its whole lifetime in use is measured in hours. Domestic washing-machines and cars, both lighter and much more reliable than they used to be, are not as solid as industrial versions – laundromat machines and buses – which take heavier punishment. Escalators, too, come in light (department store and office) and heavy-duty (Underground) versions. The former can be bought more or less off the peg; the latter have to be tailored to fit.

In London’s Transport Museum they show an example of Otis lift equipment from 1907. Clumsy-looking, machined from solid metal, it has the bashed-about, old-boxer’s-face look which only machines strong enough to take many decades of punishment wear. The label tells you – it is hard not to read nostalgia in it – that this was ‘heavily engineered and very robust’, and that ‘some units stayed in service for more than eighty years.’ But brute strength is not the only or best route to reliability. Regular surveillance, the routine replacement of parts according to fixed schedules – the kind of maintenance that aircraft receive – is a better one.

Consider three overlapping strategies: build to last, build to budget (but plan to mend) and build to junk. The first strategy assumes the machine will last for ever. Of course, nothing does last for ever, but there are machines that seem made for immortality – Victorian pumping stations, for example, or the steam engines that Kipling’s Calvinist ship’s engineer McAndrew tends: ‘From coupler-flange to spindle-guide I see Thy Hand O God.’ The second is to replace a machine when you calculate that the cost of maintaining it will be more than the cost of borrowing the money to buy a new one. This is what rational motorists, and, I would guess, airlines do. Underground escalators, too, are commissioned on the basis of planned lifetimes and will finish up with many replaced components. The third strategy is to build a cheap machine which requires virtually no maintenance, and lasts long enough for it to seem reasonable to replace it when it breaks down – that is how most household machines are now made.

In Jonathan Franzen’s novel The Corrections, Alfred Lambert, a retired railway engineer, sits in the cellar of his house, struggling with his advancing Parkinsonism and a string of Christmas lights. He is stuck somewhere between the culture of strategy three and that of strategies one and two: ‘At the very end was an unsightly stretch of dead bulbs. He understood what modernity expected of him now. Modernity expected him to drive to a big discount store and replace the damaged string.’ On the other hand,

it offended his sense of proportion and economy to throw away a 90 per cent serviceable string of lights. It offended his sense of himself, because he was an individual from an age of individuals, and a string of lights was, like him, an individual thing. No matter how little the thing had cost, to throw it away was to deny its value and, by extension, the value of individuals generally.

He had seen the railroad that employed him taken over and asset-stripped. His unrepairable lights – like the only-just-not-working computers and video recorders we put out with the rubbish, or like public housing which has had a shorter life than the first children to live in it – are evidence that the manmade world of solid, real, comprehensible things is being replaced by one in which they die rather than break, and are only different from dead pets in that they lie around, uncorrupted, to rebuke us until they are taken off to a landfill site where they become someone else’s problem.

In fact, the Underground escalators last well. Contracts for new machines typically require that they be suitable for a 25-year span, but many achieve forty years and more of working life – which is, after all, as long as many new buildings are planned to last. A specification to meet a given lifespan must include maintenance schedules and estimates of component lifetimes. Calculations not different in principle from those people make when they wonder whether they should buy a new car must be formalised. Dr Lufti Al-Sharif, who works for the Underground, has written in Elevator World about a model for the asset management of public-service escalators. He details the information which must be available about the whole system, as well as on entities within it, and explains why it must be constantly updated so that the performance over time of individual components, individual machines and types of machine can be audited. Given the right information, disbenefits such as the cost to passengers of hours lost can be factored into plans for new machines. They may help to justify more escalators than traffic flow demands, and wider shafts – allowing maintenance to take place during working hours – by showing how the cost of these can be set against savings in overtime and disrupted journeys. The three-to-a-bank escalators in the stations built for the new Jubilee Line Extension, for example, allow for one to be out of service and for all-day working.

Al-Sharif’s account disabuses one of the idea that when escalators aren’t running it is because no one knows what’s happening – or at the very least of the idea that no one is trying to find out. An article on the 1998 modernisation of the London Underground escalators at Victoria in the same magazine tells how the engineering team cut a 24-week refurbishment schedule to 16 weeks – a story which fits with the feeling you get from talking even very briefly to people who work maintaining escalators and making plans for new ones. I would like to believe that they have something in common with Kipling’s steamship and locomotive engineers – half in love with the machines they must regulate and master.

All parties involved in the current arguments about the funding and management of the Underground are clear that they want a modern transport system. The architecture London Underground commissioned for the Jubilee Line Extension – as good as modern design in London comes – seemed to announce their intentions. But the Underground is also part of the heritage industry, one of the things tourists say they like best about the city. Where another organisation would emphasise the current versions of the brand, the Underground leaves scraps of graphics and decoration which date back to the pre-amalgamation companies. This heterogeneity is reflected in the variety of attitudes one finds when reading about the Underground, or when talking to people who use the escalators and to people who work with them. The ignorant but not unreasonably impatient public fails to see why heavy-duty escalators seem to behave less well than the household appliances they use and discard. Realising that an escalator is more like an airliner, but one for which it is impossible to call up a substitute when it is time for a planned overhaul, makes you more sympathetic. And despite their lack of glamour I found myself beginning to like the machines as machines – to see why, even among people involved in cost-and-use calculations, there is a respect for things so solid, even if they are old-fashioned and over-engineered.

Last November Bob Kiley, the Commissioner of Transport for London appointed by Ken Livingstone, and like him an opponent of the Government’s PPP scheme, wrote to the chairman of London Transport. His letter deals mainly with doubts about the performance regime London Underground Limited (LUL) has developed to monitor the contracts, due to be signed very soon, with the private companies which will take over the Infracos – the companies responsible for the day-to-day running of the Tube. They will not be paid for items delivered (escalators, miles of track, signal systems refurbished and so on) but for providing the service and will, therefore, be penalised or rewarded on the basis of the Underground’s performance: how many trains late, how many dirty carriages, how many non-functioning escalators. Some objective measure of performance had to be agreed, and so a mathematical model was constructed in which information about the system (bits of litter, late trains) determines the value of variables in equations which are solved to give an index of performance – resolving any conflicts will be a question of having our mathematicians talk to your mathematicians. Despite Kiley’s derisive description of its complexity, the Underground says the sums are simple, and got some sixth-formers to run through them to prove it. Seen from outside, the difficulty of the calculation is not as concerning as the principle which underlies it. Kiley’s doubts seem reasonable when you think of the problems that another performance-based measure – hospital waiting-lists – has brought. Models and monitored performance are essential management tools. They can give answers to questions like ‘Are we doing as well as our competitors?’ ‘As we did last year?’ ‘As we could?’ Profit, turnover, customer satisfaction and so on can be compared and targets set. When the calculations are used to define outcomes – and when these outcomes cannot be measured simply – the potential for argument and for the distortion of the system to meet the model’s requirements (which is what seems to have happened in the case of hospitals) is considerable.

That is not a case to argue here, however. Nor is it particularly relevant to the question which began all this: why does it take so long to mend an escalator? As far as that goes I am willing to believe what I am told: that escalators are big, complicated machines packed into tight shafts and there aren’t many hours when you can work on them. More money wouldn’t remove those obstacles to seamless service, nor would improved logistics. In fact, a large influx of capital would, in the short term, increase time-outs – it takes longer to replace an escalator than to maintain it – even though the end result would be fewer maintenance sessions. There are other issues – for example, how far competitive tendering leads to more fragile systems. Fear of litigation, as well as stricter safety precautions, are a further reason for delays; no-risk strategies and the strict apportioning of blame are always going to be enemies of smoothness and expedition. Nor should the stalled escalator be taken out of context. If other equipment failures – failures in signalling systems, for example, which seem to be entirely due to long-standing underfunding – were put right, one would scamper down a stalled escalator once in a while quite cheerfully.

[*] Rem Koolhaas et al’s Harvard Design School Guide to Shopping was discussed in the LRB by Hal Foster (29 November 2001).