Managers of overdue and over-budget project say tests still required to get everything right

A year has passed already since the Elizabeth line was due to be opened by the Queen. Cutting the ribbon on Crossrail, renamed in her honour, will not happen in 2020 either: another 15-24 months at least will pass before passengers can board its trains traversing London.

Yet below the capital’s streets, the new railway looks all but ready. Individual stations are virtually done. Just off Oxford Street, the display screens of Tottenham Court Road’s new western ticket hall count down the departures of a parallel universe: trains every three minutes eastbound to Abbey Wood or Shenfield, and to Reading or Heathrow in the west. In place are the barriers, escalators, steel lights, even the big screens for artwork and advertising. All that is missing are the passengers and the trains.

At the bottom of the escalators – just shorter than London’s most vertiginous at Angel tube – the completed platforms are vast and silent, ready for use by 170,000 passengers daily. “This is my favourite view on Crossrail,” says Lih-Ling Highe, the site manager for Tottenham Court Road, looking eastbound along the only curved platform on the railway.

Facebook Twitter Pinterest The Crossrail station at Whitechapel. Photograph: Graeme Robertson/The Guardian

As the far end of the 235-metre platform gracefully arcs out of sight in the distance, only a few workers in orange hi-vis protective gear are dotted around, a further walk from another soul than usually possible in the heart of London. The floor-to-ceiling safety screens separating waiting passengers and trains are still pristine; the walls and platform spotless, despite the tunnel having recently been smoked out to test the emergency extractor fans. Beyond, even the gold-leaf artwork on the eastern ticket hall ceiling has been painted.

But, as the Crossrail chief executive, Mark Wild, admitted to a London assembly hearing last week: “If you go to Tottenham Court Road and Farringdon they are impressive developments; you think they look ready to go.

“But behind the mask there is a lot of integration work to do ... It’s complex work and we can’t take any shortcuts.”

Rewriting the software that links the various signalling systems is an overarching unknown. Wild is waiting for more clarity before announcing a fresh target opening date in January. If the latest iteration is good enough, Wild said trial running of trains – normally a nine-to-12-month process – could proceed quickly enough for the Elizabeth line to open under central London in spring 2021.

Even at Whitechapel, one of two stations significantly behind schedule and over budget (by a staggering 500% to £659m) the subterranean Crossrail elements verge on completion: crucially, with an emergency exit for train crew. That will allow test trains to stop and enable Whitechapel – unlike the further delayed Bond Street – to open with the rest of Crossrail.

Above ground, work continues on a new station concourse that passes over the two other railways to reach the escalators to the Elizabeth line. Whitechapel was a notorious interchange even before Crossrail: the only place where the overground is below the underground. Hemmed in by schools, pubs, flats and businesses, Crossrail had to build a new Whitechapel entrance and ticket hall for the duration, along with another shed to house a concrete mixing plant and two gantry cranes, to minimise disturbance.

Facebook Twitter Pinterest Crossrail workers on site at the Whitechapel station in East London. Photograph: Graeme Robertson/The Guardian

Jim Forrest, the site manager, says it will all be ready before Crossrail is done: underneath board and foam cladding are the tiles and handrails that give the look of a finished station. What is visible is a fraction of the work done, he says: “What you don’t see is the thousands of miles of communications cables and wirings installed.”

Complex systems link each lightbulb and element to a control centre in Romford and are engineered to safety levels most passengers would be unaware of. Every glass-reinforced concrete panel lining the tunnels has dimples for acoustics and is doubly attached with hidden steel lanyards: “So they don’t fly off if there’s a blast. It’s all there.”

Delays are not only frustrating for the commuters crammed into the Central line and other transport services still taking the strain: it threatens to unravel London’s finances. Plans such as a walking and cycling bridge, the rebuilding of Camden station, and the Piccadilly line signalling upgrades have been paused.

Facebook Twitter Pinterest The new Tottenham Court Road Crossrail station. Photograph: Graeme Robertson/The Guardian

Tony Travers, the director of LSE London, says: “Every day it takes longer, it costs more money – and every day it denies TfL the fare income. So they’re losing twice.”

In TfL’s business plan, updated last week, “you can start to see the true horror of the losses”, Travers says – some £1.35bn over four years. As well as upgrades, cherished policies will disappear, he predicts. “It’s almost inconceivable that Sadiq Khan [the mayor of London] will extend the fares freeze ... TfL needs every farthing it can get.”

At Whitechapel, we stumble on a member of the assurance team angrily grappling with an imperfect door

Despite the pressure, and whatever the delays and cost overruns, Wild and the managers’ focus is clearly on getting it completely right before delivery.

At the station level, much of the work remaining underground is “snagging”. At Whitechapel, we stumble on a member of the assurance team angrily grappling with an imperfect door, whose handles and locks are in the wrong place.

At Tottenham Court Road, cladding has been removed to readjust the bolts on a screen: tight enough to hold all in place but not at the optimal specification for the part. “It’s that level of assurance and attention to detail to make sure everything is absolutely right,” Highe says.

Crossrail has fallen from grace after the boastful overconfidence of previous executives – but optimism remains. Highe shows a secret bit of extra tunnel between the platforms of Tottenham Court Road, needed in construction but redundant for now. Rather than fill it in, they kept it behind closed doors: it may well, she says, prove useful in the construction of Crossrail 2.