Close one eye, and it could almost -- almost -- pass for a regular underground train. Close the other, and it looks like a space shuttle from Star Trek.
The truth is somewhere in between. This is the long-awaited new Tube train for London, which features driverless technology, a single "walk-through" interior rather than individual carriages, and advanced air-cooling systems hidden behind the walls.
But it's not all change: the design includes the traditional London Underground colors and typography, as well as seats and interiors that are comfortably familiar.
"London's Tube is one of the most iconic trains in the world," says Paul Priestman, Director ofPriestmangoode, the agency that designed the train.
"We are proud to have designed something that it is part of the very fabric of London life, celebrating all that's great about London's environment: cutting edge technology, rich history and diversity."
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The end of the line for old-fashioned carriages
The fleet of 250 new trains will be "rolled out" in the mid-2020s, and are anticipated to remain in service for 40 years.
A new design was necessary to cope with the increasing demand. Transport for London (TfL) expects London's population to rise from its current level, about 8.4 million, to approximately 10 million by 2030.
The new "walk-through" design will provide up to 60% greater capacity in comparison to the existing trains, allowing lines like the Bakerloo and Central to carry between 8,000 and 12,000 passengers every hour.
"The principal challenge was that the deep tube tunnels are very narrow, so the train themselves are confined to really small spaces," says Priestman.
"We also had to address making the components lightweight and creating enough space for air cooling systems."
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Driving an icon into the next century
The length of the intended lifespan of the trains also presented some challenges. "We needed to think about materials that will 'wear in', or look better with age, rather than wear out," Priestman says.
"What's interesting with transport is that if you design something that looks too futuristic, the likelihood is that it will very quickly look dated. So you need to strike a balance with the design, create something iconic to take passengers into the future whilst avoiding clichés."
As there is currently a range of trains from different periods running on the Underground, Priestman and his team were able to cherry-pick the most important and recognizable elements of past designs, and innovate around them.
"If you look at the London Underground compared to other subway systems, the trains are more comfortable," he says. "We would have liked to have created more floor space but it became apparent early on in the process that this space was required for elements such as air cooling."
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The coolest of Tube trains?
As anybody who has traveled on the tube in the summer will testify, the addition of air cooling systems was of paramount importance. At the moment, only the Metropolitan and District line trains have air conditioning; the new design will enable cool air to be extended to the deeper lines.
Much effort was applied to employing the most lightweight materials available, enabling the new cooling systems to fit neatly behind the walls.
"The new Tube for London will take the city into the future by enriching the everyday journey of its passengers," says Priestman. "It was a privilege to design something so iconic and long-lasting."