Are superfast trains speeding down the tracks?

At the time the UK was completing its first stretch of high-speed rail in 2007, China had barely left the station. Nearly a decade on, Britain still has only that same 68-mile (109km) stretch of track, but China has built itself the longest high-speed network in the world.

At more than 12,000km (7,450 miles) in total, it is well over double the length of the European and Japanese networks combined.

So if you want to get a sense of what the future of rail travel might look like, China would seem to be the place to come.

Vacuum velocity

As it stands, train technology doesn’t seem to have changed much for decades.

The UK may have just received its first Hitachi-made Super Express high-speed train capable of running at up to 140mph (225km/h), but this is hardly a quantum leap forward.

The much-loved InterCity 125 – as its name suggests – could do 125mph back in the 1970s. And France’s TGV and Spain’s AVE travel at more than 190mph.

So when will we see truly superfast trains bulleting through the countryside, capable of speeds of several hundred miles per hour?

A lot of hopes are being pinned on “evacuated tube transport” (ETT) technology, inside China and elsewhere.

Friction is the enemy of speed, and air friction increases exponentially the faster we go. This means the current upper limit for conventional high-speed trains is about 250mph.

So the theory is that by running trains through vacuum tubes, and raising them off the tracks using existing maglev [magnetic levitation] technology, drag could be reduced to near zero.

These ETT trains could potentially travel at over 1,000mph.

While the much talked-about Hyperloop proposed by Tesla Motors and SpaceX founder Elon Musk, will be trialled in California next year, China is already ahead of the game.

Dr Deng Zigang, from the Applied Superconductivity Laboratory at China’s Southwest Jiaotong University, has built just such a system: a 6m radius vacuum train tunnel and he has begun testing.

Hot air?

But these are early days. Reports suggest Dr Deng’s small train has so far only reached speeds of 25km/h, and there are many who doubt whether such technology will ever become a reality.

“Viable public transport needs a lot more than experiments,” says Prof Sun Zhang, a railway expert from Shanghai’s Tongji University.

“It needs to be achievable in construction, they have to be able to control the risk, and they have to have concern about the cost.

“So my personal view,” he adds, “is that, at this stage at least, this is just a theory.”

Jeremy Acklam, transport expert at the Institution of Engineering and Technology, agrees that a combination of maglev and vacuum technologies would be “very much more expensive” than traditional high-speed rail. “We need to ask ourselves how much extra speed is worth?” he says.

Maglev tech is expensive because the repelling magnets and copper coils use a lot of electricity, and the track infrastructure is far more complex than conventional steel rails.

“Achieving a vacuum across a long distance is a significant engineering challenge,” says Mr Acklam.

Then there are the safety issues.

How would passengers be evacuated if the train broke down, and how would the emergency services gain access?

There’s also the obvious point that many people might not like travelling in a tube with no windows to look through.

Courtesy: BBC
Read more » http://www.bbc.com/news/business-31608679?ocid=socialflow_facebook

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