Earlier this week I was in Shanghai for CDNLive China. More about what was said there next week. Today's post is about getting to the hotel where CDNLive was held from the airport. Most people just take a taxi, but I like to try and use the local transportation systems.

One thing you can experience in Shanghai that you can't in many other places in the world is to take the maglev train from Pudong airport into the city. Maglev, which stands for magnetic-levitation, are trains that don't have wheels. Instead, they use magnets to hold the carriages about 1cm above the track, and use linear motors to move the train. Since there are no wheels, there is only air resistance, no rolling resistance, and no issues with unsprung weight like in fast conventional trains.

Maglev trains really only have one moving part, the train itself. Most of the energy is used to accelerate the train and overcome wind resistance. Apparently, very little energy is involved in lifting the train just above the tracks. The tracks themselves are metal plates on concrete (see the picture I took), but there are no magnets there, so they should be fairly cheap to maintain, although they do have to be very precisely aligned—the train is flying fast just a centimeter or two above the track. I think they are made of aluminum since the electrical characteristics are very important, and you want low electrical resistance to get big eddy currents. Also, unlike high-speed rail, the track doesn't get battered hard and so require regular adjustment. After all, the train doesn't touch the track, it is just above it.

This is the fastest maglev train in the world, with a top speed of 430 km/hour, which is 270 mph. However, most of the time it runs at "only" 300 km/h, which is the speed it went when I went from the airport into town. On my way back to the airport though, I was on one of the fast ones that reached its top speed. See my photo at the start of this post showing the speed. It is really noticeably faster just looking out of the window for the few minutes in the middle of the journey when it is at top speed. The distance is 19 miles and it takes just seven minutes. For comparison, San Francisco airport is about 13 miles from downtown and BART takes 30 minutes (partially, to be fair, because it stops at other places—the Shanghai maglev is non-stop).

Time ranks it as the #1 thing to do in Shanghai. I'm not sure I'd go that far, but as an engineer, it is interesting to experience. The cost is just 50 RMB (about $7) and I think you can get a discount if you landed at the airport, although I have a Shanghai subway card (like Clipper in the Bay Area) so I always just use that and avoid needing to buy a ticket at all. Since maglev is the fastest train technology available, I was actually going on the fastest commercial train in the world. By comparison, the Japanese Shinkansen bullet trains and the French TGV both go at a maximum speed of 320 km/h, the same speed the maglev goes on its slow runs. Of course, all of these have done faster runs under controlled conditions. The Shanghai maglev has been run at over 500 km/h, and the TGV achieved 575 km/h (over 350 mph) in 2007, which is still the world train speed record.

(By the way, #4 on Time's list of things to do in Shanghai is to eat at Din Tai Fung, the Taiwanese noodle and dumpling restaurant. But here's a tip if you live in Silicon Valley: there's one in Valley Fair. There's usually a wait of at least an hour, so put your name on the list and go shopping. The system will text you when you get near the front of the line. According to their website, they are also in San Diego, LA, and Seattle, but I have no personal experience, just the one in San Jose. But highly recommended.)

I tried to find out just how viable the maglev is financially, as part of trying to understand why we don't have more maglev in the world. On the generic page covering all things maglev, Wikipedia describes it as:

The line is currently the first and only commercially successful, operational high-speed Maglev train.

That's technically true since the word "operational" is in there. There were a couple of projects before that (see below).

But then on the page covering just the Shanghai line, it:

The line's balance of payments has been in huge deficit since its opening.

So who knows. It is certainly heavily used. It runs every 15 minutes (20 minutes in the late evening) and when I've been on it has varied from packed to half-full. But unlike other special railway lines I've used from airports, it doesn't whack the businessmen with what the market will bear. Its $7 price is trivial compared to the Heathrow Express to London Paddington at £25 or the Arlanda Express from Stockholm Airport to the main train station at 300K, both of which come out to be about $30. But the maglev is expensive in that it is seven times the cost of the subway which is 7 RMB (about $1). London is the same, the subway is more like £4 per person although it obviously takes a lot longer. But before my kids moved out, I wasn't going to pay £100 to save 30 minutes getting the family into town.

The First Maglevs

Maglev technology was mostly invented by Eric Laithwaite at Imperial College in London. He first invented the magnetic linear induction motor back in the late 1940s. Then, in the 1970s, he came up with the magnetic river, which allows the motor to provide both lift and forward propulsion and be stable. That was what was needed to make maglev workable. Of course, thousands of engineers made the principle into real trains.

The first commercial maglev was in Birmingham, England. It was a slow-speed shuttle between the airport and the nearby train station 600m away. It ran for 11 years from 1984 to 1995. Since it was the first, it was just called MAGLEV. (The British like to do that, and love to point out that, for example, the British Open in golf is actually The Open Championship since there weren't any others when it was named.) A few years ago, someone bought one of the carriages on eBay for £100. Nice place for a cuppa tea.

The second commercial maglev was in Berlin, Germany. It operated from 1989 to 1991. It was just less than a mile. But it became redundant once the wall came down in 1990, and closed soon after.

The third was...Shanghai. It opened on January 1, 2004.

There are several maglev test tracks, even one in the US, and a few systems that have come and gone. However, today there are still just a few maglev systems that are operational, all in Asia:

• Shanghai
• Incheon in Korea, from Incheon (Seoul) Airport to the subway and nearby Yeongjong Island, with an operating speed of 110 km/h (about 70mph)
• Two short lines in Japan
• Beijing S1 subway line, which opened relatively recently in 2017 and has a maximum speed of about 60 mph

The Chūō Shinkansen

Maglev seems to struggle to justify its cost. The line itself is just concrete and aluminum plates but the tolerances are very tight since the train is hovering just a centimeter or two above the track. Building the Shanghai line required them to double the number of supports for the line from what they planned to ensure that the line was as even as required, which obviously blew out its budget.

But the big maglev project in the world is the Chūō Shinkansen. English speakers seem to assume the word "shinkansen" means bullet train, but actually, it just means "new line".

The Chuo Shinkansen is under construction to link Shinagawa (Tokyo) to Nagoya, with plans to extend it to Osaka. Its maximum speed is planned to be over 500 km/h. Tokyo to Osaka should be just over an hour. The JR website says that:

Eighty percent of the 286 kilometers (177 mile) Maglev bullet train track will be located underground, passing under urban sprawl and mountainous terrain.

That is why it is expected to cost ¥9T. But you can't go on it any time soon. Shinagawa to Nagoya is expected to start in 2027, but all the way to Osaka not until 2037. It will use superconducting magnets on the trains, which sounds like very expensive technology given all the refrigeration that will be required. From JR again:

The superconducting coils use Niobium–titanium alloy cooled to a temperature of −269 °C (4.15 K) with liquid helium.

Try It

Anyway, I realize that most readers are probably not getting on a plane to Shanghai anytime soon, so this is of passing interest, but it is wonderful technology and I don't entirely understand why it hasn't been more widely deployed. If you are going to Shanghai, don't be boring and get a taxi. Instead, get the fastest train in the world.

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