How can kodama/hikari/nozomi Shinkansen trains run on the same track without crashing into each other?

Question

Potential answerers will know the following info, but I'm including it so that curious readers will know what we're talking about...

Basically, there are three services on the Tokaido Shinkansen (the main high-speed line in Japan): Kodama, Hikari and Nozomi. Kodama stops at all stations en route, Hikari stops at important stations, and Nozomi only serves the largest cities.

All three services run on the same line, but Nozomi can complete the Tokyo-Nagoya journey in 1.5 hours whereas Kodama takes almost 3 hours.

So my question is... how can they run on the same track without crashing into each other?

There are similar track-sharing patterns in Europe, but the headway between trains is longer. For example, there are 2 trains per hour between London and Manchester, but up to 13 per hour between Tokyo and Nagoya!!

And thanks in advance for your answers =)

Yes, they always run on time... but how is it even possible to schedule trains of different speeds at 5 minute intervals? The Nozomi can't just fly over the Kodama waiting at the station right in front of it! =p

To Kodakdude: I have read that article 100+ times. Okay, maybe I'm exaggerating, but I've probably memorised every Shinkansen-related detail on Wikipedia already.

To Terryc: Thanks!! That makes sense.

Hmm... which leads me to wonder: Just how much maths was involved in coming up with the Shinkansen timetable? Seems like a job for the mathematicians!

Answer 1

As mentioned above, there are additional tracks, not just two (one going in each direction), so if say a Kodama train is parked at a station, a Hikari train can "pass" the Kodama train by going on an adjacent track, there for it "overtakes" the Kodama.

For example, there might be 4 tracks at one station, 2 tracks each serving a platform going in each direct, then 2 tracks in the middle that allow trains to pass by the trains stopped at the platform.

If you watch this video:
http://www.youtube.com/watch?v=OCGiS-ae3oc

You can see 4 tracks, (a shinkansen is parked at one of them at the platform) a Shinkansen parked at a station, and another shinkanen behind it "overtake" the parked shinkansen on a seperate track.

When two trains are sharing the same track, then signals and communications keep one train from behind from going into the others behind.

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Maybe?? Your explaination is simple but does not make much sense in actual execution. Because lets say the slowest Kodama leaves last in the hour, the next hour a Nozomi Shinkansen has to leave, so it is behind the Kodama, but the Nozomi's schedule has it arriving at the final station before the Kodama that left BEFORE it. The answer is good signaling and trains overtaking other trains on separate tracks and when the other train is parked at a station picking up passengers.

Answer 2

It's double tracked and one track is inbound and the other is outbound. As another answer says a Kodama can pull into a station while a Hikari or Nozomi shoots through. As it's electric there is an inherent safety factor in that there is only enough current supplied to each track segment to drive one train. As you say, this requires a lot of planning but nothing that would have been beyond the capability of old-fashioned analog computers(rods through punch cards?). I was once onboard a Shinkansen that had to make an emergency stop inside a tunnel due to a power failure. The emergency lights came on and the conductor came on the PA and explained that the smoke inside was just from braking inside a tunnel-good thing I can understand Japanese! We were underway again in about ten minutes. There is actually a coupling behind the nosecone so that a disabled Shinkansen could be shunted to a terminal.

Answer 3

They can run on the same track without running into each other because each Shinkansen has its own departure time. for example: If Hikari leaves first, Kodama would be the second and Hikari Railstar the third Shinkansen.
In your example the Nozomi would leave first since it is the fastest, and would travel again in rotation after the other trains have cleared the track.

Answer 4

On the line i work we have CTC(centralized traffic control)which is a dispatcher hundreds of miles away controlling the movement of trains by computer.He controls the switches and the signal colors at the control points.Then the trains move under signal indication.Think of the signals like city blocks with a signal at each end.If a train is stopped ahead of another, as the train coming up behind the stopped train gets close he will get a flashing yellow(slow to 40mph),then a yellow(slow to 30 mph),then a red(either stop or proceed at restricted speed).When the train ahead moves and clears the block the train behind will get a yellow signal and can move up to where the first train was sitting.The signal colors tell us what speed we can move at and the dispatcher controls when we can move.It's the actual signal system that allows the safe spacing of trains.There's not much math involved in it though besides the signal colors that govern our speeds and the binary code mathematics and the logic circuits that run the computers.

Answer 5

1) Signals will keep the trains separated.

2) when a train pulls into a station, if probably pulls off the main track to a side track, thus allowing other trains to over take or even pass.

3) If the fastest train leaves first and the slowest last, then there is no problems with the above.

Answer 6

http://en.wikipedia.org/wiki/Shinkansen

Answer 7

by always running on time