The Diamond

[bill937ca]

Anyone know what a Japanese railway means when it says the diamond is changing?

Hint: it's not track.

I will post the answer later.

[Bernard]

My guess (and I do mean guess) is it would have to do with the gate at a RR crossing going down.

[bill937ca]

Good guess, but that's not it.  It's on paper or more recently a computer.

[stevenh]

We totally need more clues :)

I just google'd quickly and came up with things like the "Mitsubishi" 3-Diamond signal which indicates a slower speed restriction in the next block... and also the fact that a pantograph is lowering/raising?

But they don't sound right... my initial idea was that the Boss was getting fired  ;D

Anyway... feel free to lead us in the right direction.

[Shashinka]

We totally need more clues :)

I just google'd quickly and came up with things like the "Mitsubishi" 3-Diamond signal which indicates a slower speed restriction in the next block... and also the fact that a pantograph is lowering/raising?

But they don't sound right... my initial idea was that the Boss was getting fired  ;D

Anyway... feel free to lead us in the right direction.

Don't they have the LED diamonds at the end of the station platform that tells the motorman where to stop his train along the platform (or better yet to say as to how much space the train has left on the platform as where to stop so that all doors can open on to the platoform) . Especially on Shinkansens since the doors need to be aligned up correctly with the openings of the platform handrails.

http://upload.wikimedia.org/wikipedia/commons/thumb/3/3c/500_series_Shinkansen_train_at_Tokyo_Station.jpg/800px-500_series_Shinkansen_train_at_Tokyo_Station.jpg

http://gardkarlsen.com/japan/shinkansen_JR500.jpg

[bill937ca]

Several good trys.  But I think it's time to give you the answer.

When schedule changes occur you will see a reference like "diamond revision"  if you translate the notice. These are notices (in Japanese) for a Nishi-Nippon Railroad diamond revision in March 2008.

http://www.hobidas.com/news/article/81009.html

http://www.nishitetsu.co.jp/release/2007/07_129.htm

Japanese railways have a schedule and a diagram of where all trains will be at any given time. There are multiple diagonal lines criss-crossing on a graph. One axis is the time, the other the stations. That diagram is referred to as "the diamond." With regular interval headways the meeting points form diamonds on the diagram.  Usually we don't get to see the diamond, but sometimes we do.

When the Kotoden retired its fleet of vintage EMUs in 2007, it published a schedule and diamond for the various commorative runs in a pdf (below).  The excursions occurred on August 11 and 12, 2007.   Although the diamond is in Kanji, the station distances match up the Kotohira line station spacings.


http://www.kotoden.co.jp/publichtm/kotoden/new/2007/2007_0811/image/2007_081112_315.pdf

The regular trains are shown with the black lines.  About half of the trains turnback at Okamoto Station.  The red and blue lines are the excursion trains that Kotoden ran.  This line is single track with passing sidings only at stations.

JR has an automated system to make these matrix diagrams, but reportedly it is training its employees on writing these diagrams by hand.  This might be necessary in the event of a typhoon or an earthquake to get the trains back running.

There is at least one model railroad club that uses diamonds in its operations.  There is a track plan which is needed to create the timetable and then at the bottom of the page is the diamond.

http://www.familybook.net/omrc/021208dia.html

There was a magazine that published these diagrams in Japan, but they the text was so small they were almost impossible to read.

So that is the answer!

[bill937ca]

Here's another example

Kotoden retired car 65 on Sunday November 4, 2007

Notice:  http://www.kotoden.co.jp/publichtm/kotoden/new/2007/2007_1104/index.htm

Timetable    http://www.kotoden.co.jp/publichtm/kotoden/new/2007/2007_1104/image/65jikokuhyou.pdf

Diamond: http://www.kotoden.co.jp/publichtm/kotoden/new/2007/2007_1104/image/65dia.pdf

Car 65's commemorative run was on the Kotohira line also.



The last 27 series cars were retired on July 7, 2007 on the Shido line.
 
http://www.kotoden.co.jp/publichtm/kotoden/new/2007/2007_0707/index.htm

Here's the timetable and diamond.

http://www.kotoden.co.jp/publichtm/kotoden/new/2007/2007_0707/image/2007.07.07dia.pdf

[bill937ca]

This another example.

http://pacrimhq.fujitawork.com/2007/wp-content/uploads/2007/09/op-diag-for-12-noon-july-25-1985-tokaido-and-sanyo-shinkansen-lines_sm.jpg

Operational Diagram for 12:00 noon, July 25, 1985 Tokaido and Sanyo Shinkansen Lines.

[bill937ca]

Bump!

I recently came across an example of a diamond.  The top part with red (express) and black (local) is for the Tokyu Den-en-toshi line and the bottom section is for the Oimaci Line.  Stations and the distances between stations are listed down the left side. You can see where express trains overtake local trains.

This diamond from a train simulation blog.

[Mudkip Orange]

Interesting.

Traffic engineers use almost the exact same system to figure out how to time signal lights.