Block signalling question

[Nick_Burman]

Hi all,

 

I have a few questions on Japanese block signalling, especially on the smaller, rural interubans... first, I noticed that most of these smaller liness use 2-aspect signals (for example, on the Fukui Railway), rather than the more familiar 3-aspect ones. How are these set up in stations? Also, am I right in thinking that even when the line is set up with signals, Absolute Block working is in force? I've never seen pictures of intermediary automatic block signals on single-track Japanese lines, so I guess that Permissive working is not practiced in Japan. Lastly, how are the signals activated, track circuits or does it use the OHW as part of the circuit (as on the Pacific Electric in the US)?

 

I mentioned Fukui...I read in one of the LRTA booklets that the Fukui Railway is controlled by CTC - is this a "full" (with point motors on both ends of the siding) or an "economy" (with a point motor on one end and a spring switch on the other) installation?

 

More questions as answers arise...

 

 

Cheers NB

[bikkuri bahn]

Whoa, lots of questions.  2 aspect signals are used by lines with relatively low traffic levels.  I think the standard simple setup is a home signal located before the entry switch of the station, and a departure signal.  As for intermediate (in sense of between starter and home) block signals, apparently there were/are such signals, functioning as distant signals- perhaps for lines with higher traffic levels/speeds.  I think it's standard for signals to be activated by track circuits.  Some remote lines use electronic block system with a radio transmitter on each train, which emits a signal controlled by the driver to activate signals (this is used on the Hanasaki Line in Hokkaido between Higashi Kushiro and Nemuro).

 

As for the Fukui Railway, according to the wikipedia entry 3 aspect signals are indeed used for this line. In addition to the home and starter signals, repeater signals as well as call on and shunt signal types are used.  In sections where there is street running, road traffic signals are used.

 

Can't answer about type of CTC, sorry.

 

This website has a series of pictures where you can see some of the 3 aspect signals on the Fukui Railway, in addition to the 2 aspect ones, which seem to be mainly in the station limits. Click on the first link on the bottom to continue along the route:

 

http://tawamu.web2.jp/shindensha3/page024.html

 

This website has lots of pictures of 2 aspect signals, notably of diesel railcar private railways in the Kanto Area, among others:

 

http://nekosuki.org/landscape/index2/operation-signal.htm#00001

[Nick_Burman]

Thanks BB, so for example, in a arrangement with 2-aspect signals a train approaching a passing siding would first face a distant signal (which could show either a "approach" or a "clear" aspect), then a home at the entrance to the siding (showing "approach" or "stop", with possibly more than a single head, one for each exit) followed by a departure signal at the end of the siding (showing either "clear" or "stop"), correct? Would these signals be automatic or manual?

 

By intermediate signals, I mean intermediate automatic block signals, as used in single track lines in the US and fitted with "permissive" working. These would permit two or more trains to move in the same track in the same direction (separated by blocks and block signals) while holding opposing moves out of the way in a siding.

 

Several US interurbans used signalling systems based either on contacts fixed to the OHW and tripped by the passing of the trolley pole/pantograph (like the Nachod system) and others used the power return to trip the signalling. Since Japan copied/imported a lot of its early technology from the USA, I thought that it would be only natural for Japanese interurbans to follow the same arrangements, at least in their early years.

 

 

Speaking of shunt signals, do railways in Japan have the concept of "yard limits"? Or do shunting movements which need to occupy the main line temporarily have to have the block token (in the case of the use of a "staff" system) in possession before venturing out? How shunting would be handled (from a signalling point of view) in a small wayside station?

 

Cheers NB

[bikkuri bahn]

Nick, I'm on shaky ground here, signaling and train control is not my forte (I'm still learning myself), so I can only surmise for the most part here.

 

so for example, in a arrangement with 2-aspect signals a train approaching a passing siding would first face a distant signal (which could show either a "approach" or a "clear" aspect), then a home at the entrance to the siding (showing "approach" or "stop", with possibly more than a single head, one for each exit) followed by a departure signal at the end of the siding (showing either "clear" or "stop"), correct? Would these signals be automatic or manual?

 

Yes, that sounds right.  I think the signals are automatic, in that they are interlocked with the switches.  In semaphore days, the signals were worked by ground frames at the smaller stations.

 

By intermediate signals, I mean intermediate automatic block signals, as used in single track lines in the US and fitted with "permissive" working. These would permit two or more trains to move in the same track in the same direction (separated by blocks and block signals) while holding opposing moves out of the way in a siding.

 

Permissive working seems out of place in Japanese railway culture, which avoids such "on the fly" type of operations in deference to working strictly to the "daiya" or working timetable- as I understand it this type of working is prevalent mainly in North America, and then only with freight (probably for safety reasons).  The North American practice of holding freights in a passing siding somewhere on the main line is not so prevalent in Japan- most sidings are located in the station area.  On busier main lines, freights are restricted to the late hours or possibly off-peak hours so as not to interfere with the passenger trains pathing.

[KenS]

I can't speak to your original questions, as I've mainly researched urban commuter lines, which don't make much use of two-aspect signals (mainly using Red/Green or Yellow/Green as station entrance signals in some places, depending on whether through expresses exist).  I've learned quite a bit from BB's posts here.

 

But I can say a bit about Japanese signaling, with the caveat that non-JR lines may easily differ from what I know, which is JR-centric.

 

Japan used to allow working past a red signal under certain circumstances.  The wikipedia page on Japanese Railway Signals mentions this under its description of a "Red" aspect. Passing a red signal (not a permissive one, but a movment authorized by a station master) was a significant contributor to the 1991 head-on collision of two passenger trains at Shigaraki, which killed 42 people, as described by wikipedia. There's a Japanese-language wikipedia page that expands on the use of the "stop then pass" use of red signals.

 

Signalling even on some single-line routes, typically (but not exclusively) uses track circuits.  There are some nice photos on this page from the site of a Japanese hobbyist who was doing research to design his own model signals (I posted about his Youtube videos on the DCC forum recently).  Most of his photos are of two-track lines apparently, but there is some single track, with three-aspect signals, at the end.

 

However, while there's a good description of how track circuit systems work in issue 21 of Japan Railway Technology Review (see the article on Signaling Systems for Safe Railway Transport), the article also mentions briefly a system used on single-track lines where blocks are assigned to trains based on a radio signal transmitted by the engineer. Station entrance and exit signals are also at least partially under the control of the station master at staffed stations.

 

Since a major accident in 1963 involving a red signal, this one passed by accident at Yokohama, resulting in a three-way collision with 161 deaths, Japanese lines largely (perhaps all) use automatic stop (ATS) systems. The basic form of this uses a ground coil connected to the signal which the trains reads (magnetically) when it passes the signal.  If the signal is red, the coil is energized and trips the brakes on the train. There's a description of the Yokohama accident, also known as the Tsurumi accident, in a JRTR article on railway accidents in Japanese Railway Safety and the Technology of the Day (JRTR vol. 33).

 

Japan is also on the cutting edge of train signaling research, as this paper (PDF) on the development of new systems incorporating computers into the signal head itself, coupled with more sophisticated communications systems.  So, for example, a derailed train can report its condition and location, and trains on adjacent tracks can be stopped automatically, even if no sensor reports a problem on their track (I can't find the reference for that use now, but it was in some article I read).

[bikkuri bahn]

Thanks Ken, for the informative post. 

 

the article also mentions briefly a system used on single-track lines where blocks are assigned to trains based on a radio signal transmitted by the engineer.

 

When I lived in Nemuro in eastern Hokkaido, I often saw drivers removing radio sets from the cabs at the beginning and end of their runs on the Hanasaki Line.  I always wondered what this was, as I didn't see this done on the main lines.  Last year I saw an article about train control on JR Hokkaido, and a map showed that the Hanasaki Line is one of the few lines not under CTC/PTC control on the JR Hokkaido network.  I think this radio set contains the transponder to allow operation of switches and signals on this remote line (most of the stations are unmanned).  Of course, in the old days (JNR and early JR years), these more remote/light traffic lines used semaphore signaling and station staff manipulated the signals from ground frames- you can see the remnants of these ground frames at some of the older stations, typically an alcove next to the station master's office/ticket booth.