Flashing signals

[Nick_Burman]

 

Why are the signals flashing in this clip? Power-saving measure? I've seen this happen several times before...

 

Cheers NB

[bikkuri bahn]

I believe that train is about to enter the Kanmon Tunnel.  Perhaps the signals are indicating a further speed restriction?

[miyakoji]

I've seen this before and thought it was actually a mismatch between the wavelength of the light from the LEDs in the signal and the camera's sensor.  So when they're out of phase, it looks like the signal is off, and when they're totally in phase, they look bright.  Maybe not. 

[Nick_Burman]

I believe that train is about to enter the Kanmon Tunnel.  Perhaps the signals are indicating a further speed restriction?

Indeed, the train is about to duck into the tunnel. But all three heads flashing at once? Including the red diverging aspects? And in synchrony, too. I doubt that it's a speed restriction, it would have been indicated in the same head. And it's not just in the entrance to the tunnel either... If you watch the Chitetsu cab ride I posted, you'll notice the same thing happening to signals on the parallel Hokuriku Main Line; there is one moment where the Chitetsu train is stopped when you can see this same phenomenon happening to a block signal on the JR tracks alongside.

 

Cheers NB

[bikkuri bahn]

Note how the platform number sign is also fading periodically (I assume fluorescent lamp).  However, the signal in the distance to the right shows no such behavior.

[ToniBabelony]

Most possibly the frequency of the LEDs that are not in line with the digital camera as miyakoji pointed out. The quality isn't that good, so that might explain the flashing.

 

EDIT: After watching it again: after the train has left, the signals stop flashing. So maybe it IS because of the tunnel and extra safety. Also, the signals don't seem to be LED types...

 

You know what? I'll ask a friend and former JR Freight train driver what's up with this.

Edited July 21, 2013 by Toni Babelony

[westfalen]

If it was something that applied only to that train only the signal that applied to the train should be flashing, even the ones on the far left are flashing. I've seen LEDs out of sync with my video camera in some of my videos and it's more of a flickering that what you see in this video, you're talking 50 or 60 cycles/second. The platform number sign fading in and out doesn't seem to always be in time with the signals either.

[marknewton]

If it were just one signal head flashing I would assume that it's an additional aspect or indication. We have signals here that can show a preliminary medium or caution turnout indication when that lamp is flashing. But I suspect that's not what we're seeing here. Be interesting to know what the answer is...

 

Cheers,

 

Mark.

[westfalen]

The platform number sign fading in and out reminded me of the time when I was assistant station master at Murphy's Creek at the bottom of the Toowoomba Range when CTC was being commisioned and colour lights replaced semaphores. One night the electricians were testing new flashing lights at the level crossing in the middle of the station yard and the guy living across the street came over and said the lights in his house were pulsating in time with the crossing lights, we then noticed the station lights were doing the same thing.

Edited July 22, 2013 by westfalen

[Nick_Burman]

Note how the platform number sign is also fading periodically (I assume fluorescent lamp).  However, the signal in the distance to the right shows no such behavior.

 

BB, thanks, I didn't notice the fluorescent lamp. Very odd indeed, especially because I noticed the same phenomena happening in two distinct locations (Moji in Kyushu and Namerikawa near Toyama) separated by hundreds of km...

 

Cheers NB

[tantousha]

I lived in Shimonoseki for a year back in 2009 and took the tunnel to work everyday. I can definitely say that I never saw flashing signals and especially not flashing platform signs... That said, it is definitely odd.

[miyakoji]

I'm posting this in another thread (http://www.jnsforum.com/community/topic/7773-miyakojis-bus-corner-volume-2/), but here's video of road signals that do this:

 

Osaka Municipal Bus - Route 86, Kintetsu Fuse to Hankyu Kami-Shinjō

 

 

I'm going back to my guess that it's an interaction between the light and the camera and that they don't flash [] !  Look at the green (blue!?) signal around 1:50, and a red signal around 3:55.  But, others don't seem to do this, and they're less bright overall.  Maybe older, conventional light bulbs versus LEDs?

[Ochanomizu]

Hello,

 

Please allow me to explain the use of flashing signals.

 

Firstly: traffic signals.  Many traffic signals in Japan have a countdown timer to indicate how much green or red time is remaining.  This is particularly useful if you have a red signal because you can turn off your car if you must wait a long time.  Many signals without a countdown timer will have a flashing red or green for the last 10 or 20 seconds of the cycle.  However, this flashing is about 1 second on and 1 second off.  The video above is different.  I think the signals go blank for a long period of time has something to do with the video camera.  You can see on the following video that the camera has a filter or other device that blocks out the light from the LED signals:

 

 

Second: railway signals.  I believe flashing railway signals that are otherwise operating correctly indicate some hazard on the line.  This could be maintenance crew, for example.  Unfortunately, we did not get to see what work is being carried out.  However, if you look to the right side of the screen on the original video at around 2:10 you will see someone climb onto the end of the platform.  This could be regarding maintenance although I think he is not wearing helmet and vest.

[westfalen]

We were watching some of my video from my trip to Japan in December at the model railway club meeting today on the big screen in a members home theatre and I noticed these 'flashing' signals at Higashi Monzen and Minatocho on the Keikyu Daishi Line. None of the other signals appear to flash and I can't recall whether or not I saw the flashing when I took the video.

 

[bikkuri bahn]

Keikyu uses flashing signals, but only on its main line between Shinagawa and Yokohama- it's the YGF indication, or "yellow-green flicker"- to indicate speed restriction at 105km/h [max line speed is 120km/h, indicated by green(shinkou)].  In this case on a low speed line like the Daishi, I think its a frequency issue of the signal and video equipment.

[ToniBabelony]

Further elaboration on Keikyū signalling in combination with their C-ATS system: http://mirai-report.com/blog-entry-149.html

 

Red = 停止 [Teishi], Stop (full stop);

Double yellow = 警戒 [Keikai], Warning (25km/h);

Yellow = 注意 [Chūi], Danger (45km/h);

Yellow + green = 減速 [Gensoku], Deceleration (75km/h);

Yellow + green flashing (YGF)= 抑速 [Yokusoku], Speed suppression (105km/h);

Green = 進行 [Shinkō], Advance (120km/h).

 

All trains may proceed at 120km/h on the Keikyū main line, except for the Wing (ウィング号), which has to stay under 110km/h to stay on pace and not encounter stopping signals. The Wing is a non-stop service from Shinagawa to Kamiōka and beyond, which does not halt on stations in between. This includes Kamata, Keikyū Kawasaki and even Yokohama station! http://www.keikyu-ensen.com/train/wing.jsp

 

Keisei uses a special double green aspect signal (高速進行 [Kōsoku Shinkō], High Speed Advance) for the Skyliner services on the Narita Sky Access route that allows for 160km/h operation. The single aspect green allows for 130km/h on the same route, as opposed to 120km/h on the rest of the Keisei/Keikyū network. This however only applies for the Skyliner services. Normal trains run 120km/h. Keisei N3050 type trains are however prepared for 130km/h operation, but due to the shared traffic operations with other trains -which are restricted to 120km/h, the proposed 130km/h operations are never run.

Edited January 20, 2014 by Toni Babelony

[kvp]

The common usage pattern for flashing signals is that only one light flashes and there is always at least one lamp lit. During the unlit phase of the flash, the aspect should be more restrictive. This ensures that if someone catches only a quick glimpse of the signal they can't see it as unlit or showing a higher speed than it's meant to show. Also, switching is nearly instant. The slow pulsing of the lights can come from having a 50Hz/60Hz phase difference with a short exposure time camera, AC lit signals and the interference pattern slowly wandering around. This is one of the reasons one should never use AC or unfiltered DC on a layout to light the signals, just well filtered DC.

[Sacto1985]

I think given the signals are more like "blinking" on and off at a slow rate, and that could indicate to the locomotive engineer there is a speed restriction imposed on the freight train when going through the Kannon Tunnel--may be no more than 70 km/h (43 mph) maximum?

[westfalen]

Further elaboration on Keikyū signalling in combination with their C-ATS system: http://mirai-report.com/blog-entry-149.html

 

Red = 停止 [Teishi], Stop (full stop);

Double yellow = 警戒 [Keikai], Warning (25km/h);

Yellow = 注意 [Chūi], Danger (45km/h);

Green over yellow = 減速 [Gensoku], Deceleration (75km/h);

Green over yellow flashing (YGF)= 抑速 [Yokusoku], Speed suppression (105km/h);

Green = 進行 [Shinkō], Advance (120km/h).

 

All trains may proceed at 120km/h on the Keikyū main line, except for the Wing (ウィング号), which has to stay under 110km/h to stay on pace and not encounter stopping signals. The Wing is a non-stop service from Shinagawa to Kamiōka and beyond, which does not halt on stations in between. This includes Kamata, Keikyū Kawasaki and even Yokohama station! http://www.keikyu-ensen.com/train/wing.jsp

 

Keisei uses a special double green aspect signal (高速進行 [Kōsoku Shinkō], High Speed Advance) for the Skyliner services on the Narita Sky Access route that allows for 160km/h operation. The single aspect green allows for 130km/h on the same route, as opposed to 120km/h on the rest of the Keisei/Keikyū network. This however only applies for the Skyliner services. Normal trains run 120km/h. Keisei N3050 type trains are however prepared for 130km/h operation, but due to the shared traffic operations with other trains -which are restricted to 120km/h, the proposed 130km/h operations are never run.

I have always thought the Japanese use of the green over yellow aspect goes against the basic fail safe rule of railway signalling, if the yellow light is out because of a blown bulb or other failure you are left with a green aspect (the least restrictive aspect that signal can display) and the driver of the train misses one warning stage on his way to encountering a red signal. A signal should always fail to a more restrictive aspect, on Queensland Rail, for instance we use the British four aspect signalling with the sequence of green/double yellow/yellow/red, if one light in a double yellow signal goes out it drops back to the more restrictive single yellow.

[bikkuri bahn]

Perhaps the usage of such an aspect is counterbalanced by the close spacing of signals, at least on Keikyu- the driver can see not only the proceeding signal, but the one following, in most cases.  Anyway, there is overspeed trip built into the ATS system. Each driver also knows the daiya by heart, so they know where the train should be at any point, as well as the movement of the proceeding train.  The uni-directional operation of Japanese railways also helps.

Edited January 20, 2014 by bikkuri bahn

[westfalen]

Each driver also knows the daiya by heart, so they know where the train should be at any point, as well as the movement of the proceeding train.

Running your train on the assumtion of where other trains should be according to the timetable is a recipe for disaster, might be a bit less dubious in japan though I still wouldn't want to ride a train driven by a driver operating on that premise.

 

Back to the original subject, I thought it was odd that in the 14 or so hours of video I took during the trip with the same camera these are the only two signals that appear to do this.

Edited January 21, 2014 by westfalen

[ToniBabelony]

From this video I recently watched, around 0:13:13, the train stops at Amagasaki sta. where two red lights are also 'flashing' in sequence and one other on the high signal on the right in another pattern. I assume this is also due to the camera not being able to record the frequency.

 

 

Also, I would like to spend a day at the end of the platform there. Just watching trains go by... xD

[miyakoji]

Running your train on the assumtion of where other trains should be according to the timetable is a recipe for disaster, might be a bit less dubious in japan though I still wouldn't want to ride a train driven by a driver operating on that premise.

 

Back to the original subject, I thought it was odd that in the 14 or so hours of video I took during the trip with the same camera these are the only two signals that appear to do this.

 

Isn't kvp's comment above correct on both points?

 

- west, my understanding is (was?) that each signal shows one aspect or another at all times, and if one lamp wasn't on, it meant that one was burned out, and all trains stopped.  I thought I had sat in a stopped train while signal work was done, I guess I am not remembering this correctly.  Or would this be true on JR?

 

- in this thread we may be having some misunderstanding about "flashing."  I should have written "pulsing" when discussing this before, as kvp did.  In Nick's original video, I'd still call that pulsing, although it's faster than what I've seen in other videos.  I still think in reality, those lamps were lit solid, and this is an interaction between the lamps and camera.  In the US, I've seen some flashing railway signals, and they flash fairly quickly, and it's clear on-off-on-off, they do not fade in and out.  Unbelievably, google has not turned up any information on this. :(

[Ochanomizu]

Hello Mr Tony,

 

I mentioned in my post below that this is not camera.  It is because of line hazard such as maintenance crew.  Please review your video between 00:12:12 and 00:12:39.  You will notice that the overhead signal does not flash at all.  If the flash was function of the camera surely it would apply to all.

 

http://www.jnsforum.com/community/topic/7680-flashing-signals/?p=85953

[westfalen]

Isn't kvp's comment above correct on both points?

 

- west, my understanding is (was?) that each signal shows one aspect or another at all times, and if one lamp wasn't on, it meant that one was burned out, and all trains stopped.  I thought I had sat in a stopped train while signal work was done, I guess I am not remembering this correctly.  Or would this be true on JR?

 

- in this thread we may be having some misunderstanding about "flashing."  I should have written "pulsing" when discussing this before, as kvp did.  In Nick's original video, I'd still call that pulsing, although it's faster than what I've seen in other videos.  I still think in reality, those lamps were lit solid, and this is an interaction between the lamps and camera.  In the US, I've seen some flashing railway signals, and they flash fairly quickly, and it's clear on-off-on-off, they do not fade in and out.  Unbelievably, google has not turned up any information on this. :(

If the yellow light in a signal that was supposed to be showing yellow/green was burnt out all you would see is a normal green aspect and you would not know anything was wrong until you reached the next signal and found an unexpected yellow aspect by which time you are one signal closer to the red and still travelling at track speed.

 

I still think the flashing is to do with the cameras, even if it was good practice to use running signals to warn of workers on the track they are not flashing fast enough to get a drivers attention in a hurry, if you look away at the right second you won't see it. Funny that Japanese NTSC cameras see it as well as my Australian PAL one though.