Motion-sensitive platform lighting

[Peter Mugridge]

Quite a few just dim, they don't go off entirely.

One thing I like doing if I have a long wait on a quiet platform is to see if I can stay still long enough to get the dimming to kick in...

 

[Ediswan]

Quite a few just dim, they don't go off entirely.

Even better, as a passenger. Modern lighting control systems can do either, it is down to the client to say what they want. Some want to save every penny on power consumption, others see a benefit in maintaining a minimum lighting level.

 

[Baxenden Bank]

Yes, a particular problem where I work; they switch off too quickly.

Perhaps a need for a different sort of 'motion detector'? (sorry... )

I accept your pun and I'll raise you five.

Rather there is a need for a lack of motions detector.

Taking the serious side of that point, it would be entirely possible to determine that there was someone sat in a waiting room, or on the platform, and not turn the lights off.

London Transport trialled software on the underground (if not installed) to identify if a person had been hanging around on a platform for too long (potential suicides waiting to do it). Similarly LIDOR* identifies objects which shouldn't be there at level crosssings and then releases, or not, the protecting signal. Having an image of what an empty waiting room looks like, scanning the room for deviations from that normal, then turning the lights off, or not, seems an achievable solution, especially now that we have wall to wall CCTV coverage of every aspect of everywhere. Might be useful for detecting suspect packages too.

Returning to toilet situation, you LIDOR scan at floor level for a toilet fitting (normal, lights off) and recognise feet alongside as the deviation which keeps the lights on.

*LIDOR - radar detection

 

[jon0844]

I'm not sure it would be worth the investment for lights, but technology to intelligently monitor level crossings or platforms, or indeed other parts of the railway, is a good thing. Not necessarily to rely on to actually make any sort of safety critical decision, but rather alert someone to manually check something of interest. Of course you need to make sure that once you have all of this tech, you don't just outsource the monitoring to a room somewhere in Mumbai...

I'm not sure how successful the cameras (with sensors and two way audio) at Welwyn North have been Besides motion sensing, there's no reason the footage can't be configured to have image analysis that can detect more than just movements. Does anyone know more about this?

 

[Annetts key]

Do many stations have this? I was at Westbury last evening and as I wandered down the platform, the lighting came on as I passed along it.

From what I can see, the railways appear to decided to fit this as standard now when fitting LED lights in place of conventional fittings. And it looks like it’s happening at small, medium and large stations.

Yes, I've been on a couple of stations where the platform lights 'bright up' as you approach them. Considering that they're LED lights where the difference in the already low current consumption must be negligible, are they worth it?

As well as reducing power consumption when the lights dim, it also significantly extends the lifespan of the LEDs.

Some station platform lights in Cornwall used to be on a timer and went off completely about an hour after the last train of the night was due then came on again before the first one next morning.

This was standard practice at unstaffed stations on Western Region during the time that BR existed. It may have been similar elsewhere. The lighting control cabinet would have a daylight sensor and a time clock. If it was dark and within the time set by the time clock, a contractor would be switched on, hence powering on the station lighting.

Hence in the middle of the day, the daylight sensor would prevent the lights from being switched on. Then as it got dark, the lights would come on. The time clock would switch the lights off at a time after the last booked passenger train. They would stay off until just before the first timetabled train of the morning. Then as the sun comes up, the daylight sensor would switch them off again.

I'd imagine the neighbours would be bit annoyed by the light coming on, going off, coming on... It's noticeable how much light there is at a major station such as Leeds overnight, even during the Christmas shutdown. I've often wondered who the lights are for when there is literally no-one around, not even station workers. The Southern Entrance closes at 10pm but remains lit when it could at least be partly darkened or given motion-sensitive lighting.

Some large stations, that are (or they were) normally open for 24 hours a day, or nearly 24 hours a day, may not have any automatic or user controlled switch gear. Why pay for something that is/was not required?

Besides motion sensing, there's no reason the footage can't be configured to have image analysis that can detect more than just movements. Does anyone know more about this?

The trouble with systems that try to detect objects or movement (or lack of) in a video image from a camera, is that it takes a lot of processing by a computer. No point saving money on lighting if you then use that very same amount of energy running the image processing system…

 

[Ediswan]

As well as reducing power consumption when the lights dim, it also significantly extends the lifespan of the LEDs.

True. Nobody really knows how long the current crop of commercial LED lights will last. There is a fair chance that, in many cases, they will last until the whole system is ready for replacement. Like fluorescent, they do dim somewhat over time. The fix for this is to specify a system that 'as new' only needs 70-80% for full design brightness and gradually ramp that percentage up over the years.

The trouble with systems that try to detect objects or movement (or lack of) in a video image from a camera, is that it takes a lot of processing by a computer. No point saving money on lighting if you then use that very same amount of energy running the image processing system…

As you note, it is a balance. Personally, I expect the balance to swing in favour of using image recognition. Equally, I would not be surprised if some bright spark added image recognition to a lighting control system and neglected to allow for the 'parastic' power requirement.

 

[Parallel]

I think dimmable LED lights have been rolled out to most GWR stations now. I find it strange watching them all get brighter as the train runs down the platform. I wonder if they are distracting for drivers?

Bradford-on-Avon has older fluorescent tube lighting under the canopies but smart LED lighting at the far end of the platform that was installed when the platform was extended. Previously to this, there was no lighting beyond the footbridge, meaning half the platforms weren’t lit.

 

[Annetts key]

I don’t think the stations that were upgraded with the earlier design of LED lighting have motion detectors and dimmable LED fittings.

And there are certainly still plenty of stations that have relatively new fluorescent tube light fittings, or high pressure sodium fittings.

I think it will be a quite a while before stations with relatively new fluorescent tube light fittings have them replaced.

It will be a lot faster for the sodium fittings, as replacement lamps become more expensive and harder to get as the number of lamps made falls.

 

[skyhigh]

Northern are going through a programme of replacing the lighting at all stations they manage with new LED units, some of which have motion sensors.

 

[Mikey C]

Brussels is also where I came across smart escalators; they appeared to be very common across the metro/tram network. It seems an eminently sensible idea to me as an energy saving measure where escalator use is infrequent.

I'm pretty sure the Stockholm underground had them over 30 years ago

 

[LSWR Cavalier]

One thing I like doing if I have a long wait on a quiet platform is to see if I can stay still long enough to get the dimming to kick in...

Very good. If I have a wait, especially in the cold I walk to the platform ends, perhaps the lights would follow me, switching off behind.

Smart escalators were mentioned, do some stop altogether? I have seen some going slowly, they go to normal speed when someone steps on.

What about LCD lights, apparently they use little energy, but what is the payoff for that? Do they cost a lot to install?

 

[Annetts key]

What about LCD lights, apparently they use little energy, but what is the payoff for that? Do they cost a lot to install?

I presume you mean LED (Light Emitting Diodes - a type of semiconductor component that produces light when an electrical current passes through it with the correct polarity)?

Only LCD means Liquid Crystal Display (invented in the U.K.) which blocks or passes different polarisations of light, but does not produce light. Hence behind every LCD there is either a reflector or a back light.

LED lights are more efficient than most other human made light sources for an equivalent light output. If designed and manufactured correctly, they should have a lifespan of in excess of ten years. Although the light intensity will fall gradually by a small amount each year on average.

I don’t know about the cost of the fittings used by the railway, but the Chinese made ‘street lamps’ that can be got from online trading sites is reasonable. Although how reliable and how long these will last is another question…

Hopefully the railway is buying good quality light fittings. If they are, and they do have a long lifespan, that “should’ reduce maintenance costs, as then you don’t have to pay for maintenance staff to replace the lamp (“bulb”, not fitting) when it expires.

But only time will tell. It’s a similar story with road and street lights.

 

[Mikey C]

Smart escalators were mentioned, do some stop altogether? I have seen some going slowly, they go to normal speed when someone steps on.

I don't recall seeing a smart escalator stop altogether, I guess it would be considered dangerous if people get on thinking it's broken and won't move

 

[jon0844]

I don't recall seeing a smart escalator stop altogether, I guess it would be considered dangerous if people get on thinking it's broken and won't move

I prefer those that stop and then start before you've stepped on over those that go slow and speed up as you're on it.

I don't think I've seen the type that stop entirely here, and it took a while abroad to realise that escalators weren't broken. They usually have animated green arrows to show they're on (and which direction they'll move in) and no entry if not working or the wrong way.

 

[The exile]

I don't recall seeing a smart escalator stop altogether, I guess it would be considered dangerous if people get on thinking it's broken and won't move

Plenty of German ones did over 30 years ago - but as someone has mentioned, they need “ stop / go” indicators so you don’t head for the wrong one / one that is broken (although they were usually obvious because of where the litter was)

 

[Peter Mugridge]

I prefer those that stop and then start before you've stepped on over those that go slow and speed up as you're on it.

I don't think I've seen the type that stop entirely here, and it took a while abroad to realise that escalators weren't broken. They usually have animated green arrows to show they're on (and which direction they'll move in) and no entry if not working or the wrong way.

I've seen and used plenty of those in Paris.

 

[LSWR Cavalier]

I presume you mean LED (Light Emitting Diodes - a type of semiconductor component that produces light when an electrical current passes through it with the correct polarity)?

Only LCD means Liquid Crystal Display (invented in the U.K.) which blocks or passes different polarisations of light, but does not produce light. Hence behind every LCD there is either a reflector or a back light.

LED lights are more efficient than most other human made light sources for an equivalent light output. If designed and manufactured correctly, they should have a lifespan of in excess of ten years. Although the light intensity will fall gradually by a small amount each year on average.

I don’t know about the cost of the fittings used by the railway, but the Chinese made ‘street lamps’ that can be got from online trading sites is reasonable. Although how reliable and how long these will last is another question…

Hopefully the railway is buying good quality light fittings. If they are, and they do have a long lifespan, that “should’ reduce maintenance costs, as then you don’t have to pay for maintenance staff to replace the lamp (“bulb”, not fitting) when it expires.

But only time will tell. It’s a similar story with road and street lights.

Traditional lights produce a lot of heat that is generally wasted. Is that the secret, that LEDs convert energy better and produce less heat? I thought it was a law of engineering and electrics that improvements usually have downsides (cost, weight etc).

 

[fkofilee]

Redhill have them.

 

[Annetts key]

Traditional lights produce a lot of heat that is generally wasted. Is that the secret, that LEDs convert energy better and produce less heat? I thought it was a law of engineering and electrics that improvements usually have downsides (cost, weight etc).

Yes, LEDs produce less heat. Hence are more efficient. That’s why most torches (flashlights) will run for longer on the same set of cells (battery) compared to a traditional filament lamp torch for example.

The downside is that when run from a 240V (230V) mains supply, a far more complex electronic ‘driver’ is needed compared with other lamp types. Because of it’s complexity, if it’s not designed well, or not manufactured from good quality components, it may fail before the LEDs do.

This is the reason you sometimes see LED lights flashing.

 

[Ediswan]

Traditional lights produce a lot of heat that is generally wasted. Is that the secret, that LEDs convert energy better and produce less heat? I thought it was a law of engineering and electrics that improvements usually have downsides (cost, weight etc).

Luminous Efficacy, lumens of light output per watt of energy input, is usefully better for LEDs than previous technologies.

https://en.wikipedia.org/wiki/Luminous_efficacy#Lighting_efficiency

The majority of the energy input is still wasted as heat though. But as you don't need to put so much energy in, you get less heat out. A typical 40W LED ceiling tile still generates around 30W of heat. Failure to handle that heat properly is one reason poor quality LED lights can fail early.

 

[jon0844]

Yes, the electronics are nearly always the cause of failure for a LED lamp (although early generation LEDs were pretty poor and faded very quickly, but modern bulbs aren't anything like this).

For professional lamps (like street lights) the LED driver is usually an easily replaced part, but for home bulbs it is almost always not going to be easy or possible to fix a bulb. Again, most bulbs simply won't fail and probably last for longer than their rating because the tech has advanced considerably - reducing heat, or dissipating it very effectively.

You can still find crazy bright lights on eBay and the like, which are often shown to have all sorts of problems, but some of these are borderline dangerous and I doubt most people would ever buy one (but it's always fun to see some YouTuber trying to light up a mountain or something, or bigclivedotcom taking one apart to show how badly constructed they can be).

 

[janahan]

Lot of interesting information here, but I thought I would wade in, as having studied a lot about LED lighting. Firstly, many (maybe most) manufacturers of LED bulbs are actually cheating us. They created LED "Bulbs" (should actually be called systems, as they consist of more than one element), that are often "overdriven". This means that rather than having the correct number of elements for the expected Voltage/Wattage/Lumen output, they often have fewer elements, mainly for cost (and as you will see, other reasons).

The biggest culprits are the "string" LED lights, thatlook like traditional filaments. So instead of fitting say 20 individual elements, they would perhaps fit only 15 or even less, and then overdrive it to give the same light output as a 20 element bulb. This does make it cheaper to manufacture, but has the downsides that it generates significantly more heat, and also reduces the lifespan by a similar manner. All the quotes on LED "lifespan" usually assume the bulbs are not overdriven, and also assume the bulb is not switching on or off regularly, which does impact lifespan (note the rapid switching off/on thousands of times a second using PWM for dimming purposes is not as harmful if done right).

The cynic in me, woudl suggest that manufacturers are pruposefully overdriving the bulbs to a) cheap out, and b) reduce the lifespan so that more are purchased. It seems that I was not the only one who thought that, as Dubai's ruler (Sheikh Mohammad Bin Rashid Al Maktoum) was tech savvy enough to have cottened onto this tactic, and put into law certain rules about LED bulbs, with the key edict that they should NOT be overdriven like this, and instead slightly underdriven to better efficiency, colour, and lifespan. Big Clive on You Tube investigated the Philips Dubai bulb against a normal Philips LED bulb. The first thing he noticed was that the dubai bulb had more elements for the same lumens, however, used significantly less actual power, and generated less heat overall, inferring a longer lifespan.

LED bulbs are also a lot more linear in power usage when diming; incandescents at 50% brightness still need more than half power, plus the use of resister packs vs PWM also increase the power used to the point that on some setups a 50% dimming can use almost the same amount of power as full on, with the only advantage being longer life for the bulb.

Going back on topic, it is better to actually dim down LED bulbs than turn them off when there is a high incident of movements, as a cold start on LEDs to full brightness can put a lot of stress on the components, with dimming (despite dimming actually causes the bulb to switch on and off thousands of times a second) being significantly less stressfull with the proper drivers. The problem is many lighting setups are designed for incandescents so cannot effectively (or properly) dim LEDS nece the reason why they switch on and off. Dedicicated LED motion control cuircuits can dim, and also can intelligently dim too based on the type and frequency of movement.

 

[Annetts key]

Lot of interesting information here, but I thought I would wade in, as having studied a lot about LED lighting. Firstly, many (maybe most) manufacturers of LED bulbs are actually cheating us. They created LED "Bulbs" (should actually be called systems, as they consist of more than one element), that are often "overdriven". This means that rather than having the correct number of elements for the expected Voltage/Wattage/Lumen output, they often have fewer elements, mainly for cost (and as you will see, other reasons).

The biggest culprits are the "string" LED lights, thatlook like traditional filaments. So instead of fitting say 20 individual elements, they would perhaps fit only 15 or even less, and then overdrive it to give the same light output as a 20 element bulb. This does make it cheaper to manufacture, but has the downsides that it generates significantly more heat, and also reduces the lifespan by a similar manner. All the quotes on LED "lifespan" usually assume the bulbs are not overdriven, and also assume the bulb is not switching on or off regularly, which does impact lifespan (note the rapid switching off/on thousands of times a second using PWM for dimming purposes is not as harmful if done right).

The cynic in me, woudl suggest that manufacturers are pruposefully overdriving the bulbs to a) cheap out, and b) reduce the lifespan so that more are purchased. It seems that I was not the only one who thought that, as Dubai's ruler (Sheikh Mohammad Bin Rashid Al Maktoum) was tech savvy enough to have cottened onto this tactic, and put into law certain rules about LED bulbs, with the key edict that they should NOT be overdriven like this, and instead slightly underdriven to better efficiency, colour, and lifespan. Big Clive on You Tube investigated the Philips Dubai bulb against a normal Philips LED bulb. The first thing he noticed was that the dubai bulb had more elements for the same lumens, however, used significantly less actual power, and generated less heat overall, inferring a longer lifespan.

LED bulbs are also a lot more linear in power usage when diming; incandescents at 50% brightness still need more than half power, plus the use of resister packs vs PWM also increase the power used to the point that on some setups a 50% dimming can use almost the same amount of power as full on, with the only advantage being longer life for the bulb.

Going back on topic, it is better to actually dim down LED bulbs than turn them off when there is a high incident of movements, as a cold start on LEDs to full brightness can put a lot of stress on the components, with dimming (despite dimming actually causes the bulb to switch on and off thousands of times a second) being significantly less stressfull with the proper drivers. The problem is many lighting setups are designed for incandescents so cannot effectively (or properly) dim LEDS nece the reason why they switch on and off. Dedicicated LED motion control cuircuits can dim, and also can intelligently dim too based on the type and frequency of movement.

Further to this from janahan, I’ll add the following:

Unfortunately with lots of consumer products, especially those sold via trading sites, deliberate and misleading “information” combined with a low-ish price is used to attract sales. The manufacturer, distributor/seller and trading platform don’t care about reliably, quality, lifespan, consumer rights etc. As even if you do discover that you’re been had, either they’ve disappeared, it’s been too long time wise or are willing to cover the cost of a refund, with them taking the gamble that most people won’t bother to complain or claim.

As always, be careful if the price or details are ‘too good to be true’. If there is a lack of quality control, such as on trading sites, a LED lamp may actually consume half or less of its stated power rating (Watts or W) because either it’s been deliberately mislabelled/described or because they’ve cheaped out on the LED driver electronics.

Or there may be inadequate heat sinking / airflow / ventilation (LEDs last longer if they are kept within the recommended operating temperature range, they last longer if they are run at a lower temperature). If the LED chips and/or the driver electronics runs too hot, this will shorten the lifespan.

Running any LED at less than it’s maximum rating (power) will extend its life both by reducing the heat level and because there is less stress of both the semiconductor junction and the phosphor. The efficiency is also better compared to when it’s run at higher power levels.

Over time, the light output of all LEDs gradually reduces. Even a low power indicator LED will become dim after 25 to 30 years of operation.

There are many different manufacturing methods used in the construction of LED lamps and fittings. I would not say that the ‘filament’ (“string”) types are any better or worse than the other LED technologies.

There are some very good quality LED lights and LED fittings available. But with a lot of consumer market LED lamps, the lifespan ratings are only valid if the lamp is only run for three hours a day at most. Not continuously. Industrial lamps (which of course cost more) are often specified for continuous operation.

Linear is a bit of a “QI klaxon” word for me. The electrical characteristics of a LED are highly non-linear. They are current operated devices, but only conduct any significant current when the forward voltage is above the ‘turn on’ voltage (which for a blue or white individual LED is between 2.5V and 3.1V approximately). Further, the light output is also not a linear curve compared to the input power.

Although, the other light sources (including tungsten filament, quartz halogen, and the various gas discharge lamps like fluorescent tubes and sodium lamps are also very non-linear.

If properly designed, there should be no problem with switch on/off/on cycles. A good quality LED lamp/fitting should far outperform other lamp types in this respect. In actual fact, in applications where lamp life is important, tungsten or quartz halogen filament lamps are only dimmed when “flashing”, rather than actually being switched off completely.

For reasons of efficiently, pulse width modulation (PWM) or similar techniques are often used to control the brightness of LEDs. Indeed, if you have an alarm clock that uses LED seven segment type display, the individual LEDs are multiplexed to reduce the complexity of the interconnections. This is a form of PWM.

Obviously if the design is poor, then the switch on “surge” will eventually result in early failures.

Existing dimmers for tungsten or quartz halogen filament lamps are specificity designed only for this type of lamp. They take advantage that a hot metal filament takes time to change temperature (and hence light output). They use phase angle control.

Although there are some LED lamps that claim to be compatible with these ‘conventional’ dimmers, the performance is not exactly good.

If you want to have a dimmable LED lamp, change the dimmer switch to a conventional on/off switch and buy a remote controlled LED lamp with built in dimming functionality.

 

[skyhigh]

Sorry, off-topic for station lighting but relating to quality/durability I'm sure the replacement LED lamps on 333s are gradually getting dimmer. They're on for the majority of the day so I wonder if they were specced for that use or not... Quite a few are starting to flicker now too.

 

[jon0844]

Sorry, off-topic for station lighting but relating to quality/durability I'm sure the replacement LED lamps on 333s are gradually getting dimmer. They're on for the majority of the day so I wonder if they were specced for that use or not... Quite a few are starting to flicker now too.

I think it was National Express that fitted LEDs on the HSTs or MK4s and they were cool white (not the best look for a 'cosy' train) and dim from day one. The vestibules were stupidly dark.

Some really poor retro-fit LED lights were trialled on a single 313 by GN and they were also half the brightness of the standard tubes.

Thankfully, as you can see from a class 700/717, they can be very nice indeed - with different brightness levels (717s defaulting to a dimmer brightness level, which can be very nice at night but is perhaps too dim in the day).

Trains should have warm lights IMO, while platforms definitely benefit from cool white.