Why don't new locomotives have L.E.D. headlights? Aren't they brighter and last longer? Thanks for any replies.
New GE ES44ACs are coming with LED numberboards. I think the headlights are not.
I suspect they don't so that they don't become obscured with snow and ice.
Just my thoughts too. At least looking at Innotrans 2012 locomotives (the worlds biggest railway expo in Germany) there were only two where the led lights were accepted: these locomotive do not need strong headlight running suburban Swiss traffic. Or doing mostly local switching for that matter.
ndbprrI doubt they are capable of producing sufficient light at this time.
But as you see here is the normal case on Siemens mobility ES64F4, lots of leds as tail light and none on headlights.
At this point in time LED's are good, but not quite good enough. No matter what the close-up intensity is they can't throw a beam like an incandescant lamp.
Compare an LED flashlight to something like a Mag-Lite and you'll see what I mean.
Apparently you haven't seen an LED Mag-Lite, I've got one with two D cells and it significantly outshines my three D cell incandescent Mag-Lite.
- Erik
I think the technology is just becoming affordable.
In Australia, Pacific National are rebuilding their Cv40-9i locomotives, effectively low clearance export versions of the Dash9 44CW with new 7FDL16 engines after 16 or so years in service.
These are all being fitted with LED headlights that appear as bright as the previous dual sealed beam headlights, if somewhat bluer in colour.
This was illustrated in Railway Digest Magazine, October 2013 issue, pp30-31 but the headlights are the same size as the sealed beams but are hexagonal in shape made up of an array of led elements.
About a year ago Countrylink power car XP 2004 was fitted with three such headlights in place of the three sealed beams originally fitted.
In each case these replaced standard sealed beam headlights.
M636C
No one has commented on what I said yet, but it's been an issue in other instances where LED's have been used in replacement of traditional incandescent bulbs outdoors in Northern regions. So it's very likely playing some factor here although I concede that it very well isn't the primary reason.
Both street lights and stop lights come to mind where installations have suffered during winter months where as traditional technology produces its own heat to keep the fixture free of snow and ice. As I understand it, many municipalities fooled by the initial savings are finding them rather maintenance intensive when they have to have an employee out there cleaning them by hand. And I'm sure that some are retrofitting them with heating elements and such.
I'm sure that the durability of LED headlights is attractive, but this is going to be at least one factor that they're going to have to deal with if they haven't already before you have a chance of them seeing widespread adoption here. I suspect that HID lamps like airlines have been switching to for their landing lights are the future for locomotive headlights though rather than LED.
http://en.wikipedia.org/wiki/High-intensity_discharge_lamp
Incidentally, Tornado's headlight (Which this class like most British locomotives didn't carry when originally in service) is LED. So there's another one.
I live in the Northern Europe and cities here are actually in a process of chancing most outdoor street lighting to use leds. The process is somewhat slow at the moment, but gaining momentum every time the led prices drop with the light production ramps up.The illumination power with leds is quite good on the street lamps, but the effective electricity usage length and the servicability much better than on earlier models.
Great thinking about the problems created by reduced warming effect. Here in the extreme North the ledlights still seem to produce enough heat to keep the moisture off however, leaving the birds warming themselves up on top of the lamps be the only sufferers. Many people enjoy the warm tones of the current multimetal etc. lamps produce but as far as I know leds come in multiple tones, so this should not really be a problem. Here it is not the cities leading the led revolution, they are actually trailing what the homes have already done by switching to leds. Also looks like the usage of leds in cars is already creeping from back to the front and maybe pretty soon all the way to the headlights too...leaves a short stretch to span all the way to multiple units and locos.
Leo_Ames No one has commented on what I said yet, but it's been an issue in other instances where LED's have been used in replacement of traditional incandescent bulbs outdoors in Northern regions. So it's very likely playing some factor here although I concede that it very well isn't the primary reason. Both street lights and stop lights come to mind where installations have suffered during winter months where as traditional technology produces its own heat to keep the fixture free of snow and ice. As I understand it, many municipalities fooled by the initial savings are finding them rather maintenance intensive when they have to have an employee out there cleaning them by hand. And I'm sure that some are retrofitting them with heating elements and such. I'm sure that the durability of LED headlights is attractive, but this is going to be at least one factor that they're going to have to deal with if they haven't already before you have a chance of them seeing widespread adoption here. I suspect that HID lamps like airlines have been switching to for their landing lights are the future for locomotive headlights though rather than LED. http://en.wikipedia.org/wiki/High-intensity_discharge_lamp Incidentally, Tornado's headlight (Which this class like most British locomotives didn't carry when originally in service) is LED. So there's another one.
Here is a new Värmlands trafik X53-2 with both rear lights (now on) and the running lights using led technology while the brightest set of lights is still based on the traditional lighting technology.
Firelock76 At this point in time LED's are good, but not quite good enough. No matter what the close-up intensity is they can't throw a beam like an incandescent lamp...
At this point in time LED's are good, but not quite good enough. No matter what the close-up intensity is they can't throw a beam like an incandescent lamp...
You have evidently not seen real high-power LEDs up close. They are not little encapsulated beads of plastic with leads.
The big issue with using power LEDs in place of present headlight bulbs or HID is probably still first cost, with a strong backup reason being the size and complexity of the heat-sinking means needed to keep high-power LEDs working. Glass-envelope bulbs can be run happily at very high temperature. LEDs -- no. Look at any of the current generation of light-bulb replacements to see some of the approaches required.
The other point is that LEDs don't provide a good point source suitable for focusing via parabolic reflector (as many current headlight arrangements are constructed). You may have seen some approaches that try to approximate this (they sometimes look like little 'corncobs') but again these can be highly limited by the heat-sinking approach (generally a heat pipe of some sort at the business end) that is needed to get high areal emitted flux and good focus in the beam. Instead you need a flat array of elements to form a comparable beam, and that also increases the cost.
I expect the same thing will be true of LED headlights on locomotives as appears to be true of LED headlights on automobiles -- they will consist of a large number of separate emitting elements distributed across the structure, and not a bunch of dies in the hole that previously held a bulb or a couple of sealed-beam lamps. But the cost has to come down some more before they'll be cost-competitive with, say, a high-voltage HID replacement for a 74V incandescent bulb setup...
erikem Apparently you haven't seen an LED Mag-Lite, I've got one with two D cells and it significantly outshines my three D cell incandescent Mag-Lite. - Erik
Oh, no doubt LED's can be pretty intensive. I've gotten a face-full of LED light so I know. My qustion is just how far can it throw that light compared to an incandescant lamp.
An example: I've got a car inspectors lantern, old 6 volt technology, that will throw a beam 100 yards easily. No LED flashlight I've got can do that, but for "up close and personal" lighting the LED's are fine.
The point I'm trying to make is a headlight on a locomotive has to throw that beam far down the line so the enginemen can see what's in front of them, and so others trackside can see there's a train coming. Can an LED array do that? If so, great! I'm not one to stand in the way of progress. If it can't, then we can see the reluctance to accept total LED implementation.
The Amtrak ACS-64 has LED headlights and ditch lights, it will need to be seen if snow won't obscure these, as they do not give heat to melt snow on them.
Well, we have to find out from the experience don't we? The LEDs still emit a lot of heat, being high powered leds. Unless Siemens mobility says otherwise. They have a formidable research organization finding out about railroading in the colder climates, something competitor Bombardier has been unable to do on their TRAXX product line, so I'm quite confident using LEDs will be no problem. Besides Siemens mobility is very much oriented towards quality where much of the competition is oriented towards the cheap price. Meaning that by paying a slightly higher price you get a well working solution for decades. And sometimes something quite new like using leds here.
Dutchrailnut The Amtrak ACS-64 has LED headlights and ditch lights, it will need to be seen if snow won't obscure these, as they do not give heat to melt snow on them.
But are they really leds? Looks like the middle section of the lights have formidable lenses (go to 4rail.net or Siemens site or maybe easiest, just see the latest Trains magazine to see the larger picture than here). If I'm guessing correct, this lens would not be needed if the light was not LED or laser? Picture courtesy of Siemens mobility.
McKeyLooks like the middle section of the lights have formidable lenses (go to 4rail.net or Siemens site or maybe easiest, just see the latest Trains magazine to see the larger picture than here). If I'm guessing correct, this lens would not be needed if the light was not LED or laser?
You still want a lens to form the beam desired. (Little LED arrays have the lenses 'built into' the individual packages, but their intent when used on vehicles is usually more to imitate a Fresnel lens than to form a collimated beam.)
I'd expect that the lens is somewhat anamorphic compared to the equivalent for incandescent/halogen or HID lighting, as the planar area of the emitters doesn't focus neatly with a simple parabolic reflector. Be interesting to have someone from Siemens, or with firsthand experience of the ACS-64, chime in on this design detail.
[Oh, yes: Lasers at the required illuminating power would be dangerous if excessively collimated, and prone to nasty speckle if dispersed; there is also some issue with problems of accidental reflection or even momentary focusing at the wrong point. Noncoherent, broad-spectrum light is still the wiser choice for general illumination, I think. In situations where you're using synthetic-vision and sensor-fusion techniques, lasers have their uses ... but better vision sensors have far more... ]
But can't you disperse the laser light. I've read they are the alternative for lighting with leds and the two are campaigning which is the more energy effective.
And yes, I know the hazards of the lasers we are normally accustomed to 'see'. This laser must be some sort of nonfocusing beam of light? Just read it on the science news comparing the two's effectiveness, no real experience of this kind of new lasers myself. But since I'm using LEDs every day for lighting, maybe the lasers will be here in just a few years.
Overmod [Oh, yes: Lasers at the required illuminating power would be dangerous if excessively collimated, and prone to nasty speckle if dispersed; there is also some issue with problems of accidental reflection or even momentary focusing at the wrong point. Noncoherent, broad-spectrum light is still the wiser choice for general illumination, I think. In situations where you're using synthetic-vision and sensor-fusion techniques, lasers have their uses ... but better vision sensors have far more... ]
Lasers are more energy-effective but used as such are still narrowband-emitting devices. And dispersing the beam brings up speckle as a concern...
A far more likely thing to be used for locomotive lighting would be the approach described in patents 7435982 and 8309943; Energetiq, the assignee, is currently producing very high output broad-spectrum lighting devices that use this principle. Whether the production device uses a (different) laser to generate the plasma is unclear. Note that the light emitted is NOT coherent, but is in a 3D region that can be placed at the focus of appropriate optics for reasonable beam generation and shaping.
There are reasons why the similar sulfur-lamp technology hasn't been pursued for locomotive applications!
Since modern technology for the pumping lasers (e.g., fiber or disk) is over 30% efficient, electrical to optical, it is possible for comparatively low wattage to generate very high-quality light, and an approach of this kind is almost certainly superior to trying to use direct laser emission, from something like VCSEL or VECSEL arrays, for lighting in a manner similar to the approaches being used for LED lighting. Compare the physics involved in HID lighting, which involves a different (and probably less energy-efficient) method of excitation.
I upgraded a 3D cell Maglite and a 2 AA cell Mini Maglite both circa 1980 to LED and they're both a lot brighter and have better battery light. But my newer LED based mini Maglite (2AA) is brighter then the upgraded mini.
I would agree that high wattage / lumens LEDs are still somewhat limited but LED headlights will gradually become far more common as a way of reducing power consumption and therefore increasing fuel mileage.
Halogens may take the place of incadescent lights. They are brighter.
Halogen lights are incandescent lights. They just use halogen gases and hi-temp glass in the enclosure because they run hotter (and brighter). Some of them emit 'light' in undesirable wavelengths and must use special filtering lenses.
Here's a good opportunity to explain the difference between "Lumens" & "Candlepower". Lumens is a measurement of how much light is actually produced by a light source. Candlepower is a measurement of the concentration of the light, the ability "to throw that beam far down the line". Obviously a locomotive needs high values of both.
Pacific National NR class Dash 9's are being retrofitted with LED Headlight and Ditch lights, and yes they are far brighter and have a better throw than the old 350w beams. They also seem easier on the eye, less tiring than the older lights, could be the color spectrum used.
Talking about blinding crews...
Mechanical Department "No no that's fine shove that 20 pound set all around the yard... those shoes aren't hell and a half to change..."
The Missabe Road: Safety First
Here's a good opportunity to explain the difference between "Lumens" & "Candlepower". Lumens is a measurement of how much light is actually produced by a light source. Candlepower is a measurement of the concentration of the light, the ability "to throw that beam far down the line".
But isn't lumens/~12.57 (from spherical geometry) = cp? (converting units between English and 'metric' as desired; it seems nobody still converts cp to .981 candela any more so I leave this also to readers with a perfectionist bent...)
In any case, we shouldn't be caring nearly as much about irradiance as we do about illuminance. So here, wouldn't lux (an incident lumen per sq. meter) be a more appropriate unit for beam 'power'? [Yes, you would need a reference target, but converting this to visibility of important features in a typical locomotive crew's 'sight picture' is not particularly difficult.]
(We could have a long, long discussion about the wascally ways that manufacturers define 'beam candlepower' at whatever the brightest spot of their beam is, which really isn't worth anything except marketing/advertising advantage. On the other hand, I'd prefer we not.)
Amtrak's new ACS-64s have LED headlights and ditch lights, much to the consternation of photographers catching their debut runs. They seem to always be getting at least one of the four when it is in its off cycle!
Audi is replacing LED technology with laser diode technology. It will debut at the 24 Hours of Le Mans later this year and is planned for street cars.
So perhaps it's the sign of the future.
Headlights are more complicated than just brightness.As others have noted there does need to be enough heat to melt snow.. But there also needs to be consideration of color tempurature and spectrum. Many LED lights have blue-light and very narrow spectrum emission.. This can cause problems with visability... It may blind someone, and not allow people to see cearly at the same time.We should select lights that have similar light properties as conventional Halogen lights.There are also problems with projector housings and other beam shaping techniques that hides the light so people cannot see the lamp... then it blinds them, or it appears to be flashing because of subtle variation in direction where it is pointing. You can see this on the highway with these cars with fad lighting that is super dangerous. We must not point dangerous lights at other people.. and note when they are not pointed correctly and are of narrow spectrum they don't help us see... they may make us think they are bright, but they don't actually help us see anything.
AirOp Headlights are more complicated than just brightness.As others have noted there does need to be enough heat to melt snow.. But there also needs to be consideration of color tempurature and spectrum. Many LED lights have blue-light and very narrow spectrum emission.. This can cause problems with visability... It may blind someone, and not allow people to see cearly at the same time.We should select lights that have similar light properties as conventional Halogen lights.There are also problems with projector housings and other beam shaping techniques that hides the light so people cannot see the lamp... then it blinds them, or it appears to be flashing because of subtle variation in direction where it is pointing. You can see this on the highway with these cars with fad lighting that is super dangerous. We must not point dangerous lights at other people.. and note when they are not pointed correctly and are of narrow spectrum they don't help us see... they may make us think they are bright, but they don't actually help us see anything.
The general change to LED lighting was made in Australia five years ago (see my post earlier in this thread from 2013). 120 locomotives that work maybe two thirds of all intermodal trains in Australia have had LED headlights for five years.
They are easier to see in the distance. I have heard of no problems with the illumination from the crews, so they must be able to see objects as well as with incandescant lights. The lights don't appear to have a dim setting as did the old sealed beams.
In Australia, railways might experience snow once in ten years and then in very restricted areas, so heat to melt snow isn't important.
So I think LED lights avoid the problems you are describing.
Peter
There are a couple of different issues being brought up here.
In order to conserve power (and some electrical 'driver' expense) some LED installations 'multiplex' power to the individual diodes, much as older digit displays did to individual numbers or segments. (Quickly move an older alarm-clock display in the dark in your peripheral vision to see the effect.) This is what I think produces the 'disappearing headlight' effect on the ACS64s and other contemporary locomotives. It is of very little consequence to human vision, as the persistence of vision is far longer than CCD 'shutter' times, but it is probably important in the design of things like outward-facing cameras that are expected to work effectively.
Some of the deleterious effects of pseudowhite LEDs have been overcome with the inclusion of short- to long-acting phosphors in the diode module construction -- this is, for example, one way the new generation of 'warm white' home bulbs gets a better perceived color temperature. The result may still be excessively 'peaky' in spectrum but overcomes at least some of the selective color rendition issues that are technically present with pseudowhite direct emission.
Ditch-light legislation and the like aside, I think the characteristics of headlights being visible to 'the public' are far less important than the characteristics of headlights that provide illumination and patterns to locomotive crews. Some of the recent work directly applicable to locomotive headlights involves the use of multiple diodes and reflector segments to give a more coherent beam at high power while maintaining good heatsinking to the individual devices (both the sinks and their cooling usually being optically opaque). When this also enhances visibility of the lights themselves, or reduces any tendency to glare, that's a positive thing, but perhaps should not be a hard design requirement if it conflicts with 'Job One' which is lighting the road for the engineer...
This does raise the issue of 'correct' LED lighting design for anticollision. Which I think is so far underrepresented in practical terms. I encourage anyone's thoughts about what should be provided, and how (as an example, I have worked with active 'skins' for animated images to be activated at or near crossings, similar to those developed for bus advertising)
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