There is something about British headlights that I do not understand and was until now unable to find an answer to, so I'll post this question here: Why are British train headlights asymmetrical? I've noticed that this is only on fairly modern rolling stock. Older rolling stock mostly just has marker lights and no real headlights. And why is the headlight arrangement mirrored in the night? Is this used to differentiate a train from other forms of transport (e.g. cars)? Why doesn't Britain use the three-light arrangement used in the rest of Europe? Thanks for your answers in advance.
The driver side light is for night running and the other side is for day running, if I recall correctly
Yes that is correct, but my question is WHY is it like that? What's the reasoning behind this? I don't know any other country in the world that uses such a system and I can't see any use of having separate day and night headlight patterns. Also only using one headlight at a time doesn't seem to be very useful. Sure train headlights aren't very useful for seeing up ahead in any case but reducing this amount isn't helpful either
Day head is on the secondman's side, night head is under the driver. The small marker lights should also be lit. Day head is to notify those on the track that a train is approaching. Night head is also to notify of a train approaching, and to light up trackside warning boards / speeds. Having one inactive serves as a back up, and one is effective enough on its own to light up reflective surfaces such as signage, on modern units you will usually find a ‘cyclops’ light that is also lit.
The night light is a bit brighter than the day one (although not very useful if you want to see in front of you at night). Some newer designs have just one light, which can be dimmed or brightened instead of having separate night, day, marker an (in some cases) tail lights.
It is also worth noting that a train headlight isn't there to enable the driver to see what's ahead, just for anyone else to see the train coming.
Yes for sure, but if they wouldn't need them to illuminated something they could only use marker lights. In the rest of Europe for example, trains have pretty powerful headlights. They help to illuminate signs and not self-illuminated signals at night and are used to check the track when riding on sight (e.g. due to a signaling failure).
good thing the class 700 doesnt have these, like, having them being different on the left and right side of the vehicle
The 700s are horrible to head towards and I find they dazzle me slightly during both the day and night. Horrible lights, way too bright for their own good.
Day headlights for daytime. Night headlights for nighttime. If the lights are white, then the train is moving forwards. Red light indicates the train is moving away from you. The night headlights are brighter so the train can be more visible and so that lineside signage is more visible.
yeah thanks but i guess everyone here already knows the basics of train headlights but the question was WHY are they ASYMMETRICAL?!
One side is small, the other big. With the day time setting, the brighter light is on the inside so as to not to dazzle passengers at stations or workers on the track. The night light needs to be brighter (and therefore bigger) on the other side for signage to be seen clearer. Sorry, was meant to put that in my original post.
This is the case most of the time except on newer stock with symmetrical light designs, but the Class 442s (at least in their days with South Western Railway) also broke this scheme, with the day headlight on the driver's side, rather than the night light. This is because of the design of the train's front fascia, having the headlights behind the same glass as the windscreen. As a result, glare became a major issue with the LED headlights fitted to the units as part of their failed refurbishment. This photo from 47soton.co.uk shows this in action. There is no difference in physical size between the housing for night and day headlights.
You wrote: "The night light needs to be brighter (and therefore bigger) on the other side for signage to be seen clearer." When you write 'top light' I assume you mean the top headlight, above the cab windows, in which case your correction is also wrong, as these headlights are smaller than or the same size as the main headlights. If you mean the day and night headlights compared to the marker lights, this is circumstantial as while some trains (like Electrostars) have the headlights positioned slightly above the marker lights, other trains have them on the same level or above.
I'm more basing it off the 395s. (I maybe should have mentioned that to make my explanation clearer) On these units, there are two lights on either side of the cab (one big, one small). The bigger light is the day/night setting, while the smaller light is a backup. The top light is brighter on the left side (for night) and the right side (for day). Obviously the configuration is different depending on the train (of which I already know as I work with 3/4 different ones), but the light is always bigger on either side depending on if it is set to day or night.
Should add that the standards changed in the early 2010s for full Symmetrical lighting on new designs. Originally many BR trains had little to no lighting, Southern EMU's the only headlamp was the light to illuminate the route blinds! Later many were refitted with a single Headlamp and later still the Day/Night light came in with the modular clusters BR Introduced. High Level lights came in just before Privatisation with the 92s being the first Locomotives to get the high level lights
