Are train head- and tail-lights different at depending on visibility/weather conditions?

[py_megapixel]

This came up in a discussion with a family member about daytime running lights in cars. They asked this question and I wasn't sure what the answer was. The basis for this curiosity is that most modern motor vehicles have two or three sets of white lights on the front, one set (the headlights) for use at night or in other low light conditions where additional light to see by is needed, one set (the daytime running lights) to make the vehicle more visible at all other times, and sometimes an additional set (the fog lights) for conditions where visibility is exceptionally poor. Similarly there are generally two categories of bicycle light - ones 'to see' (equivalent to the headlights) and ones 'to be seen' (equivalent to the running lights).

Do trains have something similar, or are the white lights on the front and the red lights on the rear always the same no matter the prevailing conditions outdoors?

 

[seagull]

Most units/locomotives have fixed "marker" lights, which are always the same intensity day and night - this being roughly the equivalent of automobile daylight running lights. In addition they have a headlight fitting, one on each side, and these generally have a "daytime" and a "nighttime" setting - the night lamp being on the left hand side when sat in the driving seat, the day lamp on the right - so that in the majority of operation, the night lamp is furthest away from a train coming the other way (which would be approaching on the right), so as to reduce dazzling. The intensity of light is, I believe, less for the night lamp too.

Just to confuse matters further, some modern locomotives/units have both sides headlamps lit, day or night, with a simple intensity reduction at night.

And no, in terms of poor visibility/rain/fog, there is no difference at all in lighting used. And no fog lights. Tail lights are always the same, day or night.

Even until fairly recently, front lights on trains were for the train to be seen, rather than for the driver of the train to be able to see anything with them. Doing 80mph with the original Class 158 light setup along a single line in the pitch dark of rural mid-Wales was... well, let's just say you could have worn a blindfold and seen just as much. Basically no illumination at all.

 

[XAM2175]

In addition they have a headlight fitting, one on each side, and these generally have a "daytime" and a "nighttime" setting - the night lamp being on the left hand side when sat in the driving seat, the day lamp on the right - so that in the majority of operation, the night lamp is furthest away from a train coming the other way (which would be approaching on the right), so as to reduce dazzling.

This is the now-superseded British standard.

Just to confuse matters further, some modern locomotives/units have both sides headlamps lit, day or night, with a simple intensity reduction at night.

This is the new European standard.

Quoting from the LOC&PAS TSI:

https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=OJ:JOL_2014_356_R_0004&from=EN

4.2.7.1.1. Head lights
(1) This clause applies to units fitted with a driver's cab.
(2) Two white headlamps shall be provided at the front end of the train in order to give visibility for the train driver.
(3) These head lamps shall be located:
— at the same height above the rail level, with their centres between 1,500 and 2,000 mm above the rail level,
— symmetrically compared to the centre-line of rails, and with a distance between their centres not less than 1 000 mm.
...
(5) Headlamps shall provide 2 luminous intensity levels: ‘dimmed headlamp’ and ‘full-beam headlamp’.
...
(7) Additional head lamps may be provided (e.g. upper head lamps). These additional head lamps shall fulfil the requirement on the colour of head lamps specified above in this clause. Note: additional head lamps are not mandatory; their use at operational level may be subject to restrictions.

4.2.7.1.2 Marker lights
(1) This clause applies to units fitted with a driver's cab.
(2) Three white marker lamps shall be provided at the front end of the train in order to make the train visible.
(3) Two lower marker lamps shall be located:
— at the same height above the rail level, with their centres between 1,500 and 2,000 mm above the rail level,
— symmetrically compared to the centre-line of rails, and with a distance between their centres not less than 1 000 mm.
(4) The third marker lamp shall be located centrally above the two lower lamps, with a vertical separation between their centres equal to or greater than 600 mm.
(5) It is permitted to use the same component for both head lights and marker lights.
...

4.2.7.1.3 Tail lights
(1) Two red tail lamps shall be provided at the rear end of units intended to be operated at the rear end of the train in order to make the train visible.
(2) For units without driver's cab assessed for general operation, the lamps may be portable lamps; in that case, the type of portable lamp to be used shall be in accordance with the Appendix E of the ‘freight wagons’ TSI; ...
(3) The tail lamps shall be located:
— at the same height above the rail level, with their centres between 1,500 and 2,000 mm above the rail level,
— symmetrically compared to the centre-line of rails, and with a distance between their centres not less than 1 000 mm.
...

 

[_toommm_]

Although, unlike cars, the headlights on trains aren’t there to allow the driver to see where they’re going - they rely on route knowledge for that - the headlights are instead so other people can see the train.

 

[edwin_m]

Although, unlike cars, the headlights on trains aren’t there to allow the driver to see where they’re going - they rely on route knowledge for that - the headlights are instead so other people can see the train.

However the headlights allow viewing of signs at night. When trains had only dim headcode or marker lights, only the most critical signs (limits of shunt, temporary speed restrictions and warnings for the most severe permanent speed restrictions) were illuminated, but now lineside signs of all types are retro-reflective like road signs. Route knowledge is still required but the signs are a much more useful reminder now they can actually be seen at all hours!

 

[87 027]

Indeed, non-illumination of a temporary speed restriction sign at night was a factor in the fatal Nuneaton crash of June 1975. The driver was charged with manslaughter but acquitted.

 

[Fincra5]

This came up in a discussion with a family member about daytime running lights in cars. They asked this question and I wasn't sure what the answer was. The basis for this curiosity is that most modern motor vehicles have two or three sets of white lights on the front, one set (the headlights) for use at night or in other low light conditions where additional light to see by is needed, one set (the daytime running lights) to make the vehicle more visible at all other times, and sometimes an additional set (the fog lights) for conditions where visibility is exceptionally poor. Similarly there are generally two categories of bicycle light - ones 'to see' (equivalent to the headlights) and ones 'to be seen' (equivalent to the running lights).

Do trains have something similar, or are the white lights on the front and the red lights on the rear always the same no matter the prevailing conditions outdoors?

I don't know of any trains that have head/marker lights that automatically adjust to the conditions...

700s do have an option for Half/Full Brightness Headlights...

 

[Need2]

Route knowledge is still required but the signs are a much more useful reminder now they can actually be seen at all hours!

You are having a laugh, aren’t you?
You can’t see most of them, even in daylight!
They’re either black with dirt, covered in graffiti or obscured by vegetation.