Headlights different brightnesses

[orpine]

Travelling in the evening I've noticed that the trains have two headlights, except that one of them (the "outside" one) is much brighter, than the other ("inside").
I've seen this on XC and Chiltern - no classes I'm afraid; can't remember if I saw it on freights or FGW.

I have some theories but I figured I'd ask the experts; why is this?

 

[yorkie]

Signs are generally on the left hand side.

 

[orpine]

Signs are generally on the left hand side.

I get that, but why does the other light need to be dimmer? Sign placement is generally the same on roads but cars have both lights of the same luminosity.

 

[ECML180]

I believe it is to reduce the likelihood of shining too bright a light at an oncoming driver.

 

[455driver]

One is a headlight the other is just a marker light.

There are only a few trains (91s for one) that have 2 headlights on at the same time.
Just for completeness, some trains have 2 marker lights and a headlight on.

 

[edwin_m]

On some classes one headlight is for daylight use and the other for night time use. The daytime one is on the non-driver side and I guess it would be brighter and focused straigth ahead to give the maximum warning to track workers. I imagine the night time one is angled off to the left to pick up reflective signs as mentioned.

Only one is illuminated at a time, with a marker light on the opposite side, but drivers can use the other one if the preferred one has failed.

 

[TB93]

On some classes one headlight is for daylight use and the other for night time use. The daytime one is on the non-driver side and I guess it would be brighter and focused straigth ahead to give the maximum warning to track workers. I imagine the night time one is angled off to the left to pick up reflective signs as mentioned.

Only one is illuminated at a time, with a marker light on the opposite side, but drivers can use the other one if the preferred one has failed.

+1 on this theory.

 

[scotraildriver]

Where fitted, RH is day headlight, LH is night. The other side is a marker light. In depots 2 marker lights are shown, no headlight. Some trains like our West Highland 156 can show 2 headlights just because it is incredibly dark up there! The "wrong" headlight may be used in the event of lamp failure.

Sorry just noticed another post the same. Move along..........nothing new here

 

[Latecomer]

The night time one being positioned on the left (or right as you face the train) provides sufficient light to pick out signs and other trackside features whilst avoiding dazzling oncoming drivers. It avoids the scenario that car drivers face having to switch between full beam and dipped headlights.

It's noticeable on those occasions that you for example enter a terminus platform at night and there is a train set for departure from a platform immediately to the left. In certain situations the night headlight position can be quite dazzling. Occasionally a driver who is aware will briefly select just marker lights so as not to dazzle the oncoming driver until they have passed the leading cab.

 

[Geeves]

Im unsure of the date, but most stock since at least the 170 DMU and class 66 also have a light mounted centrally above the cab along with marker lights and Headlights.

Blackpool Illuminations on rails!

 

[83G/84D]

The night time one being positioned on the left (or right as you face the train) provides sufficient light to pick out signs and other trackside features whilst avoiding dazzling oncoming drivers. It avoids the scenario that car drivers face having to switch between full beam and dipped headlights.

It's noticeable on those occasions that you for example enter a terminus platform at night and there is a train set for departure from a platform immediately to the left. In certain situations the night headlight position can be quite dazzling. Occasionally a driver who is aware will briefly select just marker lights so as not to dazzle the oncoming driver until they have passed the leading cab.

Drivers are also known to switch to just marker lights after dark when approaching a token exchange point to reduce the effects of dazzling the signalman (or woman).

 

[455driver]

Drivers are also known to switch to just marker lights after dark when approaching a token exchange point to reduce the effects of dazzling the signalman (or woman).

Depends who the signaller is!

 

[Beveridges]

Doesn't stop this happening on the roads. The amount of times I've driven my car at night and quickly got dazzled repeatedly by passing cars headlights.

 

[BestWestern]

Just to add a couple of extra bits and bobs - most multiple units and the most recent loco classes (60, 66, 67, 70) will follow a standard procedure of marker lights both sides and the appropriate day or night headlamp on the respective side. In many cases the markers are multifunction LED type, with a single position capable of displaying both white forward markers and red tail lights. Many units which are fitted with standard spec light clusters (Pacer, Sprinter, 318, 319, 32X etc etc) have had the original units with headlamp/tail lamp/marker arrangement replaced with the new variant which contains only the headlight and combined LED tail/marker position.

 

[A-driver]

Im unsure of the date, but most stock since at least the 170 DMU and class 66 also have a light mounted centrally above the cab along with marker lights and Headlights.



Blackpool Illuminations on rails!

Those 'cyclops' lights are more for show than anything. To make the train more visible to those on or near the line. Pretty sure they go on and off with the marker lights normally but they arnt a headlight and are fairly meaningless to a driver.

 

[DownSouth]

Are ditchlights used in Britain when approaching crossings and stations?

 

[Latecomer]

Those 'cyclops' lights are more for show than anything. To make the train more visible to those on or near the line. Pretty sure they go on and off with the marker lights normally but they arnt a headlight and are fairly meaningless to a driver.

Depends on the traction I think. Certainly on class 378's the 'cyclops' are pretty bright as are the markers, although I've noticed them a lot smaller and dimmer on quite a lot of other traction.

As a further note, if anyone has been curious some people may have noticed an additional light fitted on 378's housed just above the right hand tail light. Most will never have seen this illuminated as it only switches on when the front egress ladder is deployed in order to illuminate the steps.

 

[edwin_m]

Are ditchlights used in Britain when approaching crossings and stations?

No.

The cyclops light is a Euro-standard I think, saying that trains have to be identified by a triangle of lights. I'm not sure how important this is, as you're unlikely to find a truck approaching on the track.

However it's more relevant to trams, and I noticed last night the new ones in Croydon show at least five white lights forward - two headlights, a cyclops light and the first lights on each side is also visible from directly in front.

 

[badassunicorn]

379's also have a white lamp in the bumper(?) for the track debris camera and another light/camera to monitor the pan. Also, as its not been mentioned yet, flashing headlights on/off or the use of hazard lights where both sides headlights flash means a train is in distress.

 

[jon0844]

No.

The cyclops light is a Euro-standard I think, saying that trains have to be identified by a triangle of lights. I'm not sure how important this is, as you're unlikely to find a truck approaching on the track.

Depends if a lorry driver is using some ropey satnav!