Headlights

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blue sabre

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I'm sure the answer is simple, but why do trains have one headlight on one side and just a marker light on the other? How come it isn't a standard 2 like cars?
 
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slick

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Something I've always wondered aswell! The rules have obviously changed down the years because the 315, 317s I drive when on the mainline display both marker lights and a headlight whereas the 379s and modified 315s and pretty much every modern EMU/DMUive seen now display one roof mounted marker light, one headlight in day or night mode and one marker light opposite which ever headlight is illuminated. Just to throw in a spanner, most modern tube stock have two headlights and no marker lights? I'd be interested to know also!:|:-?
 

BestWestern

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I've always believed it had something to do with dazzle and glare, hence the use of a different configuration at night, though that could be rubbish!

The brightness of modern traction headlamps, particularly those on multiple units with their own in-built lighting arrangements rather than the group standard 'bolt-on' clusters, can be pretty immense head-on and a pair of them coming at you would be blinding.
 

ainsworth74

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It's worth bearing in mind that train headlights are less to illuminate the line ahead and more to act as a marker so that people can see the train coming.
 

BestWestern

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It's worth bearing in mind that train headlights are less to illuminate the line ahead and more to act as a marker so that people can see the train coming.
Very true, though the powerful lighting fitted today seems to do a very good job of both. I recall a Class 150 cab ride in the dark with the orignal lighting clusters and visibility was practically nil! :o
 

David

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IIRC the configuration of headlights is during the day, the right hand light is lit, with the others merely being markers mainly to be visible to track wrokers, etc.

During the night it's the left hand light that fully lit in order to highlight the cess to pick out things like speed restriction boards etc. At least that's my understanding from readin posts on here and elsewhere about headlights.

Would a driver like to confirm or correct that please?
 

Geeves

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Just add another small thing. Class 142s since built (and most still do) only have one headlight. I think its the day setting? Northern have been modifying the fleet recently for both day and night headlights.
 

driver9000

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Just add another small thing. Class 142s since built (and most still do) only have one headlight. I think its the day setting? Northern have been modifying the fleet recently for both day and night headlights.
As built they had the left 'night' light only. Most Northern 142s now have a 'day' light now.
 

swt_passenger

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In that document, i couldn't instantly see an exemption for LU vehicles.
That's a bit of a minefield in my experience. I think there must be some sort of 'memorandum of understanding' for LU vehicles on NR metals, and as discussed before, the 'yellow panel' isn't used by them either. I know LU don't normally allow track workers or patrolling during operating hours, so their own rules (ie for pure LU infrastructure) have less visibility requirements, as there should never be anyone on or about their lines.

Never found anything written down about LU on NR yet, although I've looked for it in the past. (Drifting off topic a bit, it's a bit like the often mentioned 'rule' that all stock operating on LU must have a tripcock. That doesn't apply to SWT units on the District line south of East Putney for some reason.)
 

Old Timer

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I'm sure the answer is simple, but why do trains have one headlight on one side and just a marker light on the other? How come it isn't a standard 2 like cars?
The answer like many of this kind is to be found back in the 1970s.

With the continuing introduction of MAS the BRB decided that there was no further need for trains to display a reporting number, although this was quite controversial with us on the ground who firmly believed the opposite, for a number of reasons.

At night the reporting box indicators had provided a poor but visible source of frontal lighting to an otherwise black train, and this did at least give you some warning. On a good night, in the right conditions, you could see a reporting number from up to a mile away. Street lighting and other light pollution however meant that this was reduced significantly in urban areas.

This resulted in the decision subsequently to modify the boxes to contain light units, normally consisting of two lamps for redundancy. The reason for this was to make the train more visible at night to staff on the line.

With the introduction of the Class 87s from 1973 the standard was for two marker lights which were to be lit during the day and a centrally positioned high intensity lamp which was to be used at night.

Initially the light was located around buffer level as this was the closest to eye level however experience quickly revealed that visibility was improved with the lamp placed at a higher level and thus with the Class 56s in 1976 the lamp was placed towards the bottom of the cab windows.

By now the Standard required two marker lights together with a high intensity bulb for night time use on all new build stock. Existing lococs with a reduced life expectancy were permitted to operate with two frontal lights only, other locomotives were modified during main works to be equipped with the new headlamp arrangements.

From the early 1990s the high intensity lamps were altered so that they focussed towards the left hand side with the beam providing illumination up to about 100 yds ahead of the traction unit.

The reason for this was two-fold, firstly to assist the driver when examining the line, and secondly to assist in illuminating the new standard retro-reflective lineside warning signs.

The current frontal light standard reflects the UIC requirements.
 
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