and the second is to enable the Driver to see the line ahead in situations where he is required to carry out an examination of the line. Hence the way that the beams are focussed.
A further benefit is that it allows track-side signage to be retro-reflective, hence saving the costs of lighting certain signs that previously would have been lit.
Prior to the introduction of headlights it was extremely difficult to carry out an examination of the line, and needed the Driver to be accompanied.
Thanks for making those points OT. I remember well from my Toton days numerous occasions where, on a pair of Class 20's, being required to examine the line at 2, 3 or 4 o'clock on a Winters morn, sometimes up some dark deserted colliery branch, with only a pair of marker lights, equivalent to a couple of candles, lighting my way!
The introduction of headlights has improved things no end, making it much easier for examination purposes, but also for locating the little landmarks that all Drivers use as reference points for navigation, braking points, etc. Sometimes these landmarks can be very insignificant, especially at night. A bridge number, the back of a lineside sign applying to the opposite direction. Approaching Radford Jct from Trowell the braking point for the 35mph restriction over Radford is nothing more than a little pole sticking up from the cess. Were it not for headlights then many of these would be invisible thus causing increased journey times.
As regards the brightness of the modern BMAC headlights, i can only say that they have made a tremendous improvement to nightime visibility on EMT's Sprinter fleet. The older style were often so bad as to be really not worth bothering with. Yes they can dazzle, but if you apply the same technique as outlined in the highway code for when you are dazzled by a cars headlights, ie avert your gaze to the left, then it ceases to be that much of a problem (unless i've got a splitting headache!)