Blue strobe lights on trains, what are they all about?

As far as I know the only blue light used as a signal on trains means that workmen are on, under or near equipment and it must not be coupled to or moved.

They can be either on steady or flashing.

Arcing from the pantograph might be a possible cause, or perhaps a high intensity white light that appears somewhat blue from a short distance?

Well if you're certain it's not arcing from the pan there isn't anything else it could be. Trains do not have flashing blue lights on top or anywhere else.

However, the phenomenon that you've described is as perfect a description of arcing at the pantograph as I have read. When it's cold and there is a lot of moisture in the air the water condenses out onto the cold contact wire. As an electric train comes along these water droplets or, if it's cold enough, ice crystals cause a continuous arc where the pantograph is in contact with the wire. This is very bright and appears to flicker or strobe as the pantograph is drawn along. The light from the arc is reflected back from the train roof and it does appear that the pantograph is being lit from below, but I can assure you that it is not.

Yes, it is probably arcing from the pantograph and catenary wire. This happens on a cold frosty night, especially if a train has not traversed the line for a few hours, I used to experience this in Wellington, New Zealand in the early hours when I was driving commuter trains.

The strobe lights you are seeing are actually electricity arcing from the contact bar and the overhead wire. There is no need for strobes to be fitted on top of trains.

Keep you eye on the road though.

As J G said...

It sounds like you're seeing sparks from the pantograph (the frame that connects trains to overhead cables) !

Are you sure that's not the sparks from the overhead power lines?