I wanted to put a lamp on the front of a train

But i want the lamp to be larger where the light comes from.
at the moment it is a dot!
and it has to be fast processing. this is the blend file

try it as two lights
spot for light projecting from train, as this is the type of light that would be, modify fall off, etc… as needed.
second add a lamp slightly in front of your train light, to create the effect of light from the train lamp shining on the train. again modify so light just covers small area around the train light

Mr. D

the projected light would still look like it is coming from a tiny source.
wouldn’t it?

Hello again
that’s why two lights, the second lamp is there to brighten the area on the front of your train.
also inside your train’s lamp housing map in a ‘shadeless’ material so it appears lit, also your can place a quad infront of the train light with a light halo ring on it, a cheat over a post processing glow effect but can be done in scene(might need z-transparent, but off with tracable and shadowbuf in you materials pipeline settings, don’t want this quad casting a shadow)
Mr. D