A big lens aperture would give a limited depth of field, so something would have been out of focus. The shot is pretty well sharp from front to back, which indicates a smallish aperture.
There are also some people on the platform in the far distance. They are not blurred, which indicates a shutter speed of 1/30th of a second, or faster.
I reckon a flash was used. The giveaway is the illuminated area of sloping platform in the foreground close to where the photo was taken. The light then fades to darkness for a short distance, until the platform lights starts to brighten the area under the canopy.
If it’s not a flash, another remote possibility is another illumination source from behind the camera such as another loco or station/trackside lamp.