There is a third train running parallel to the train that is ahead of the camera train, throughout the entire trip. It almost looks like it has an array of fluo

There is a third train running parallel to the train that is ahead of the camera train, throughout the entire trip. It almost looks like it has an array of fluorescent tubes or mercury vapor lamps. Sometimes the train with the lighting rig gets a little bit ahead of its subject, which is why the train being filmed gets dark from time to time, but you can see this rig clearly at the beginning, and towards the end, the camera train pulls close enough that you can see the staff on the lighting rig train walking about its platform.