This article describes the arrangements for lighting in all parts of the Channel Tunnel and various aspects of its construction. From the beginning of construction, it was necessary to have very reliable and efficient lighting, adapted to a very intense undersea construction operation. The construction lighting installations followed close behind the massive tunnel-boring machines as they advanced. This `temporary' lighting had to remain in use for several years, to provide site and safety lighting, not only for boring, but also for tracklaying, catenary erection, and extensive cabling and piping installations. It had to be effective across the whole tunnel width, with 12-15 lux average at floor level, mounted from the concrete lining midway along one side. The British and French construction lighting installations differed, mainly because of different tunnelling techniques imposed by geological differences between the two ends of the tunnel. The permanent lighting was developed to meet very different requirements, with a common solution throughout the tunnel, comprising both `Main Lighting' and `Safety Marker Lighting'. Safety and ergonomic conditions indicate that the rail tunnels should be nearly dark, but the emergency evacuation walkways along their sides need lighting.
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