Tunnel inspection vehicle stationed at Teebus

A special vehicle created to do inspections in the tunnel had a diesel engine, completely sealed electrics and had a cab at each end so it could be easily driven forward or back. A bicycle was attached in case the vehicle had a problem and the driver could ride back through the tunnel. According to former DWS employee Stephen Mullineux, who supplied the image, it was designed specifically for the tunnel and was based on a tractor chassis. No one knows what has become of it.