Abstract
Maintenance factors in installation of tunnel lighting have been considerd in terms of traffic volume and tunnel length based on results from investigations into the use of tunnels. Ventilation conditions in tunnels are drastically improved by reinforcing exhaust gas regulations for cars, and dirt on luminaire is also remarkably reduced. Further, the life times of light sources are advancing. Therefore, we studied lumen maintenance factor, survival factor and partial maintenance factor by using dirty luminaire to take maintenance factor into consideration and these suggested a new method of establishing maintenance factor.
