Citation

Gonseth AT. Highw. Res. Board bull. 1960; 255: 79-91.

Copyright

(Copyright © 1960, National Research Council (U.S.A.), Highway Research Board)

DOI

unavailable

PMID

unavailable

Abstract

The Port of New York Authority has previously conducted experiments in conjunction with the installation of mercury-vapor transitional lights in the Holland Tunnel. The experiments were run during periods of maximum annoyance due to sun glare, which exists for about one hour per day at most, when the sun is between 5 degrees north to 5 degrees south of due east. The tunnel approach ramp is in a due east direction. Sun position data show that the sun is above the horizon in that position only during the period of March 21 to September 21. Allowing for rainy and cloudy days during that period, it is estimated that this occurs only about 120 days per year. The study reported in this paper was conducted to determine if the flow of traffic is affected during the winter months when the tunnel entrance ramp is shaded by local industrial buildings. If not, possibly a decorative facade constructed over the portal could shade the entrance in summer as well as in winter and thereby reduce, if not eliminate, the need for extensive transitional lighting all year long. Once the vehicle operator passes under a tunnel portal the decided reduction in light intensity causes a speed reduction until his eyes have adjusted to the change. Transitional lighting, of course, has improved this operational feature considerably. New facilities are being equipped with flared portals and variable transitional light sources controlled by photoelectric cells. However, on existing tunnels and underpasses it would be almost impossible in many cases to flare the portals, and costly indeed to revise the facility lighting system to adapt an automatically controlled variable light source. With this in mind it was thought that it might prove easier and more economical to reduce the light intensity outside rather than increase it inside the tunnel.