CO CONCENTRATION INSIDE THE CROSS HARBOR TUNNEL IN HONG-KONG

Carbon monoxide (CO) concentration within the Cross Harbor Tunnel in H ong Kong was investigated. Non- air-conditioned double deck buses trav elling through the tunnel were used in the study to monitor the CO con centration and the distribution of CO in the tunnel. The Cross Harbor Tunnel was designed and built with a semi-transverse ventilation syste m during the middle of the 1960s. The quantity of fresh air was calcul ated according to the dilution required to keep CO from vehicular emis sions within an acceptable level. The ventilation system of the tunnel was found effective in diluting this pollutant from vehicular emissio ns. Most CO concentrations measured in the tunnel were lower than the CO standard concentration value (30 mu L/L) in the Hong Kong Air Quali ty Objectives, and much lower than the original design standard. The i mpacts of traffic volume, vehicle speed, ventilation, piston effect, a nd other elements on the CO concentration in the tunnel were analyzed. A simple model for CO concentration estimation was derived and examin ed. It can be used to predict the CO pollution in the Cross Harbor Tun nel.