This paper describes an assessment of pollution emission rates determined for a typical urban traffic stream of New Zealand vehicles. The technique used for this assessment was that of a `tunnel study' in which concentrations of air pollutant within an inner city road traffic tunnel are measured while simultaneously monitoring air flows through the tunnel, vehicle numbers, vehicle speed and behaviour. This technique has advantages over more conventional techniques such as dynamometer testing or infrared beam tests in that it includes the effects of hot and cold running, driver behaviour, and a large sample of vehicles (approximately 40,000), and provides data on their combined effect. This study was combined effect. This study was undertaken in two tunnels in the Wellington inner city, the Mt Victoria Tunnel and the Terrace Tunnel. Differences in mean speeds in these tunnels enabled rates to be determined for several mean speeds of vehicle stream, namely 35 km/h (approximately), 50 km/h and 85 km/h. The findings of the study are that, for New Zealand vehicles, emissions of carbon monoxide are about 10-20 percent higher, and nitrogen oxides 90 to 100 percent higher than was found for vehicles in a similar study undertaken in the Van Nuys Tunnel, Los Angeles. (A)
Abstract