Comparative Analysis of Passenger Traffic Fleets in Asian Cities: Technology, Driving Activities, and Emission

Abstract:

The road transport sector is the major emission source of toxic air pollutants and greenhouse gases (GHGs) in large Asian cities. This paper comparatively analyzed on-road passenger traffic fleets (cars, buses, taxis, motorcycles), using local data collected in cities of Bangkok (BKK), Kathmandu, Hanoi, Ho Chi Minh City (HCMC), and Yangon. Surveys were done in 2010-2014 to obtain information on vehicle technology, driving activities (speed, distance, number, and types of starts), traffic density, and fuel characteristics.

Large shares of pre-Euro vehicles were still observed, especially for public buses. The most advanced technology was Euro4, which was observed in small shares (<5%) of the personal car fleets in BKK, HCMC, and Yangon. Euro3 was generally the most advanced technology found in other fleets in these cities. Motorcycles (MC) was the most dominant fleet in all cities, except in Yangon, where they were not allowed. Low vehicle speeds, mainly below 25 km/h, were observed for all vehicle types, indicating traffic jams. Natural gas and LPG had considerable shares in BKK and Yangon while for other cities diesel and gasoline were still the two major fuels used in transportation. Running emission factors (EF) of buses and taxis in Kathmandu were considerably higher than other cities due to its hilly topography, low speeds, high mileage, and less advanced vehicle technologies. The number of passenger vehicles per 1000 people were 400-500 in HCMC and Hanoi (mainly by MC) and in BKK (also by cars), moderate in Kathmandu (200) and the lowest in Yangon (40) because of the MC ban.

Annual emissions of the passenger fleets were calculated for each city using the International Vehicle Emission (IVE) for 14 species. BC and OC emissions were estimated using their fractions of PM₁₀ emission. Annual emission per capita of toxic air pollutants and GHGs was analyzed. For example, the emission in kg/year/person for CO, VOC, NOx and PM₁₀ in these cities was 24-150 for CO, 0.9-23 for VOC, 2.1-8.2 for NOx and 0.2-1.1 for PM₁₀. The highest per capita emissions of CO and VOC were found for HCMC and the lowest for Yangon, which showed the influence of MC fleet. The per capita emission of Kathmandu was ranked second among the cities. Our results were also analyzed in comparison with the per capita emission estimated for other Asian cities.