Study of the Emissions Generated at Intersections for a SI Car under Real World Urban Driving Conditions

A precision in-vehicle tail-pipe emission measurement system was installed in a EURO1 emissions compliant SI car and used to investigate the variability in tail-pipe emission generation at an urban traffic junction. Exhaust gas and skin temperatures were also measured along the exhaust pipe of the instrumented vehicle, so the thermal characteristics and the efficiency of the catalyst monitored could be included in the analysis. Different turning movements (driving patterns) at the priority T-junction were investigated such as straight, left and right turns with and without stops. The test car was hot stable running conditions before each test, thereby negating cold start effects.

To demonstrate the influence of the junction on tail-pipe emissions and fuel consumption, distance based factors were determined that compared the intersection drive-through measurements with steady speed (state) runs. Fuel consumption was increased at intersections by a factor of 1.3∼5.9. CO, THC and NOx emission were increased by a factor of 8∼26, 6∼21 and 2.5∼10 respectively. Benzene emissions were also increased by a factor of 4∼21. Through fine-scale analysis of real-world driving profiles and tail-pipe emissions, this research makes a contribution to our understanding of the variability in driving parameters and emission production in urban areas. The results of this study will be useful in advising the development of combined traffic/ emission models for urban areas and developing optimal traffic management strategies to minimise emissions.