On the Relations between Driving Patterns, Exhaust Emissions and Network Characteristics in Urban Driving

Sammanfattning: The planning and design of street networks in cities influence driving behaviour and give rise to variations in driving patterns (i.e., speed and acceleration profiles) that affect exhaust emissions and fuel consumption. The primary objective of this study has been to use real-life driving patterns to investigate how the characteristics of street networks influence fuel consumption and vehicular emissions. The effects of imposing limits on driving patterns and of aggregating them in single speed profiles were also explored. The analyses and results are based on four different driving pattern studies that yielded both experimental and ob-servational data. The use of samples of extended driving patterns and of regression analysis made it possible to estimate the magnitude of the impact of different characteristics of street networks. It was found that there were considerable discrepancies between exhaust estimates based on a single mean speed profile aggregated from a sample of driving patterns and estimates based on the full sample of driving patterns. Consequently aggregated profiles must be treated cautiously when estimating emissions. It was also found that specific types of streets, calming measures or intersections can both add to and reduce exhaust emissions. Speed reducing measures showed effects leading to the conclusion that they on an overall total have a reducing effect on exhaust emissions. There is often a discrepancy between the overall influence and the expected local effects. Behavioural adaptation between successive driving environments was also found, supporting the conclusion that driving is not only influenced by the current environment but also by the preceding. Investigations of the overall environmental effects of driving patterns should take into account not only local effects but also the influence of the adjoining environment.