title: Fuel use and emissions comparisons for alternative routes, time of day, road grade, and vehicles based on in-use measurements.
abstract: The objective here is to quantify the variability in emissions of selected light duty gasoline vehicles by routes, time of day, road grade, and vehicle with a focus on the impact of routes and road grade. Field experiments using a portable emission measurement system were conducted under real-world driving cycles. The study area included two origin/destination pairs, each with three alternative routes. Total emissions varied from trip to trip and from route to route due to variations in average speed and travel time. On an average trip basis, the total NO emissions differed by 24% when comparing alternative routes and by 19% when comparing congested travel time with less congested traffic time. Positive road grades were associated with an approximately 20% increase in localized emissions rates, while negative road grades were associated with a similar relative decrease. The average vehicle-specific power based NO modal emission rates differed by more than 2 orders of magnitude when comparing different vehicles. The results demonstrate that alternative routing can significantly impact trip emissions. Furthermore, road grade should be taken into account for localized emissions estimation. Vehicle-specific models are needed to capture episodic effects of emissions for near-road short-term human exposure assessment.
authors.affiliation: Department of Civil, Construction and Environmental Engineering, North Carolina State University, Campus Box 7908, Raleigh, North Carolina 27695-7908, USA. frey@ncsu.edu
authors.forename: H Christopher
authors.initials: HC
authors.lastname: Frey
authors.forename: Kaishan
authors.initials: K
authors.lastname: Zhang
authors.forename: Nagui M
authors.initials: NM
authors.lastname: Rouphail
mesh_terms: D005742:Gasoline; D018986:Motor Vehicles
chemical_list: D005742:Gasoline