Also discussed here: Impact of Modern Roundabouts on Vehicular Emissions (10 page pdf, Srinivas Mandavilli, Eugene R. Russell, Margaret J. Rys, Proceedings of the 2003 Mid-Continent Transportation Research Symposium, Ames, Iowa, August 2003)
Today we review two studies that examine the impact of modern roundabouts on reducing vehicle emissions compared to an intersection with traffic lights. Results indicate reduced Carbon Dioxide, Carbon Monoxide and Nitrogen Oxide emissions of about 26% with up to 50-60% reductions at peak traffic flow times.
Key Quotes:
“When vehicles are idle in a queue they emit about 7 times as much carbon monoxide (CO) as vehicles traveling at 10 mph. The emissions from a stopped vehicle are about 4.5 times greater than a vehicle moving at 5 MPH” “In another study ..in Sweden, .. replacing a signalized intersection with a roundabout resulted in an average decrease in CO emissions by 29 percent and NOx emissions by 21 percent and fuel consumption by 28 percent per car within the influence of the junction”
“there are significant reductions from the roundabout for all parameters, ranging from a 16.36% reduction in nitrous oxide to a 26.05% reduction in hydrocarbons compared to the traffic signal“
“At its peak hour, the roundabout reduces carbon monoxide at the intersection by 8.5 kg/h. Peak hour …is generally regarded to represent about 1/10th of the daily volume. That makes the daily reduction of CO approximately 85 kg/day”
“a signal which meets design criteria will produce up to 26.05% more emissions than a roundabout at the same location“
“The average Carbon Dioxide (CO2) emissions (Kg/hr) for the intersection locations studied are 16 percent and 59 percent less for the AM period and PM periods respectively for the case of a modern roundabout”
“The average Oxides of Nitrogen (Nox) emissions (Kg/hr) for the intersection locations studied are 20 percent and 48 percent less for the AM period and PM periods respectively for the case of a modern roundabout”
Related articles
- U.S. cracks down on vehicle emissions (news.cnet.com)
- Air quality measures in B.C.'s Lower Mainland can't keep up with urban sprawl: report (vancouversun.com)
- Roundabouts and Traffic Lights (lunatractor.com)
- Kanata South roundabout approved at committee (cbc.ca)
- Province unveils Pooles Corner plans (cbc.ca)
- Cautionary Road Rules - Gary Lauder Explains How Roundabouts Can Result in Less Crashes (TrendHunter.com) (trendhunter.com)
- Lake Stevens plans two traffic circles to ease Frontier Village congestion (heraldnet.com)
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