An Estimate of Greenhouse Gas Emissions from Light Duty Vehicles Resulting from Traffic Calming Stops in the U.S. Suburbs

Abstract

Both the conversion of internal combustion engine vehicles to electric vehicles (EVs) and the implementation of increasingly strict emission standards are important approaches to limiting greenhouse gas (GHG) emissions in the transportation sector, but further options exist. While stop signs are not permitted for use as a traffic calming measure (speed control) in the United States, their prevalence has increased. This study employs both deterministic and stochastic modeling approaches to quantify GHG emissions caused by light duty vehicle (gasoline and electric power) stops in suburban neighborhoods in the United States at low traffic volumes. Results suggest that traffic calming stops have a substantial impact on GHG emissions from all vehicle classes, including EVs. Furthermore, emissions from the sedan/wagon class and pickup class increased by 102% and 84%, respectively, when speed limit increased from 24 km/h (15 mph) to 72 km/h (45 mph) on roadways with stops. The total GHG emissions at ca. 400 m (ca. 0.25 mile) between stop signs (40 stops) and 48 kph (30 mph) increased from 4.1 kg CO₂-eq (0.25 kg CO₂-eq/km) to 5.6 kg CO₂-eq (0.35 kg CO₂-eq/km, a 38% increase) and 6.4 kg CO₂-eq (0.40 kg CO₂-eq/km) to 8.7 kg CO₂-eq (0.54 kg CO₂-eq/km, a 35% increase) under aggressive driving conditions for the sedan/wagon and pickup vehicle classes, respectively. Similar trends were observed for the other vehicle classes examined in the study. Stochastic modeling predicted that mean emissions from commuting vehicles encountering traffic calming stops in the United States were approximately 1.1 × 10⁶ (range of 2.9 × 10⁵ to 2.1 × 10⁶) metric tons carbon dioxide equivalent (MTCE) per year at a speed limit of 24 kph (15 mph) and 3.1 × 10⁶ (range of 8.1 × 10⁵ to 6.0 × 10⁶) MTCE per year at 48 kph (30 mph).