Researchers have found a speed “sweet spot”. Emissions per mile are fairly consistent when a car is traveling between 35 and 65 miles per hour, but slower speeds tend to reduce fuel efficiency. Interventions that raise the average speed of a trip during rush hour could have a positive effect on efficiency. Programs such as ramp metering, which reduces stop-and-go on highways, and variable speed limits were shown to reduce emissions by 12 percent per … Continue reading Regulating traffic speeds decreases congestion and increases efficiency