Mist II - Considerations in setting community wide speed limits

Noise:
The difference in the noise level of a car going 30mph and a car going 40mph is 1000%. In other words, the faster car is ten times louder than the slower car. Research shows that this extra noise adversely affects sleep, play, and learning of people close to busy roadways.

Efficiency:
Due to closer following distances, a roadway can actually move more cars that are traveling 30mph versus 40mph. 30mph is just about the optimal travel speed for maximizing capacity.

Pollution:
Most often, slower travel speeds mean smoother travel, meaning less stop and go traffic. This means less acceleration and braking which is inefficient and causes extra pollution.

Public Space/equity:
A vehicle's speed is a major factor on impacting a community's public space. In general, the faster a vehicle travels the more space it takes up- imagine a 'bubble' of unusable space surrounding a motor vehicle that gets larger as speed increases.

Social Interaction:
One study has shown that 17 mph is the maximum speed at which two people can pass each other and recognize one another.