What is the carbon footprint of stopping a car and starting it again?

Question

I've noticed a rash of people using crosswalks as though they are entitled to stop every car on the road so they can cross the street without missing step. They could, like people use to do, just wait for a clearing in the traffic and cross the street, but instead now I see people crossing the street without even looking at traffic, 'knowing' that everyone will stop for them...under penalty of the law.

I'm trying to do a little write-up on the ecological benfits of x-walk courtesy, but I'm having a hard time finding the statistics to prove my point: stopping and re-starting cars is a BIG waste of energy.

Thanks -Jeff

Answer 1

The cross walk courtesy rule is, pay to have pedestrians use a different level than do cars.

Pedestrians crossing under or over the streets, so that they do not inconvenience motorists become a necessity when pedestrian traffic is very heavy.

The same principle applies to autos crossing each other's path on different levels. We have cars standing still half of their time in many cities, congested beyond capacity.

We can improve the situation by using systems of one-way streets, and well synchronised lights. But we are just trying to use a different dimension, like time or a horizontal separation to avoid the use of the vertical dimension.

Some cities it is almost impossible to make turns, left or right, because of continuous pedestrian traffic. Move those people up a couple floors and they cross, both ways, without interfereoing.

Answer 2

I can't find an exact number on the carbon impact of one stop and start.  It will be a function of the size of the vehicle and the rate at which you accelerate back up to speed.  I did find that quick acceleration back up to speed creates a carbon footprint 60% higher than it would be for the one time acceleration at a lower rate of acceleration.  teh lesson?  Do decelerate or accelerate too fast if you ahve the choice.

Mutual courtesy between pedestrians and vehicle drivers wold be excelent.  I encourage you to empahsize that with your article.  Thanks for your efforts.

Answer 3

Cars don't have feet.