The Forum

As I mentioned in my previous post about Wilson Drive, there are many reasons not to use stop signs to calm traffic. One reason I did not discuss in much detail is the increase in automobile emissions resulting from the placement of a stop sign.

This was the only government site I could find which quantified the emissions increases resulting from the placement of just one stop sign. These statistics should give us pause as we consider placing unnecessary stop signs. If anyone has access to EPA or other government statistics, please send them to me.

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Why Don't They Put Up More Stop Signs?

Delaware County, OH Website

One of the stronger arguments against multi-way stop intersections is air pollution. Research indicates the following results per 1000 automobiles decelerating to a stop and then accelerating again:

From 25 MPH
Carbon Monoxide (CO) 13 lbs.
Hydrocarbon (HC) 1.0 lbs.
Nitrogen Oxide (NOx) 1.1 lbs.
Fuel Consumption 5.6 Gals.

From 35 MPH
Carbon Monoxide (CO) 24 lbs.
Hydrocarbon (HC) 1.7 lbs.
Nitrogen Oxide (NOx) 1.9 lbs.
Fuel Consumption 8.7 Gals.

When queues build up in an approach, and cars have to move up in the queue one car length at a time, emissions and fuel consumption increase with the queue length. One car joining a 10-vehicle long queue will emit and consume 10 times as much of the above listed quantities than it would if arriving directly at the STOP sign.
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