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Humping bad for the planet

Road humps slow the traffic but speed up death of planet - Times Online
They damage cars and give drivers a nasty jolt, but now speed bumps have been found guilty of an even worse crime — they are helping to destroy the planet.

The traffic-calming measures double the carbon dioxide emissions and fuel consumption by forcing drivers to brake and accelerate repeatedly, according to a study commissioned by the AA. A car that achieves 58.15 miles per gallon travelling at a steady 30mph will deliver only 30.85mpg when going over humps.

The results, calculated by averaging the performances of the two cars, also showed that reducing the speed limit from 30mph to 20mph resulted in 10 per cent higher emissions. This is because car engines are designed to be most efficient at speeds above 30mph.

A motorist who observed the speed limit on one mile of 20mph road during a daily journey would produce an extra tonne of CO2 in a year compared with driving at 30mph on the same stretch.

That whistling sound you can hear is the your local transport expert weirdy-beardy at the council's brain exploding as he tries to understand this.

Comments

"A motorist who observed the speed limit on one mile of 20mph road during a daily journey would produce an extra tonne of CO2 in a year compared with driving at 30mph on the same stretch."

Let's do some simple arithmatic. First, let's take the 58.15 mpg car and consider what percentage of all cars on the road today reach this level of efficiency. Mmmm... no real data available. So, for the sake of discussion, lets say that the avarage mileage of the average car is 40MPG. So if our 40MPG car travels one mile it uses 1/40 of a gallon of gasoline. And if it drives this one mile every day, in one year it will have used 9.125 gallons of gasoline (1/40=.025x365=9.125. Now a gallon of gasoline weighs maybe 7 1/2 pounds and it's made up of carbon (oh no!) and hydrogen and other goodies. So even if we say that the entire 7 1/2 pounds is carbon and is combining with another 15 pounds of oxygen to create CO2 (very rough numbers I know) we have 22 1/2 pounds of pollutants. Where does the "tonne of CO2" come from? This doesn't even consider the fact that they are talking about the difference between driving 30MPH and 20MPH.

I think we can suspend further discussion of this particular piece of reporting.

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