[sustran] Fuel consumed by idling

[Todd Alexander Litman]

Please cite sources for the claim that 40% of fuel is used from 
idling. I suspect that it is a misinterpretation of the data. A 
typical vehicle consumes about a tenth as much fuel per unit of time 
while idling as under load (typically about 1 liter per hour for a 
car and 2 liters an hour for a large truck). If an average vehicle is 
driven 1 hour per day and idles 5 minutes, idling represents about 1% 
of total fuel consumption.

I think Cassini may be confusing idling with stop-and-go driving 
conditions, but I'm skeptical that the traffic management strategies 
he advocates would actually increase traffic efficiencies. I think 
there is a good case for converting stop signs and signal 
intersections to roundabouts, but I've yet to see evidence that 
eliminating traffic controls altogether ("naked streets") reduces 
delay or crash risk overall in most situations.

There are many anti-idling campaigns underway, but most seem to 
exaggerate the benefits, they are an excuse to avoid the more 
critical reforms needed to reduce economically excessive vehicle 
travel and associated social costs (see http://www.vtpi.org/wwclimate.pdf ).


Best wishes,
-Todd Litman


At 10:42 AM 5/6/2007, Martin Cassini wrote:
>Dashing out, but in the UK, about 30% of our CO2 output is from traffic.
>Prof David Begg admits that 40% of that is from traffic idling. How
>often does traffic idle at lights for no good reason? I live in King's
>Cross, and I would say a good (or bad!) half the time. Also you have to
>add the cost of manufacturing, installing, maintaining and RUNNING the
>galaxy of 24-hour lights - this alone represents a massive carbon
>footprint. If it wasn't for the lights, traffic would filter and flow,
>instead of continually stop, idle and re-start. Traffic volume can be a
>drama, but volume + controls = crisis.
>
>Martin


Sincerely,
Todd Alexander Litman
Victoria Transport Policy Institute (www.vtpi.org)
litman at vtpi.org
Phone & Fax 250-360-1560
1250 Rudlin Street, Victoria, BC, V8V 3R7, CANADA
"Efficiency - Equity - Clarity"

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