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Old June 1st 07, 01:23 AM posted to uk.transport.london
Mr Thant Mr Thant is offline
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First recorded activity at LondonBanter: Mar 2007
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Default Petition - M3 single lane restriction at the M25 Junction 12 and M3 New Road Layout Project

On Jun 1, 12:00 am, "Rob (UK)" wrote:
To quote Jeremy Clarkson he said that "If you reduce the number of
lanes from 2 to 1 then you have to double the speed to get the same
number of cars throug per hour"


Except it's wrong. You have to halve the headway (in time terms),
which only requires doubling the speed if the headway (in terms of
distance) stays the same. If you can halve the distance between cars
then no increase in speed is necessary. Given that stopping distances
at lower speeds are disproportionately shorter, reducing the speed
actually increases throughput.

U