They damage cars and give drivers
a nasty
jolt, but now speed bumps have now 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. A car that achieves 29 miles
per gallon travelling at a steady 30
mph will deliver only 15 mpg
when going
over humps or through stop signs.
In the UK, an independent engineer
was engaged
by the AA and he used a fuel flow meter
to test the consumption of a small
and a medium-sized
car at Millbrook Proving Ground in
Bedfordshire.
The results, calculated by
averaging the performances of the two cars, also showed that reducing the
speed limit from 30 mph
to 20 mph
resulted in 10 per cent higher emissions.
This is because car engines are designed
to be most efficient at speeds
above 30
mph.
A motorist who observed the
speed
limit on one mile of 20 mph road during a
daily journey would produce an extra ton
of CO2 in
a year compared with driving at 30 mph
on the same stretch.
In an unusual move for a motoring
organisation,
the AA called for the introduction of
cameras that detect average
speeds to
replace humps.
Edmund King, the AA’s president,
said:
“Humps are a crude, uncomfortable and noisy
way of slowing people down
and this
research has shown they are also environmentally
damaging. We accept that traffic speed
needs to be controlled
in residential
areas where there is a problem with
accidents and children are playing. We think
motorists are more likely to
accept average
speed cameras than humps.”
Previous research by the Transport
Research
Laboratory found that air pollution rose
significantly on roads with humps.
Carbon monoxide
emissions increased by 82 per cent
and nitrogen oxide by 37 per cent.
The London Ambulance Service
has claimed
that the 30,000 humps on the capital's
roads cause up to 500 deaths a
year because
its crews suffer delays in reaching
victims of cardiac arrest.
Humps tend to breed more humps
and stop
signs more of the same. If one street has
humps and more stop signs
installed,
the next street calls for humps and
signs and eventually you find no clear
roads for movement of emergency
service vehicles.
Transport for London has been
helping
to test average-speed cameras on residential
roads. No tickets are being issued
yet,
but the mere
presence of the cameras has resulted
in the proportion of drivers complying
with the limit increasing by a third.
The new cameras are not linked
but have
synchronised clocks and each separately
transmits information to a processing
centre.
This allows
several cameras to work together without
the need to dig up the road between them
to lay cables. In urban areas this
can halve
the cost of installing the system.
Putting in 50 standard humps
on three
or four connecting residential streets
costs about $300,000. A set of eight
average-speed
cameras covering
the same area would cost $500,000.