Double Blunder: UK Cities Propose Blanket 20 MPH Limit; ABGreen Calls It A Fuel Saver

by Paul Niedermeyer

Published: December 16th, 2009

double blunder uk cities propose blanket 20 mph limit abgreen calls it a fuel saver

It’s getting late in the game today and we’re down a couple of points, so its time to go for a double. Thanks to an easy pitch from the UK government and AutoBlogGreen, I’m going to swing. The Nanny State Incarnate is encouraging local UK governments to introduce blanket 20 mph speed limits in all residential area. And ABG picks up the story from Autocar and adds its own little brilliant addition to the story: its going to save fuel. Now how is it that a writer for the biggest little green blog in the land doesn’t know that cars are way less efficient at 20 mph than at their peak efficient speed of somewhere between 35 and 50? And there’s more; in fact this might well be a triple:

It’s not that 20 mph limits didn’t already exist in some cities, but they had to include calming devices like speed humps and chicanes. This proposal by the UK government would free cities to impose the limits city-wide, as was done in a recent trial in Portsmouth. Road safety minister Paul Clark explains:

We have seen that 20mph zones with traffic calming measures can make a real difference to the safety of local roads,” he said. “But we’ve also looked at the latest research and listened to councils and residents who want to introduce 20mph limits on a series of roads where physical traffic calming measures aren’t possible or practical.

“Allowing councils to put in place 20mph speed limits on more streets without speed humps or chicanes will mean that they can introduce them at a lower cost and with less inconvenience to local residents.”

AutoBlogGreen adds its insightful editorial perspective: “Besides saving a few gallons of fuel, these limits are being touted as a safety measure that can also encourage cycling and walking.”

Ok, I’ve passed second, and I’m going for third:

The government is also proposing that average speed cameras be used in residential areas to enforce the limits.

There it is! ABG, it’s not about saving fuel, but about making more money for the government coffers. Silly you.

Did I make it to third safe, or was that stretching it?

#20MileLimit #20Mph #FuelSaving #SlowerIsNotMoreEfficient #SpeedLimits #UKSpeedNannies

Paul Niedermeyer

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5 of 19 comments

Martin Schwoerer on Dec 17, 2009

I don't buy you guys' criticism.

Economy: your point is not proven, Paul. Or is it? Travelling at a smooth 20 is surely no less economical than at 40. The UK has thousands of roundabouts / traffic circles and when you're travelling at 20, there's less braking and accelerating to be done. (Obviously, the situation is different when you have a Hybrid). Hardly anybody is so dumb as to drive around in first gear at 20, just about everbody recognizes after a while that third is best.

Travel speed: as Tom Vanderbilt has noted (and his book has been reviewed *twice* by TTAC, and both reviews were very positive) urban traffic flows like rice, not like water. Driving fast increases congestion, just like when you try to force rice through a funnel. Studies have shown that overall urban travel speeds do not suffer much when speed limits are decreased.

Safety: go to around 20 (with modern, pedestrian-friendly cars), and you potentially *eliminate* pedestrian deaths. That's nothing to throw your shoes at.

TTAC likes to kvetch about the UK. TTAC also likes to forget that the UK traffic regime has been exceedingly successful in reducing traffic deaths in the past decade. Too lazy right now to search for the source, but if I remember correctly, the US would have around 10k fewer deaths per year if it matched the UK's safety standards.

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- Geeber on Dec 17, 2009
  
  The U.S. fatality rate (deaths per 100 million miles driven) is at a record low figure, and even the raw number of fatalities dropped dramatically this year. We've been very successful in reducing traffic fatalities, too. I would wager that our higher rates have more to do with lower rates of safety belt use (the local paper lists whether those killed in accidents were wearing safety belts; about 90 percent were not) and deaths in more remote areas, where drunk driving is more common and accident responders must travel a greater distance to reach the victim. As for studies showing that urban travel speeds do not decrease much when speed limits are decreased - that only proves that most people pay as little attention to speed limits in urban areas as they do on limited access highways. Traffic simply flows at its own rate.
  
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- Paul Niedermeyer on Dec 17, 2009
  
  ABGreen added the line on "saving gas" without any explanation or reference. I took it as a knee-jerk assumption that a reduction of speed always results in fuel savings. That simply is not true.
  
  If there is evidence to show that a blanket reduction in speed limit to 20 somehow saves fuel, I'd be happy to see it and reconsider my position.
  
  My general comment on the reduction of the speed limit is that it seems quite heavy handed to have it apply city-wide, without consideration of the variance in street design and natural traffic speed. 20 may be just right in a very congested area, but it may be insufferably slow in others.
  
  Obviously, my reaction may be colored by the fact that our US cities are built very differently than in Europe. But here in Eugene, the city has gone mad with putting in speed bumps everywhere, which also clearly increase fuel consumption and increase noise levels and wear and tear.
  
  Regarding reduction in traffic fatalities in the UK; good for them. I don't know whether pedestrian fatalities are included in these numbers or not. But other than pedestrian fatalities, its hard to imagine reducing the limit from 30 or 25 down to 20 can have a meaningful impact on fatalities of passengers. It's a bit hard to get killed at those speeds inside a modern car.
  
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Martin schwoerer on Dec 17, 2009

Reduction in fatalities 1979 - 2002: US: -16.2% UK: -46.0% Source: Wikipedia "automobile safety"

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- Paul Niedermeyer on Dec 17, 2009
  
  Again, without having the facts, this may not be a useful or directly relevant piece of information. I do know that European fatalities were generally much higher in Europe in the sixties and seventies, due to conditions (fewer freeways) and the poor safety of small cars back then. The Europeans had much more opportunity for improvements than in the US.
  
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