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Friday, August 01, 2014

Lowering speed limits causes more accidents: a letter to Victoria's Mayor and Council

Dear Mayor and Council:

I recently had the experience of driving on a four lane section of Quadra street that is now marked 40 km/h, as a result I now know where Victoria ends and Saanich begins on that section of road.

I can also report that no one was driving 40 km/h they were driving 50 or even 60 km/h (as a safe driver I was going with the flow of traffic).  A similar thing happens on Blanshard street.  No one drives 50 km/h on the north end of Blanshard they drive at 60 km/h whereas at the south end people drive 40 km/h even though the entire length of the street is posted 50 km/h.  Why because capable drivers don’t drive according to speed limits they drive according to road conditions.

I know I know its that darn pesky counter intuitive thing, “oh lower speed limits must be safer because it's just common sense,” actually it causes more accidents.  Unreasonably low speed limits result in a majority of drivers having to contend with the minority of drivers who ignore road conditions and drive according to what the little white signs tell them to resulting in more accidents,

That is why for example in Britain when certain earnest types lowered speed limits from 30 mph to 20 mph traffic accident rates increased.  This was at the same time that accident rates on the streets they left at 30 mph and 40 mph actually declined.  See the following link:
I know that you all want to do good and lowering speed limits is a great way to get that warm “I made the world a better place” feeling without having to come up with an additional line item on your operating budget.  But the fact is that you didn’t make our streets safer.  You made them more dangerous. 

I don’t always agree with your staff, but in this instance they got it right and you should have listened to them.  They noted the safest speed limits are those posted at the 85 percentile.  They recommended against lowering speed limits and far from saving lives you are actually going to cause more death and injury.

I would therefore request that you carefully track what happens with the accident rates on the streets whose speed limits you recently lowered and that if they increase (as is likely) that you revisit your decision.

To those that voted against lowering the speed limits thank you, to those that championed it please rely more on real world results and less on your “intuitive” thinking.

Sincerely,


Michael Geoghegan

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