Driving legally in Boulder will officially mean slowing down a little bit from the previous default speed limit of 25 miles per hour on many residential roads.
City Council on Tuesday unanimously made final a change, celebrated by local advocates who popularized the phrase “20 is plenty” in the area through their campaign for a 20 mph speed limit on roads classified as local. Streets known as collectors, like 55th and 26th streets, with 25 mph posted speed limits will not be changed.
For $65,000 in city funding, coming out of a pool of $700,000 allocated by Council to city transportation staff’s Vision Zero crash reduction project, 465 street signs will be replaced with the updated speed limit by mid-summer, officials said, and Boulder’s welcome signs at city limits will also be updated with the new default speed limit. Most streets the new rule impacts do not have signed speed limits, so the lower default speed limit will be the top legal velocity on them.
The action was taken in hopes it will boost the safety of walking, biking and driving in Boulder, with officials citing evidence of there being greater chance of survival for victims of a crash involving a vehicle traveling 20 mph versus 25 and 30.
“Results show that the average risk of severe injury for a pedestrian struck by a vehicle reaches 10% at an impact speed of 16 mph, 25% at 23 mph, 50% at 31 mph, 75% at 39 mph, and 90% at 46 mph,” a 2011 AAA Foundation for Traffic Safety study referenced by Councilman Aaron Brockett stated. “The average risk of death for a pedestrian reaches 10% at an impact speed of 23 mph, 25% at 32 mph, 50% at 42 mph, 75% at 50 mph, and 90% at 58 mph.”
Risks vary significantly by age, the research found, with the average chance of severe injury or death for a 70‐year‐old pedestrian struck by a vehicle traveling at 25 mph similar to the risk for a 30‐year‐old pedestrian hit at 35 mph.
There may be some benefits other than safety to slowing down, Boulder resident Chelsea Stencel humorously pointed out on Twitter.
“I was just slowly driving through my neighborhood on my way home and if I was going faster I might have never seen the VERY attractive man who smiled and nodded at me so yes I believe this defeats all arguments against the push for 20 mph speed limits in Boulder,” she tweeted with the hashtag #20isplenty. (She later told a reporter she does not endorse getting distracted by good-looking people, or anything else, while behind the wheel, saying, “I do not encourage gawking and driving.”)
While city staffers have noted that changing the behavior of motorists will take more than the slower speed limit, including infrastructural changes to make roads less conducive to speeding, Brockett also shared a 2018 post from the Insurance Institute for Highway Safety on research showing that lowering the speed limit from 30 to 25 in Boston made a difference with slower driving.
Not everyone was in support of Council moving as quickly as it did on this matter. City staff earlier this year recommended to the Boulder Transportation Advisory Board and Council to pursue piloting lower residential speed limits in only certain areas and studying the effects and engaging the community on the issue, before converting to the slower cap citywide.
That route would have been more expensive, additional funds needed for the pilot before making the change permanent. Staff before the Tuesday meeting recommended Council make the change across all of Boulder, after the elected officials and board members unanimously supported that direction.
“I’m writing to express my alarm regarding the decision to reduce maximum residential speeds from 25 to 20 mph. What is the problem you are trying to solve and is reducing speeds the best solution? What is the data that calls for a 20% reduction in speed limits across the whole city? A change of this magnitude deserves a citywide discussion before implementation,” Dorothy Riddle wrote in an email to Council.
The new speed limit ordinance takes effect June 18.
“Enforcement related to the Neighborhood Speed Management Program will include the use of warning letters and violations through the Boulder Police Department’s Photo Radar Enforcement program,” city staff stated in a memo to Council. “For streets with a 20 mph default speed limit where a photo radar van is deployed, motorists will receive a warning letter for travelling 25 to 29 mph. In compliance with the state enabling legislation, motorists traveling 30 mph or faster will receive a violation which includes a financial penalty.”