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With severe crashes remaining steady, Boulder’s transportation department keeps focus on the core arterial network

Though overall vehicle crashes are trending down, severe crashes, which largely occur on main roadways in Boulder, have remained consistent, according to the Safe Streets Report presented in Tuesday’s Boulder City Council special meeting.

The report, released every three years, shows an overview of traffic crash trends in the city between 2018 and 2020.

It found that while the total number of crashes per year in Boulder has trended downward since 2016, severe crashes have remained consistent. Severe crashes are defined as those resulting in serious injury or fatality.

Crashes involving bicyclists, left turns and speeding were the most common categories of severe crashes between 2018 and 2020, according to the report.

The 28th and Colorado intersection in Boulder is one of the sites for planned safety upgrades, including building a protected intersection, new lanes and a multiuse path.(Cliff Grassmick/Staff Photographer)

Since 2016, there have been anywhere from 55 to 60 severe crashes a year — aside from 2020, when there were 38 — due to shutdowns, virtual school, people working from home and other coronavirus pandemic-related factors that kept people off the road.

Boulder’s City Council heard some about the city’s Vision Zero efforts and the Safe Streets Report in December, when a full report remained impending, but dug in a bit more Tuesday now that all the data has been released.

The findings further reinforce the direction provided by the City Council in its annual retreat: Focus on the Core Arterial Network, dubbed the CAN, largely because the vast majority of severe crashes occur on these busier roadways.

The idea, unanimously supported by the City Council in January, was proposed by Mayor Pro Tem Rachel Friend and Councilmember Matt Benjamin. Complete with a catchy phrase and acronym — Yes we CAN (core arterial network) — they proposed bike, pedestrian and safety improvements meant to get people out of their cars.

The two-phase plan would focus, among other things, on adding protected bike lanes and dedicated bus lanes in core arterial networks, or the busier roadways where 65% of city crashes occur.

Local streets account for 11% of severe crashes, yet represent 54% of the city’s street network.

Councilmember Nicole Speer asked if staff had any insight into why this happens, other than narrower streets in neighborhoods contributing slower speeds.

“I would say that the arterial roads certainly are our busier roads that do have higher speeds, and of course also have just a higher number of lanes, right? So there’s a lot more opportunity for conflict and interaction between modes at those locations,” Principal Traffic Engineer Devin Joslin said.

Data from the Safe Streets report indicates that 94% of severe left turn crashes occurred on an arterial roadway, as well as 77% of severe pedestrian crashes and 52% of severe bicycle crashes.

“Everything keeps directing us toward making our core arterial network safer,” Major Aaron Brockett said.

The “20 Is Plenty” effort, an effort to reduce speeds to 20 mph on many residential roads that was unanimously supported by the Council in 2020, has thus far proven relatively ineffective in reducing speeds.

This is a separate initiative from Vision Zero, which looks to eliminate traffic-related fatalities and serious injuries, though the goals of both are closely related.

Boulder’s challenge to reduce speeds in a statistically significant way is in line with other cities, such as Portland and Seattle, which also implemented lower speed limits, city transportation staff noted.

However, the “20 Is plenty” evaluation did find that street design, including narrower streets without a centerline, had a demonstrable impact on lowering speeds, and its findings generally align with the Safe Streets report in that the data showed severe crashes happened on main roads, not local streets.

A number of projects to address some of the issues outlined in the Safe Streets report are underway, including construction of a protected intersection at 30th Street and Colorado Avenue, design of a protected intersection at 28th Street and Colorado Avenue and design of multiuse path enhancements on East Arapahoe Ave.

The key focus areas for projects include pedestrian and bicycle facility enhancements and traffic signal system upgrades, according to information presented in Tuesday’s special meeting.

Moving forward, the city plans to finalize the Safe Streets report and the “20 Is Plenty” evaluation. It then intends to begin updating the Vision Zero Action Plan and to initiate of the Core Arterial Network projects that the City Council expressed support for in the annual retreat.

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