20 is Plenty on Neighborhood Streets (Letter to Council – Sept 17th meeting)


Dear City Council,

Community Cycles commends the Transportation Advisory Board and city transportation staff for doing such a great job on the 2019 Transportation Master Plan update. The 2019 TMP is thorough, innovative and puts an emphasis on public safety. Staff did a fantastic job on public outreach and this TAB is more engaged, productively proactive, and well informed than any we have ever worked with. Big kudos all around. 

As you know, we have asked TAB, Council and staff to consider our request to start a public process to lower speed limits to 20 mph on residential streets in Boulder.  Our recent op-ed in the Daily Camera laid out our case for this request. 

We write to share additional background and information in hopes it might be helpful.

Lowering speeds to 20 mph on residential streets is not a cure-all.  A new paper called Vehicle Speeds and Traffic Safety by transportation consultant Jim Charlier explains the technical issues around speed management and provides context for speed limit reductions. “Speed-related safety problems are caused in part by street design and cannot be completely rectified by setting lower speed limits. The best chances for success comes through coordinated programs of street safety improvements and lower speed limits,” he writes.

Lowering speed limits should be considered a foundational piece of the Vision Zero effort. We need to start somewhere. A 20 mph speed limit will serve as a building block as the city implements neighborhood traffic mitigation projects, Neighborhood GreenStreets and other supportive strategies. 

The move toward lower speed limits on residential streets is relatively recent so robust data on its effectiveness is only now emerging. The three most comprehensives studies do indicate either modest reductions in speeds or are inconclusive. Keep in mind, a 2 or 3 mile an hour reduction in speed can mean the difference between life and death.

The experience in Portland OR might be helpful as they embraced a 20 mph speed limit in 2017. In an email exchange with a member of our advocacy committee, staffer Matt Kelly of the Portland Bureau of Transportation provided this insight: 

“As I’m sure you know, there can be a great deal of skepticism about the impact of speed limits. Street design is likely the most important factor in travel speeds, but we do not see that as a reason to ignore the potential benefits of speed limit reductions, especially given their relatively low cost and ease of implementation.

In addition, I would argue that the 20 mph reduction has provided benefits that are not necessarily visible on the street. It has generated media attention and public interest that has helped us publicize the impact of speed on safety and to promote our broader Vision Zero goals. It has aided speed limit reductions on larger streets by providing a lower “baseline” by which to compare them to. It supports our work internally with our planners and engineers to discuss the importance of identifying design speeds in all our projects and making sure we build toward those speeds.

I don’t have any specific anecdotes about the impact of the 20 mph speed limit. In general it has been very popular. Typically the only negative comments relate to a desire for traffic calming measures to support the 20 mph speed limit. People have rarely complained about the speed limit itself, they simply tend to want better compliance.”

The traditional practice of setting speed limits based on how fast people drive (called the 85th percentile), which is used in Boulder, has been discredited. Charlier writes, “The concept that speed limits should be set using observed speeds of vehicles in freeflow traffic conditions is based on data from vehicle to vehicle collisions in rural places collected in the 1950s. There is no modern research basis for use of this concept in setting speed limits on city streets where pedestrians and bicyclists are likely to be encountered.” While the 85th percentile is still in national guidance, the Federal Highway Administration is expected to update that guidance in early 2020. This paper by the Institute of Transportation Engineers explains the changing landscape of setting speed limits. 

Breaking the deadly cycle of traffic violence requires bold moves by leaders. Boulder has an opportunity to lead in this space, building on the strong bones of infrastructure already in place in our community. The recent Designing Cities conference in Toronto featured several panels on Vision Zero, including one highlighting the work of city staff in Seattle, Cambridge and Portland to lower speed limits. Most are having to battle state traffic code and other authorities for the right to reduce speeds. Portland had to convince the state legislature to pass a bill to allow them to do so. As a home rule city, Boulder can do it more easily. Our efforts will contribute to the growing momentum for safer streets for all. 

We thank you for your leadership and stand ready to assist. 

Community Cycles

The new Transportation Master Plan (TMP) will go before Council in mid-September. The TMP  provides a vision for a safer, more equitable system of transportation in Boulder. This vision includes a heightened emphasis on safety for all road users — people who walk, bike, drive automobiles, and take transit. 

If enacted, the 2019 TMP will help prevent the crashes that catastrophically impact the lives of the city’s residents. 

This is the most thorough and forward thinking TMP Boulder has ever produced. City transportation staff and the Transportation Advisory Board should be applauded for all the hard work that went into this project. Boulder’s TMP will be an example to many cities and will put Boulder back into a leadership role in transportation planning and innovation. We can’t say it strongly enough: great job!

But a great plan is one thing. Action is another. Boulder should adopt the TMP and move quickly to implement it. The city should accelerate improvements on streets like Lehigh and 30th. The City should also address speeding. We at Community Cycles feel that neighborhood streets are a good place to start. We ask the City to begin the public process to reduce the default speed limit on residential streets to 20 mph (from 25 mph).  “Twenty is plenty” is a worldwide movement with hundreds of cities adopting 20 mph residential speed limits — cities like Boston, Portland, and Seattle.  

Residential streets make up about 70 percent of Boulder’s street network and a large proportion of public space within neighborhoods. Few residential streets have marked crosswalks or bike lanes, requiring people that walk, bike or drive to share the road. Some are narrow with limited visibility. Some are key routes to schools, transit stops and places where people shop, work and recreate. Children play and pets roam on these neighborhood streets. 

Conventional wisdom has said that driver behavior is modified by the street environment, not by posted speed limits. But new research is showing that median speeds do drop slightly when posted speed limits are changed. Even a modest drop of 2 mph would be meaningful on neighborhood streets in terms of safety, comfort and noise. 

More importantly, new research has shown a measurable reduction in the speeds of the drivers who significantly exceed the posted speed limit. This is critical: fatalities begin to increase dramatically above 20 mph. The likelihood of death from impact at 30 mph is double that at 25 mph. Reducing the number of drivers excessively speeding in residential zones will reduce the severity of crashes. 

The idea of slower neighborhood streets is already hugely popular among Boulder residents. The city’s Neighborhood Speed Mitigation Program (NSMP) was created in response to community outcry over speeding, traffic noise and unsafe conditions on streets where people live. The NSMP program requires neighbors to organize and complete a lengthy application to request traffic calming on their street. Even with the heavy lift required to apply, the program is vastly over-subscribed — 58 neighborhoods have applied but only 16 projects will be completed by the end of year two of the program. By adopting a city wide speed limit of 20 mph on all residential streets, the city would bring equity to this program and help achieve more livable streets for every neighborhood.

You can help calm the traffic in front of your house. Community Cycles encourages every parent who worries about the safety of their kids and everyone else who is concerned about the danger of speeding traffic to attend the Transportation Advisory Board meeting on September 9 and the City Council meeting on September 17 or send an email to TAB@bouldercolorado.gov  and Council@bouldercolorado.gov. Ask that they adopt the TMP including a commitment to implementing it and working quickly to adopt a 20 mph speed limit on residential streets. 

There is much talk in Boulder about neighborhood character. When most people think about their neighborhoods they envision a calm, welcoming place, where children play, neighbors walk dogs, and people tend their yards.  

We hope Boulder will agree 20 is plenty for these places we call home.