By Dom Nozzi
July 12, 2016
In recent weeks, I have been alarmed and saddened by the uptick in vehicle crashes in the Boulder area that have led to serious injuries and deaths. I was touched and encouraged last night by the strong showing of support for a big improvement in traffic safety for Boulder at my Boulder Transportation Advisory Board meeting (of which I am a member).
I have been a bicycle commuter since I was a young boy. I have spent the past 35 years both academically and professionally in the field of transportation – particularly in the area of transportation safety for bicyclists, pedestrians, and motorists.
That background has made traffic safety one of my most important objectives of advocacy, and a primary reason why I was interested in serving on Boulder’s Transportation Advisory Board.
I think it is very important that our Board respond to the heightened community concerns about the state of traffic safety in Boulder with support for an agenda we as a Board recommend to City Council.
Indicators of Traffic Safety
If we are to make any meaningful progress in reducing the number of serious crashes in Boulder, we must be able to measure trends to know whether our safety measures are succeeding. In my view, there are three primary measures:
(1) Annual Number of Serious Crashes. This measure is readily available and has not shown any substantial downward trend for a long time.
(2) Average Speed of Motor Vehicles. This measure is difficult to quantify, but given long-term trends in conventional street design, average speeds are likely to have plateaued at a high level or has increased over time. We know that average motor vehicle speeds are strongly correlated to the number of severe crashes.
(3) Level of Motorist Inattentiveness. At least one study I have seen reports that approximately 80 percent of all motor vehicle crashes are due to inattentiveness. Unfortunately, it is nearly impossible to measure the level of inattentiveness. Nevertheless, it is extremely likely that motorist inattentiveness has skyrocketed in recent decades due, again, to long-term trends in conventional street design, as well as an American lifestyle that has grown increasingly busy and exhausting.
Street engineering and Safety in Numbers are head and shoulders above other common safety efforts, in terms of effectiveness. Indeed, Boulder’s laudable goal of achieving Vision Zero will not be meaningfully approached without street engineering reform.
As has been said many times, good street design produces desirable and safe travel behavior.
By far, the most effective way to increase road safety is to engineer Boulder streets to reduce average car speeds and increase motorist attentiveness. Traffic engineers are well-versed in how to do this.
In particular, minimizing the curb to curb distance on streets and intersections is essential.
The Same Old Song and Dance
For the past century, the status quo for Boulder and the State of Colorado has been to employ warnings, and the “forgiving street” paradigm for road safety.
Conventional warning methods (the “Five Warnings”) long used in Boulder (and other cities) include Warning Paint, Warning Lights, Warning Signs, Warning Education, and Warning Law Enforcement. These warnings are almost entirely ineffective when roads and intersections are oversized, and after a century of employing these warnings, they now suffer from severely diminished returns.
Street design is “forgiving” when street design “forgives” the motorist for driving too fast or too inattentively. This design paradigm strives to minimize the likelihood of motor vehicle crashes by seeking to minimize the consequences of driving too fast or too inattentively. Forgiving design has converted a large number of Boulder streets into high-speed highways rather than the local and slower streets they should be. The following are design examples:
- Travel lanes that are extremely wide;
- Roads that contain a large number of travel lanes or turn lanes;
- A large vision triangle at intersections;
- A large clear zone on the sides of roads (removing trees or other stationary objects);
- Super-elevating road curves;
- Intersections with a large turning radius.
The following links describe this strategy.
http://www.pps.org/blog/what-can-we-learn-from-the-dutch-self-explaining-roads/
https://www.cnu.org/publicsquare/new-science-street-design
http://nacto.org/docs/usdg/design_safe_urban_roadsides_dumbaugh.pdf
Today, following several decades of forgiving street design, average car speeds are higher and motorist inattentiveness is a far worse public safety problem. In many ways, forgiving street design is the reason for these higher speeds and increased inattentiveness.
Fortunately, Boulder is beginning to move toward a new street design paradigm. But relatively narrow, attentive streets such as those found in Boulder’s Holiday neighborhood are the rare exception rather than the rule.
Nearly all of the recent, significant car crashes in Boulder have occurred on major roads. Our dilemma is that a large number of Boulder residents seem unwilling to humanize such roads to make them safer (reducing dimensions to reduce car speeds, for example). And there remains a strong desire to maintain relatively high speed, free-flowing traffic on such roads, which is in direct conflict with safety objectives. One commonly heard strategy for those who oppose the safety redesign of major roads is to recommend that bicyclists avoid such roads. But this is naïve, in conflict with healthy city objectives, and discriminatory.
It is also naïve to think that Boulder can ever comprehensively provide such things as protected bike lanes, off-street paths, and safe pedestrian crossings for the enormous number of destinations that bicyclists and pedestrians need to access. While protected lanes and safe pedestrian crossings have a role to play, it is incumbent on us as a city to recognize that over-sized, high-speed highways are inappropriate in cities and must be reformed to be compatible with safety objectives and healthy city objectives. Many other cities have done this. There is no reason that Boulder cannot follow that path.
Cities thrive when streets induce slower, more attentive travel speeds, and when streets safely allow travel by pedestrians and bicyclists. In part, such design advances city health by promoting “agglomeration economies,” where people and businesses are induced to be compactly drawn to each other (or co-located near each other).
Ruinously, nearly all Americans have aggressively worked for several decades to ensure that communities enable higher car speeds.
Cities are degraded and unsafe when large, high-speed highways intrude into them. Such design has a repelling influence on people and businesses that induce them to disperse and separate from each other. Social capital and a sense of community thereby decline as well.
Toward a New Vision for Traffic Safety
For Boulder to make meaningful progress in reducing serious motor vehicle crashes, new methods must be employed in the future.
It has become increasingly clear after decades of use that the “Five Warnings” are not working well.
Nor are the forgiving street tactics.
Instead, there is a growing recognition of the need for street design that obligates slower motor vehicle speeds and more attentive driving. This design is by far the most effective way to increase road safety in Boulder. Traffic engineers are well-versed in how to do this.
Given the above, I have proposed that the Boulder Transportation Advisory Board support the following. Admittedly, they are largely long-term tactics, but after 100 years of using counterproductive approaches, it should not surprise us that there are few if any quick fixes.
- The City should ramp up its program to redesign streets. Lane repurposing should remain in the city toolbox for roads that contain a large number of travel lanes. Major roads should be Complete Streets. Local and collector neighborhood streets – which today are excessively wide and unsafe on a large percentage of streets — should be incrementally redesigned to be slow streets, shared streets, and give-way streets.
On-street parking should be employed much more often (and retained where it already exists), and existing one-way streets should be converted back to two-way operation (one-way streets are exceptionally dangerous and inconvenient for bicyclists – not to mention their toxicity to retail and residences). Lane widths and turning radii at intersections need to be incrementally reduced as well.
- The City should restore funding or find new funding to finance a ramped up street redesign program to create low-design-speed streets.
- The City should ratchet down the use of the “Five Warnings”: warning signage, warning lights, warning paint, warning education, and warning law enforcement. These tools have been over-used to the point of being a distracting, counterproductive tactic that reduces safety.
- To take advantage of the powerful safety benefits of Safety in Numbers, the City should redouble efforts to significantly grow the number of bicyclists and pedestrians and transit users. Tactics can include pricing, Eco-Pass provision, compact development, and parking reform, for example.
- The City should incrementally strive to increase street connectivity. By having more connected streets, bicyclists and pedestrians can better avoid using more dangerous major streets.
- The City should put a moratorium on the creation of new double-left turn lane intersections, and incrementally convert double-left turns to single-left turns (removal of left- and right-turn lanes is particularly important in the Boulder town center). City data shows that major intersections are the location of an enormous number of crashes. Double-left turn lanes create huge intersection sizes and high-speed, inattentive driving. Such intersections are far too scary/dangerous for all but the most skilled, courageous bicyclist, and the crossing distance for pedestrians makes these intersections very undesirable – particularly for seniors, the disabled, and children. Double-left turn intersections are in direct conflict with safety objectives and efforts to leverage Safety in Numbers.
- The City should strive to minimize the size of service vehicles and buses so that larger vehicles do not become an excessively large design vehicle. When emergency, service and delivery vehicles are relatively large, the excessive size becomes the “design vehicle” that road engineers use, which ends up driving the dimensions of city streets. Huge vehicles should not be determining the size of our street infrastructure. Street sizing in a town center should instead be based on safety for pedestrians and bicyclists, human scale, and overall quality of life.
The time for Boulder to start using effective tactics for improved traffic safety is way overdue.
Dom's Plan B Blog 