Our newest edition of Dangerous by Design has “design” in its name, but what do we mean when we say that street design is a large factor responsible for this epidemic of deaths?
Roadway design has a strong impact on how people drive and is often more influential on driver behavior than the posted speed limit. While speed limit signs may only be posted every few blocks or miles, the road’s design is ever-present, continually providing guidance and visual cues. While there are myriad factors involved in these deaths, our streets are designed to move many cars quickly at the expense of safety for everyone who uses them.
Let’s look at some real-world examples from one of the country’s most dangerous metro areas to show how our streets are dangerous by design, and why no one should be surprised that people routinely get killed while using them.
Typical arterial roadway design leads to the deaths of people walking
Union Avenue (pictured above, looking east and west respectively) is a main road located in the heart of Memphis, TN, the third most dangerous metro area in this year’s report. Union Avenue is worth examining closely, because its design is typical of the most dangerous roads for people on foot within metro areas, classified as an “arterial highway.”
Though termed a “highway,” it’s not limited-access, and it also serves as a city street running through a complex environment with lots of people present. That’s one reason why these roads are the most deadly type: 60 percent of all 2020 deaths occurred on non-interstate arterial highways like this one. According to NACTO, if you look only at urbanized areas, that number grows to between 64 and 67 percent, even though this type of road only makes up 15 percent of all roads.
How speed is prioritized on Union Ave. at the expense of safety
(1) Design can be more influential on behavior than speed limits
When roads are wide and straight, lanes are wide and plentiful, and intersections are infrequent or non-signalized, people feel safe and comfortable driving faster—even when the speed limit is low. Though the limit here ranges from 25-35 mph, this road is designed for far higher speeds. And while the limit changes, the design stays the same.
(2) Other streets regularly intersect Union, but lack crosswalks or signals
This is because keeping vehicles from stopping (speed) is prioritized ahead of providing frequent crossings (safety).
(3) Numerous destinations means that more people will be present
There are grocery stores, a college, a high school, a hospital, shops and stores, and hundreds of homes and higher density apartment buildings. There are also numerous curb cuts and driveways, resulting in dozens of intersections for people walking.
(4) Marked, signalized crosswalks are located as much as 0.4 miles apart
This potentially requires a 10-minute round trip to reach a destination that’s directly across the street. Multiple bus stops are also located in between these distant signalized crosswalks.
(5) Sidewalks exist, but as an afterthought
They are narrow with numerous curb cuts for turns and frequent obstructions, and no buffer between people walking and vehicles moving at high speeds.
These types of design decisions send two contradictory messages to drivers:
- Expect to see and yield to people outside of vehicles, and
- Expect to travel fast all the time.
This puts drivers in a terrible position, and when they fail and strike someone walking or crossing the street, we rush to blame the driver (or probably more likely the person walking) in spite of the fact that the transportation agency should be held responsible for their design choices.
How did this become so commonplace?
Back in the 50s, we started building a system of separated highways to move vehicles quickly over long distances, removing intersections and other points of conflict, development, and pedestrians. Precisely because they knew that speed was not compatible with the complexity of cities and towns. But then somewhere along the way, we started applying this same high-speed highway design within complex urban environments, while keeping all of the conflicts and complexity in place.
Higher speeds make conflict harder to spot and avoid and crashes more deadly. The higher the speed, the narrower the driver’s field of vision, making it harder to see and anticipate potential problems by responding and slowing down or stopping the vehicle. And the higher the speed, any crashes that do occur are far more likely to lead to serious injury or death.
The results are streets designed for speed and the unmitigated carnage that follows.
Note: while this oft-used graphic below is still a good analysis of the relative impact of speed, the age and source of the data means it also almost certainly understates the likelihood of death:
Most fatalities on Union Avenue (and most arterials) occur at intersections
Let’s examine a specific intersection along this same stretch of Union Avenue and a few specific ways that design choices—some of which are completely conventional and acceptable practices, we should note—lead to danger for people on foot.
(1) All four gently rounded corners allow right turns at high speeds, precisely when pedestrians have the right-of-way
Sharper turns require drivers to slow down and turn more slowly. In fact, a recent study shows that a 30-foot turning radius vs. a 10- foot radius will probably result in 30 percent more pedestrian crashes.(See inset at bottom right.)
(2) Sweeping corners exist for speed rather than safety
They increase the distance required to cross on foot, putting people in harm’s way for more time, or making it impossible to cross in time for the young, old, or disabled.
(3) Existing crosswalks are faded or invisible
When signalized intersections are far apart, as they are on Union, it’s even more vital that they be highly visible.
(4) Sidewalks also have obstructions (utility poles, boxes, etc.) and lack rubberized or high-visibility markings to help all people safely cross
For people in wheelchairs or pushing strollers, sidewalks with obstructions can force them into the street to pass.
How do we end up with dangerous streets like these? How can we make them safer?
One of the things we’re most excited about with this year’s edition of Dangerous by Design is the handful of guest supplements from other organizations. Chuck Marohn from Strong Towns—an engineer with years of experience—explains how the engineering profession is part of the problem. He suggests that engineers like to believe that they “don’t control the speed at which people drive.” Yet:
When building a high-speed roadway, the engineer will design wider lanes, more sweeping curves, wider recovery areas and broader clear zones than they will on lower-speed roadways. There is a clear design objective (high speed) and a professional understanding of how to achieve it safely. There is rarely any acknowledgement of the opposite, however: that slow traffic speeds can be obtained by narrowing lanes, creating tighter curves, and reducing or eliminating clear zones. High speeds are a design issue, but low speeds are an enforcement issue.
Chuck and Strong Towns closes that piece with some great practical suggestions about how local residents and policymakers can make our streets safer. But what types of specific changes can be made to produce slower speeds and safer streets? In the second of four guest supplements, Alex Engel and Kate Fillin-Yeh from the National Association of City Transportation Officials (NACTO) explain how proven tools—from safer speed limit setting to safer street designs—are proven to save lives, and can quickly stem America’s traffic safety crisis. Don’t miss it.
VIDEO: We prioritize speed above safety on the most dangerous roads
We hope this post makes it clear: prioritizing both safety and keeping cars moving quickly—outside of limited access roads like interstate and freeways—is impossible. As the most dangerous type of road, if we mobilized a true safety effort on these arterial roads, we’d make an enormous reduction in fatalities.
For even more on design, don’t miss this rich, visual explanation we produced on how street design impacts the speed of vehicles and why we have to choose between speed or safety: