Why safety and speed are fundamentally incompatible—a visual guide

Designing streets for high speeds dramatically increases the likelihood that a person struck while walking will be killed. Slower speeds are directly connected to improving safety and reducing deaths. So what does it look like to prioritize safety over speed in practice?

Update (June 2022):

We created a new video to take these graphics and do a deeper dive on explaining this concept. Read about that video here, or find the embedded video from youtube below:

Why are the numbers of people struck and killed while walking going up? The biggest reason is that transportation agencies continue to prioritize speed over safety, often in ways that are hard to see. So what does this look like in practice? Let’s take a short visual tour.

Our thanks to Nelson/Nygaard for helping to produce these graphics in Dangerous by Design 2021 . You can also view a slideshow version of this graphic series at smartgrowthamerica.org/safety-or-speed

Speed or safety: choose only one

Speed is the most important factor that determines whether or not a person walking, rolling or getting around with an assistive device survives a collision with the driver of a car. Increase the vehicle speed and the likelihood of survival drops massively.  From our Driving Down Emissions report in 2020:

High speeds also make it more difficult for a driver to safely navigate streets filled with people and complexity. Why?

So, we should decrease pedestrian fatalities by reducing speed. But how?

To do this, most conversations begin with speed limits. But speed limits on their own are less influential than most people think, and we basically allow drivers to set speed limits with their behavior, rather than aiming to shape their behavior with the limits. (Read more about this backwards process here or here.) 

A more holistic approach to safety means using design and engineering principles that prioritize safety instead of speed to give drivers numerous visual cues to slow down and shape their behavior.

So what are some of these design features?

Streets with wide lanes allow room for mistakes and encourage higher speeds, regardless of speed limits.

Almost all of us who have been behind the wheel have been cruising along and then realized we’re traveling well above the speed limit at some point. It happens, and it’s most likely to happen when the design has made it possible; when every visual cue says “go faster, no need to look out for people walking here, no need for stopping, nothing to be mindful of other than other cars.” And so drivers behave accordingly.

On the other side, narrower travel lanes naturally slow traffic by creating a sense of enclosure, regardless of speed limits. Adding streetscaping, trees, or other visual “obstructions” or “hazards” (as a lot of traffic engineers would term them) also help give drivers a cue to slow down.

All intersections are not created equal. Far too many streets lack basic safety essentials like curb ramps & high-visibility crosswalks. Some may have crosswalks on only some of the sides rather than all. Wide, sweeping corners not only result in drivers taking turns at higher speeds (right through crosswalks) but they significantly can increase the distance people have to cross. 

This photo below (submitted to us by Michael Dantzler) is a good example of this concept:

That’s basically only a two-lane road to cross, but with extra wide right turn lanes on either side (more on slip lanes below), it becomes more like crossing six lanes. That puts someone crossing the street in harm’s way for 2-3 times longer than they should be, and all to avoid potential vehicle delay and encourage greater speeds.

The best way to slow speeds is to make crossings clearly marked and visible and prioritize the movement of people through them. Signalized high-visibility crosswalks slow drivers down and make them more aware of people. Extended curbs and narrower turns shorten crossing distances while slowing cars down making a turn.

When the distances between intersections are long, it encourages higher speeds with fewer reasons to slow down. Are you going to drive faster when there’s a stop sign on every block through a neighborhood, or on the arterial road with traffic lights every half mile or more? 

This photo is a good example of a road that sends clear messages to drivers:

  • Don’t slow down
  • Only part of your attention is required
  • Driving here is easy and there are few surprises to worry about.

They’re certainly not going to expect to see a pedestrian crossing the street here, even though in many states any junction with another road is considered a legal intersection, even if unmarked. (Like the unmarked crossing in the above picture near where the person is standing on the left side of the road next to a street junction.)

When intersections and safe crossings are far apart, it leaves people walking with a terrible choice: they can cross “unsafely” in the middle of a block between two destinations (even if legal!), or choose to turn a short trip into a much longer one by finding a safer place to cross. And once again, in many states every one of these street junctions picture above is a legal crosswalk, even if unmarked.

Now would be a good time to mention that state DOTs spend millions on projects intended to shave 2-3 seconds off of an average car commute through a corridor or intersection. But we should expect someone walking to add 20 minutes to their journey?

This is precisely what happened to Raquel Nelson in Atlanta a decade ago.

She got off a bus after a long night with her two children at a bus stop immediately across the street from their apartment in the middle of a long block on Austell Road. Rather than walk an extra 20-plus minutes to the nearest signalized crosswalk with two tired kids, she did what she’d done numerous times and crossed in the middle of the block. Her son was struck by a drunk driver and Nelson was charged with vehicular homicide, though she didn’t even own a car. (Angie Schmitt profiles her story to open chapter three of her terrific book Right of Way.)

It’s unlikely that anyone who heard Nelson’s story and responded with something like “she should have walked 0.6 miles to the nearest crosswalk,” has ever lived a minute in her shoes. She made a logical choice that most people would likely emulate in the same situation. Yet no one seemed to ask, “why is there a bus stop across the street from an apartment complex with no crosswalk?” Or “maybe we should put one there?”

Rather than telling pedestrians to “go find a safe crosswalk somewhere, even if it’s ten minutes away,” installing signalized crossings in long blocks also provides safe crossings where people already want to walk. Decreasing the distances between intersections also helps reduce speeds.

At the spot on Roosevelt Boulevard in Philadelphia where Latanya Byrd’s niece and three of her niece’s four children were killed, a new signalized crossing was added.

Now safe(r) crossings are half as far apart as they were previously. These crossings might add a few seconds to the average trip through a corridor. But slowing cars to make people safer and provide a new safe way to cross is precisely what it looks like to de-prioritize speed for safety. (Though far more needs to be done to make this incredibly dangerous road safer.)

Lastly, we come to right turn “slip” lanes. These were designed for one reason and one reason only: to keep vehicles from slowing down on right turns. They are incredibly dangerous for people walking. Slip lanes should not exist on any street where people are expected to walk, and possibly on any street ever. We have written about them at length.

Eliminating these slip lanes in favor of right-angle turns produces slower, safer turns and shorter crossing distances for people. They can also create new space for people walking or even sidewalk cafes or other businesses.

View the full animation

You can download the GIF above and share (please do!) and/or embed a slideshow version of this graphic with the code below:

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Wrapping up

Our goal with design should be to make dangerous behavior difficult and safe behavior easy. Designing roads for slower speeds also reduces the need to rely on law enforcement, which not only saves money but also prevents potentially deadly encounters with police for Black and Brown people. 

We will continue to be stuck in an infinite Groundhog Day loop of ever-increasing deaths until the feds, states, metros and cities begin to unwind this deeply embedded, invisible yet powerful emphasis on speed.

It is completely incompatible with safety.

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