Want Safer Streets? Human Psychology Might Hold the Key

It's been a while since I've entertained my readers with awesome transportation stuff - life has been a little hectic, and I haven't made it a priority to write. Hopefully we can change that!

The United States has some incredibly dangerous streets. Despite rapid advancements in vehicle safety technology, the US notoriously has fallen behind other developed countries in keeping road users safe. In fact, the US has the highest per capita rate of traffic deaths among the high income countries (see figure 1), and has consistently been underperforming compared to peer countries. We have an epidemic on our hands. 

Figure 1: The US has the highest motor vehicle crash death rate compared with 28 other high income countries. Credit: CDC (link)

This epidemic is most prevalent for some of our most vulnerable road users - pedestrians. While the rest of the developed world has managed to dramatically reduce their pedestrian fatality rates, it has actually increased in the United States. Indeed, this is the opposite of progress. In the United States, roughly 20 people per day are killed while walking (GHSA, 2022). 

US pedestrian fatalities are on the rise, despite continued decreases in other countries. Source: Buehler and Putcher, 2023 (link)

It is clear we need to do something to stop these deaths. Walkable cities rule, and we need people to be able to walk places for cities to be vibrant, financially productive, healthy, and sustainable. However, these deaths and hostile pedestrian environments create a massive barrier to creating these amazing places. 

So how can we reduce these deaths? To understand this, let's take a little look into human psychology.

Let's Talk About Risk

Everybody has their own tolerance to take on risk. Some are risk seekers, some are risk averse. Levels of risk are communicated to us through our built environment, and individuals implicitly compare the risk communicated to them by their environment with their natural risk tolerance. 

If the built environment communicates a level of risk that is below your risk tolerance, this creates a risk gap. When there is a risk gap, you find ways to fill that gap. In the context of driving a motor vehicle, maybe you will drive faster. Perhaps you'll send a text message, take your eyes off the road, change the radio station, etc. This is all because the environment is communicating a level of risk that is lower than your risk tolerance. The natural tendency is to fill this gap.

Think about this: we all know a street in our hometown where the speed limit seems awfully low. The speed limit might be 25, but the street lanes are wide, there might be a recovery zone on the side of the road in case you lose control. Maybe there's rumble strips. In the context of this environment, the environment is communicating a low level of risk - one that is far below your risk threshold. The natural reaction here is to drive over the speed limit because you feel comfortable doing so.

The issue with American streets is that they are designed to forgive common mistakes of drivers. As Chuck Marohn (2021) describes in Confessions of a Recovering Engineer: Transportation for a Strong Town,  we design streets with wide lanes so if people drift, they won't hit another driver. We add clear zones on shoulders so you can regain control of the vehicle if you lose control. This is all well and good, but such road design often fails to communicate an appropriate level of risk to drivers that fits the context of the environment. 

Say an environment has a lot of pedestrians, but the streets are designed in the way described above.  The complexity of pedestrians, cyclists, and cars interacting together creates some level of risk. However, because of this forgiving street design, the appropriate level of risk and complexity is not communicated with drivers, and they are encouraged to fill their risk gaps in a way that is detrimental to the safety of pedestrians. I think you can see this is a recipient for disaster.

While on a walk today, I came across the perfect example of the risk tolerance / perceived risk/ actual risk tradeoff. On Detroit Ave and Lake Ave, there is a right turn that is more of a "slight right". Because of the wide, sweeping, smooth curve, drivers feel very comfortable proceeding through this intersection at a high rate of speed. The environment is communicating a level of risk that is below most people's risk tolerance, so drivers fill their risk gap. 

The pedestrian killer. The sweeping, gradual right turn signals a low level of risk to drivers and encourages them to act in a manner detrimental to the safety of pedestrians.

The problem is that at any moment, a pedestrian could be trying to cross the street. This creates risk that the street design does not communicate to the driver. Drivers are encouraged to act in a way that feels safe for them, but in the context of the environment, is indeed unsafe. Pedestrians trying to cross here are moving targets. This sort of street design kills pedestrians. 

Let's call them what they are - pedestrian killers

As I was trying to cross here today, three cars failed to yield for me at the crosswalk, despite me having the green walk sign. They all proceeded through this intersection at a rate of speed that would have certainly caused serious bodily harm to me if I were hit. I felt extremely unsafe. 

With this lesson in human psychology, how can we make streets safer for pedestrians?

Make drivers feel uncomfortable acting in a manner that is unsafe for pedestrians

To make streets safer for pedestrians, we need to design the street so the appropriate level of risk is communicated to the driver. We need to close the risk gap.

The key is to design the street so that drivers feel comfortable operating their vehicle safely, and uncomfortable operating in a way that is unsafe (Marohn, 2021). Current street design makes drivers comfortable operating in an unsafe manner. We need to change that.

For the Detroit/Lake intersection- tighten up the curve. Maybe add some bollards. Narrow the street. If all these things are done, this communicates more risk to drivers, which closes their risk gap. Therefore, they will proceed through this turn much more carefully and safely. 

A better solution. Now, drivers will feel uncomfortable driving in a manner that kills pedestrians, and will feel comfortable rounding the corner safely

Vision Zero is an idea that we should have 0 deaths on our roadways. Understanding how the human mind works, and designing streets with this in mind, will help us get closer to that goal. Let's make it happen.

Sources:

Buehler, R., & Pucher, J. (2023). Overview of Walking Rates, Walking Safety, and Government Policies to Encourage More and Safer Walking in Europe and North America. Sustainability, 15(7), 5719. https://doi.org/10.3390/su15075719

Governors Highway Safety Association. (2022). (rep.). Pedestrian Traffic Fatalities by State: 2021 Preliminary Data. Retrieved April 1, 2023, from https://www.ghsa.org/sites/default/files/2022-05/Pedestrian%20Traffic%20Fatalities%20by%20State%20-%202021%20Preliminary%20Data%20%28January-December%29.pdf.

Marohn, C. L. (2021). Confessions of a recovering engineer: Transportation for a strong town. John Wiley & Sons, Inc.