How Street Design Shapes the Epidemic of Preventable Pedestrian Fatalities

Memphis Union Ave aerial combined

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 to 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: 

  1. Expect to see and yield to people outside of vehicles, and

  2. 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 the 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.

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