You CAN engineer streets for calm driving.
We're too quick to dismiss factors that influence reckless driver behavior, especially when very credentialed professionals are part of the problem.
A motorist speeds when their foot presses too far on the gas pedal. Yes. But there are lots of factors that play a role in our driving habits.
Ironically, a whole bunch of car features that were developed to make us feel safe lead us into danger. Automatic transmission, power steering, anti-lock brakes, seat belts, and airbags are just a few.
People take more risks when they feel safe.
Trade-offs are everywhere, even with vehicle upgrades meant to protect you. The same is true in the design of the built environment. The stuff we see (or don’t see) through the windshield influences our driving behavior.
Large and small trees
Benches and bus stops
Building styles, heights, and location
Placement and size of street lights
Width and number of car lanes
Width and separation of bike lanes
The more stuff there is, and the more squished you feel as a driver, the slower you drive. This should be plain as day. In a crowded environment, you probably lean forward to the steering wheel and hunch your shoulders. In a spread out landscape, you accelerate while scrolling through Facebook.
Design influences behavior, so engineer for safe driving.
Here’s a summary of my opinion: design street networks for the travel behavior you want. Why is this so controversial?!
Last week I tweeted about the engineering influence on speeding, and you might say it stirred emotions.

Speeding cameras, at their best, are used to discourage reckless behavior. Rather than snagging an occasional speeder, they spot and immediately fine every single speeder. Funnily enough, even agencies who acknowledge speed kills give a buffer. Philadelphia tells you up front you can set cruise control to 10mph over the speed limit and be okay.
So back to the mind wandering exercise. What if the licensed engineer who approved the speed-inducing design was on the hook to pay 10% of a speeding ticket? Or the engineer’s employer. It feels unfair at first because a driver is ultimately responsible for their actions.
But are you willing to ignore the factors that influence speeding?
Bad driver behavior starts in the engineering office.
Here’s the thought process in the traffic engineering department:
We designed this street at 10mph above the speed limit, for safety.
Everybody's driving 10mph above the speed limit.
We recommend raising the speed limit, for safety.
Now that the speed limit matches the design speed, we recommend re-designing the road to be 10mph above the new speed limit.
Leading up to the ribbon cutting for new infrastructure, the local press makes a couple calls to identify the engineer of record. In no time they’ve got a photo shoot and interview lined up.
Then crashes start piling up on the “improved” street. The local press wants to know what’s happening, after all, the experts just cut the ribbon on this newer, safer infrastructure. Where’s the engineer of record? Poof. Nowhere to be found. Oh well.
The professional engineer who stamps road designs isn't the only one who acts like the meme above. It's human nature. But they do act like this.
When a road project gets an award, the lead engineer is often named specifically and will get a copy of the trophy. When a road project makes news for its awfulness, the lead engineer is nowhere to be found and fingers are wagging at politicians.
There's always a team, and there's always an agency that approves. I've just been thinking about accountability. What if you start with the boss who stamps the drawings and signs it as the approving professional engineer.
There’s plenty of opportunity to engineer safer streets.
Every time surfaces are repaved, new site plans get reviewed, new lighting & street tree proposals come through... there's constant tweaking of networks. The problem is the default habit of clearing, expanding, and straightening. You shouldn’t be surprised at the outcomes any more than you’d be surprised at what happens when a 16-year old gets behind the wheel of a V8 sports car.
If something like "fine sharing" was attempted at the smallest scale, word would spread lightning fast. There'd be passionate op-eds, for and against. Local press would cover the controversy. But the bottom line is the issue would get attention.
My goal is for people to wrestle with the link between design and behavior. Fortunately, there are ways for professional engineers to design streets for calm driving.