Road Design vs How People Actually Drive

by Leroy on February 16th, 2023. Last updated February 21st, 2023.

Most people drive automatically. They aren't concerned with driving at all, they are concerned with their destination. Most people don't get in their car in the morning ready to drive, they get in their car ready to get out.

This is a realization that took me a long time to really grasp and caused a lot of anger in me before I truly understood. I would see people make the most bizarre decisions -- braking for no reason causing everyone around them to brake, following much too close clearly wanting to pass yet never doing so, not moving lanes to the right when not passing anyone, fluctuating their speed by 5 or 10 mph rather than maintaining their speed, and much else -- and couldn't help my anger. Nothing major, just idle curses about how this guy should've sped up and that person shouldn't have slowed down so much and how that guy doesn't understand how to merge.

One day, frustrated with my anger as clearly thousands upon thousands of people are not going to suddenly gain these skills, I asked myself why. This is clearly an epidemic, not isolated incidents by specific drivers, so what is happening?

People drive automatically. Nevermind questions of road safety or bad teaching material or overall driving skill. No, people get in their cars and otherwise follow the rules of the road and don't put much more thought into driving while going to their destination. They might turn on their radio or talk on the phone or otherwise be distracted by their own thoughts. For the most part, people drive automatically. You can test this out yourself. Here's some easy exercises the next time you're out on the interstate:

(To be completely honest, simply driving with cruise control will reveal a lot about how people drive and probably make you a better driver, too, because you become more consistent and predictable.)

Why do people drive automatically?

The simple answer is ease. It's a mental burden to think about speed, positioning, and situational awareness for those not disposed. Like I mentioned before, people get in their car to get out. Driving is a means and not an end.

I'm certainly guilty of driving automatically as I'm sure you are too. Any time I've been distracted by a billboard, my phone buzzing, a bad song coming on the radio, the Sun being too bright, or simply exhausted from work, I have driven automatically. People drive automatically for all sorts of reasons because people are human and can't be expected to be on 100% of the time even if we would like them to be.

This is known, of course. Here in the United States, we have fairly rigid rules of the road that are enforced often enough and so people mostly comply. Out of fear, too, most people keep safe distances. We also have some in-built mechanisms that help prevent dangerous situations.

One such mechanism is "all red" time for traffic lights. For a brief moment, all lanes of traffic are shown a red light. It's designed this way so that cars aren't entering the intersection from a green light as soon as another light goes red. This protects any automatic drivers, who don't look in all directions before moving, from any would-be red-light runners.

All of this combined simply allows for automatic driving. We have safety nets. We have intersections with clear rules. In fact, I think 5 or so questions of my 15 question driver's license test was about what to do at a four-way intersection. For the most part, it all works, and with fairly minimal communication too.

Automatic driving is a good thing. For the longest time I disagreed with this statement. I'm not saying that oblivious driving is good. I'm saying that it's good that millions of drivers can go 70 mph, getting as close as just a few feet from each other, and make it safely to their destination every day. That's a good thing and our infrastructure and rules allow it. However, there's a particular bad thing that I feel gets dismissed often when talking about our roads.

Most roads and interstates aren't designed for automatic driving

I think the frustration of traffic is that you can't be automatic. Once I started driving with my cruise control, I found it frustrating anytime I couldn't simply go the speed limit in the right lane. Especially frustrating is when I can't set my cruise control to below the speed limit and just cruise. When there's traffic you have to drive manually. Speed up, brake, speed up, brake. Brake some more, speed up a lot, damn, it's slowing back down -- you get the idea. It's annoying.

Once I started coming to an understanding about how people drive then I could step back and start thinking about what's causing traffic. Why are people slowing down so much in this particular spot? No, this particular exit isn't always backed up because people suck at driving and everyone is stupid, it's backed up because there's something fundamentally wrong about its design.

No, that particular connecting ramp doesn't suck because people should speed up before trying to merge, it sucks because it outputs onto a lane that ends in 2000 feet causing everyone to merge left almost immediately which causes slowdowns. Ideally, the outputting lane shouldn't end at all.

No, that particular interchange doesn't suck because everyone is stupid and doesn't let you merge, it sucks because it doesn't respect the fast and slow lanes. Many interchanges take the slow lanes from one interstate and output them as the fast lanes on the other interstate. A car going 55 mph in the slow lane has their lane morphed into a lane where other drivers expect them to be going 70+ mph. Often, these interchanges merge them backwards! The fast lanes end up on the slow side and vice-versa. How ridiculous, the fast and slow lanes should always be maintained throughout so that the relative speeds can also be maintained.

No, drivers shouldn't have to know, clairvoyantly, that they need to slow down for this upcoming ramp. It is poor design to have a harshly curved ramp where one needs to slow to 25 mph off an interstate which has a speed limit of 70 mph. If changing the ramp to be safer isn't an option, there should at least be a lane specifically for slowing down over time lined with as many obvious caution signs as possible.

No, traffic isn't bad at this particular junction because people just can't drive, the traffic actually backs up because it connects two major interstates and forces drivers to cross four lanes of traffic to make their connection. So many cars all making the same four-lane cross inevitably causes slowdowns.

Roads should be designed around how people actually drive. This was such a big epiphany to me that I almost always bring this up whenever people share their opinions about road design. Often, I'm heavily rebuffed. The roads aren't badly designed, it's everyone else, I'm told. If they simply merged correctly or sped up or let them over then the problems would go away. Everyone else is always the bad driver in everyone's story.

I encourage everyone reading this to really pay attention to why you encounter the same problems at the same pain points on the road every time you drive on them. It's fairly eye-opening and you may be able to make a persuasive argument to your local government for fixing them. But perhaps save those arguments for emails and letters to your local politicians -- this advice won't make you a winner at the next cocktail party.