Photo by Herson Rodriguez on Unsplash

Why Does Parallel Parking Always Involve Reversing?

Cindy and I were driving around in the Marina District of San Francisco looking for parking when I noticed someone entering a parallel parking spot nose-first. I said to Cindy, “You know that’s going to end up in tears: back-and-forth, back-and-forth.” I then proceeded to explain to Cindy why it works better to back your car into a parallel parking spot. It’s not something she had understood before, perhaps because she had never really thought about it. I wasn’t even aware that I knew why head-first parking was a problem. Maybe I didn’t: I have often driven my car head-first into parallel parking spots. I suspect that it’s something that most people don’t understand simply because they don’t think about it.

A few days later, I was having dinner with the CTO and co-founder of Cabin, “The dreamiest way to travel between LA and SF” who happens to also be my friend. He was a kid-genius who invented automatically-orienting solar panels before he was sixteen and then sold his intellectual property for a ton of cash. Not sure if my revelation about parallel parking was obvious, I asked him if he knew why it works better to back into a parallel parking spot. He didn’t, so I proceeded with my now practiced presentation. After discovering that even Tom didn’t know, I then revealed that I was considering writing an article about it.

Tom said, “There’s not really enough there for an article.”

“You don’t understand,” I responded, “I can take the most boring and mundane idea and flesh it out into a whole article, replete with diagrams and a compelling narrative.”

So, with all of that said, let’s get started. The key thing to realize about a car is that only the front wheels can be steered. That’s true, at least, for most cars. This means that the front wheels control where the leading edge of the car goes. When a car is driving forwards, the front wheels control where the front of the car will go, and the back wheels simply follow. However, when a car is going backwards, the front wheels are directing where the back wheels will go.

The trick with parallel parking is to first get the back of the car up against the curb. Then the front of the car can easily be swung into place. This is why it’s always best to back the car in. The steerable front wheels push the hard-to-maneuver back of the car and set it in place first before they are used to place the front of the car.

If you start parallel parking by driving the nose of the car toward the curb, you end up with the back of the car too far away from the curb, perhaps even a whole car-width away. Then you have to try to get the back wheels in. Inevitably this leads to an attempt, whether recognized or not, to get enough space behind the car to reverse it so that the front wheels can be used to finally push the back of the car in.

Once you’ve entered the space the wrong way (front first), then the back of the car is already further out than the front of the car, so then most of the effort will spent trying to get the front of the car away from the curb again by any amount so that it can be used to push the back wheels in. Basically, it then become a process of trying to actually reverse-park, but starting with the car oriented exactly the wrong way, and with very little space in the rear.

This leads to those familiar little micro movements back and forth: (1) get the front wheels a little further from the curb than the back wheels; (2) push the back wheels in a little until there is no more reversing space; (3) drive forward again and go back to step one. At this point, it’s usually better to just give up, leave the space, and start again.

Not having thought about this in depth before, I have often seen what looked like a long space against the curb and happily driven front-first into it, thinking, “Oh there’s loads of room. I don’t need to reverse into this one.” Then I’ve spent five minutes edging the car back-and-forth to get the back wheels in. I have often taken this false short-cut because I felt bad about making people wait for a few moments while I backed into a space.

Unless you can drive forward along the curb for many car lengths, gradually moving the back wheels towards the curb, it’s never worth parallel parking without starting by reversing. Once this is understood, it seems obvious of course. And it’s okay to make other drivers wait for a moment while you park.

An engineer-psychologist focused on machine intelligence. I write from my own experience to support others in living more fulfilling lives |

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