Imagine if half of the cars in traffic were gone. Imagine your glorious morning commute, zipping along at 70km/h in what used to be gridlock traffic. You look out the window immediately to your left and see something you’ve never seen on your commute before: the scenery rolling past you at the speed limit. You look out the window immediately to your right and see something else you’ve never seen before: a window immediately to your right.
What is this? Is this the edge of the universe, contained in the driver’s seat of your car? No, this is the solution to traffic. This is another one of my Mostly-Baked Ideas™.
Sometime between one and infinity years from now, there will be lots of autonomous cars on the road. While this may eventually help solve some problems like safety and accessibility, it probably won’t help solve the congestion problem. In fact, it may make it much worse. There are, however, some ways that autonomous vehicles could mitigate congestion. Platooning is one; this is where AVs take advantage of their much quicker reaction times by driving very close to each other. I have a similar solution.
Rush-hour traffic is filled with one-occupant cars. Here in Southern California, there are four lanes of one-occupant vehicles and one car-pool lane that is half-filled with one-occupant electric vehicles. There are 1.59 people in a moving car in the United States on average, and it is lower during rush hour when traffic is the worst.
If the often promised future of autonomous ride-hailing comes to be, fewer people will own cars. Many will ride in autonomous cabs that will have one purpose: to move one, or occasionally two people through traffic.
Many, if not most of these cars only need two seats. They could go the Smart Car route and just get rid of the back seats, but this is less than ideal for a couple of reasons. Crash safety requires a crushable distance of about half a metre in front of the occupants. If you have two rows, you only need that distance once per two rows of people, so the total area that tandem seating cars take up would be less.
You could also have the cars closer together side-by-side than you would front to back, because of the motion of travel; your moving inertia is mostly forward, not sideways. The cars could be very close together, especially if they are communicating with each other.
This configuration also maintains the usability of parking lots and garages, and doubles the number of usable spaces. Parallel parking would take up half the space, so now you can add another lane. Loading and unloading areas will be smaller and can fit more lanes, which will help alleviate congestion after events like sports or concerts. So much traffic throughput!
At this point, some of you are looking for a GIF of a car tipping over during an aggressive turn to post in the comments.
Won’t they tip over? No, and here are two reasons why not: Electric vehicles (which these vehicles will almost certainly be) have very low centres of gravity, largely due to the batteries being mounted under the body. Porsche claims that the Taycan has the lowest centre of gravity of any car it has ever made. Tesla claims they had trouble getting the Model X to roll over in its initial rollover tests.
Also, with autonomy, the vehicle will have improved reaction time that will help it to avoid abrupt manoeuvres or react to them in a way that mitigates rollover risk.
What if you’re with your child, or you want to talk to your passenger? Simple: boat seats. You know boat seats, they have a back that flips forward or backward so you can face either direction. Just make the front seat a boat seat and let the front occupant choose at the beginning of the ride. You can also leave both seats facing forward if you are sharing a ride with a stranger, or you want to pretend you are in a fighter jet.
As with all ideas of any kind, a quick internet search reveals that I’m not the first person to think of this. There have, of course, been several proposals for half-width cars from car companies, movies, and unhinged bloggers, though most of these have steering wheels. I think autonomy is really needed to make this work, and with all the research and money going into autonomy, I believe now is the time to earnestly pursue this idea.
Sure, we need some higher occupancy vehicles for families or large groups, but this is the correct setup for most autonomous cars. Any other configuration for one or two occupants is a waste of road space, an unnecessary use of half a lane decreasing our throughput to half of what it could be.