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Comment by lefrenchy | Hacker News Reader

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One of the major problems with cars is the terrible lack of density. Per-occupant, a car occupies more space on the roadway than any other form of passenger transport. And as cars get larger, that lack of density gets even worse. There's only so much space on the road, so something has to give.

When I look at traffic in my city, I rarely see it caused by full packing. Rather throughout seems to be the issue.

Throughput is directly proportional to the volume of cars, and SUVs have larger volume. Technically perhaps surface area, but there is a psychological effect to height. I believe people also give taller vehicles more space as a rule.

Throughput in congestion is determined mostly by how quickly drivers react to the opportunity to move and how many points of attrition are in a path. Both of what are impacted by the number of cars and how well they break or accelerate, not by their size.

There's space to claim large car cause attrition, but that's completely dependent of the local properties of the streets.

The footprint of the car matters. When cars get 5% longer, the same number of people in cars takes 5% more roadway, which adds up quickly, because the difference between smoothly-flowing traffic and jammed traffic is a fragile equilibrium dominated by breakpoints. Furthermore, heavier cars accelerate and decelerate slower than lighter cars, which has a compounding effect on decreasing overall throughput.

That isn't true. Most of the space a car takes is empty as you need long distances between cars.

No, the length you need between cars is variable and depends on the speed of traffic and the time it takes for a car to come to a stop. The longer a car is, the heavier it is (frames do not have negative weight), and the heavier it is, the longer the stopping distance is. Please don't bother commenting further on something you're so belligerently clueless about.

That larger cars cause diminished throughput is pretty solidly demonstrated through a variety of modeling and real-world traffic analysis.

https://www.researchgate.net/publication/365069344_How_the_r...

Here's a helpful comparison https://www.carsized.com/en/cars/compare/opel-astra-1998-cou...

That's an amazing website; thanks for linking it. Apparently, lengthwise, my car easily fits between the wheels of a Ford F-150 without even touching them. My car's full height is substantially below where the F-150's windows begin. That car could probably drive over my car and barely even notice it.

Not so helpful; the cars are from two different generations at two different price points. Try https://www.carsized.com/en/cars/compare/bentley-flying-spur...

You're calling out different price points while then choosing a $200k car. Which, you picked that car because it's an exceptionally long sedan.

How about we choose a different SUV?

https://www.carsized.com/en/cars/compare/bentley-flying-spur...

I see far more suburbans on the road than all models of Bentley.

People aren't choosing SUVs because they're smaller than sedans. They're choosing them because they're bigger.

Here's comparison with Albarth https://www.carsized.com/en/cars/compare/abarth-500-2016-3-d...

Here's Audi A1 (I used to drive this one, including taking another person and a kid on a ski trip): https://www.carsized.com/en/cars/compare/audi-a1-2018-5-door...

Volvo's own insanely huge and long V60 is still shorter than XC 90 https://www.carsized.com/en/cars/compare/volvo-v60-2018-esta...

Because old and new cars never have to interact on the road?

Also why are front and rear not overlays

Have you ever tried to park an SUV versus parking a sedan?

Great point.

Additionally, driving a small sedan myself, if there is a parking spot (not parallel, normal lot spot) in between two SUVs, there is a good chance that spot is useless, even in my small car.

Just last night, I was parked perfectly (I had to stop and admire my work because what follows), but still had to squeeze out with my door undoubtedly touching the SUV, and it wasn't even a large size SUV.

I really hope waymo takes of and makes it economical to stop owning a car, and reduce the necessity of parking lots

> there is a good chance that spot is useless, even in my small car.

Totally off topic but I've seen two smarts side-by-side in one parking spot, on a right angle to the parking spot making exiting the spot easy. Now that's efficient. And they still were less parked on the road than any big SUV or worse.

Here the large SUVs make everyone else drive slower in the city, because they're so big the driver has poor visibility and thinks they need several feet more than they do in clearance, and so drive almost in the middle of the road. Others then have to go real slow to not get dinged up on either side.

You have a fixed amount of space to put stuff. If the stuff gets larger, can you put more or less stuff in that space?

So now we have at least the same number of people trying to put their stuff in that fixed size space, but their stuff got bigger, does that make it easier or harder for them to put their stuff in that space? Will they have to compete more or less for that space?

Seems like a pretty obvious one to me.

fewer cars per foot, less visibility, etc? If there's a sedan in front of me I can see whats going on, if there's a UPS box truck, i cannot even see the light 150 feet away.

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