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Comment by general1726 | Hacker News Reader

Well then you will find out that these vehicles needs their own infrastructure, because they don't exist in a vacuum, but in a city where lot of other elements are using the roads, like people crossing streets on lights.

And when you will get your own infrastructure, well you are converging back to a subway or overhead light railway.

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No you don't have to converge to that. Railways and trams tend to be defined by track switching. In-car switching creates a different class of system as the track is dumb, headways can be much tighter, and with a network of rails you don't have to go to a central hub, to go to another central hub, to then go to where you actually want to go.

Stations can be frequent and offline, individual transports can be smaller to transport a family / sleeper car / pallette-load of goods, land use under the track becomes available ie. new routes over farmland become viable, tracks can cross easily in 3D, and can as they are prefabbed, a line can be constructed and repaired quickly.

Although it's (IMHO) not ideal, https://openprtspecs.blogspot.com/2011/11/climbing-chain.htm... can give you an idea of the possibilities.

You are just creating an expensive infrastructure for few individuals. If you want to justify the cost, you need to push as many people through it as possible. And most efficient way to do that is train. Thus every pod nonsense will get converged into a train or train like setup.

Couple of things here, you're discounting completely the effect of distributing the passenger load across a network, secondly there's no reason why small minicars can't run on the network on high-traffic routes in addition to the smaller ones.

The important points are:

Point-to-point unlike trains (hub-hub) and busses (every stop). As a result, load is distributed across the network. Small offline stops like busses. Complements other systems (tube, freight trains etc.) - if you can separate freight from passenger rail that's a massive win (eg. capacity, schedules). In-car switching lowers headway, does not require centralised coordination. Cars do not need to park - recycled on the network. Sleeper cars. Cars can go direct from warehouse to local shop, as the small cars can berth inside the warehouse/shop for loading/unloading. Power supplied in-track, possibly with backup batteries, but not neccessary depending on implementation. Separate track from pedestrians etc. Prefabbed track for quick build-out and maintenance. Rail and road require preparing the surface rather than driving poles into the ground. Separated steering, load, drive systems, unlike rail which has to compromise with a single conical wheelset. No derailment. Tighter turning than busses and trains, so you can fit it where they cannot go, note we don't always need to run at high speeds in cities, only intercity. Suspended systems can easily tilt - better ride comfort and tighter turning at high speed. Weatherproof, more so than bus or rail. More tolerant of natural disasters if above grade (flooding, earthquakes etc). Better land use if pole-mounted, lighter cars (say 20 people max) than light rail allows lighter-weight structures, and hence lower wear and noise. Heavy vehicles wear roads and rail much faster.

Dumb cheap rails, only power, no switching or coordination. This is a big cost for trains which need to rely on slots and schedules. Coordination is done via protocols to allow for decentralised on-demand use. 3D track allows say transport to halfway up a building. If you have dual-size compatibility (big and small) this allows individual parcel delivery, recycling collection, use in factories etc. with the small system.

Conventional trains cannot do any of these things (tilt is not as good). Yes they are THE most efficient at transporting large numbers of people / freight from eg. the Superbowl, but history has shown they are far from a complete solution.

The features I'm talking about here are not gadgetbahn ideas, they are real advantages for what is a new system, not a car, a bus or a train. This can complement existing systems. Cost is a misnomer when you factor in switching and coordination for busses and rail. Last mile becomes much less of a problem. Pitching a more personalised transport is easier. If you standardise the track and protocols you can have many companies building it. You can run fibre, power, solar panels (if suspended) in the same track for infra buildout in 3rd world countries.

For comparison, the numbers for an example system: At full occupancy (which seems to be what everyone quotes for rail, discounting economies of running routes off-peak etc.) 20 people with 10sec headway = 7200 people /hour on one rail. If we say we can fit 2 rails per train rail width-wise and another 2 heightwise, that's 28800 people down the same railtrack profile, which is comparable.

This is also leaving out platooning eg. Virtually coupling 2 cars together, so slightly longer platform which doubles your throughput to 57600. This is different to a train as platooning is a temporary arrangement.

Given a 2min loading time, you would need say 12 platforms to support this from a single station, but that's normally aggregated from multiple stations funneling into the same track, so you'd only require that at terminuses for instance.

> you will find out that these vehicles needs their own infrastructure, because... people [cross] streets on lights.

Isn't handling that part of the definition of "self-driving"?

People repeatedly crossing lights will create traffic in the city, self driving or not.

Using your own infrastructure negates what self driving tech bros are trying to achieve - pods on existing roads.

Your vision for public transportation sounds like "trains, walk, bike, or gtfo".

There's 0 room for buses. If someone lives 2 miles from a train station and can't bike, too bad.

Maybe you don't mean that, but it sounds like that to me. Please explain how last-mile connectivity works in your world.

This edge case always comes up as counter argument to better public transports and cycling infrastructure. The few who can't combine walking or a bike with some form of public transport will simply rely on less efficient modes of transport on the now much less busy roads... be it a (small) car, a shuttle, a taxi, or whatever makes sense.

It'd be silly to suggest we don't need escalators because the elderly only use the elevator anyway.

> The few who can't combine walking or a bike

Outside of dense metros, getting to the nearest bus stop or train station (note: nearest, and not necessarily the one you need for that trip) entails a minimum 10 minute walk. Most people don't live in NYC where you climb down from your apartment and board the bus/subway. Add on a 10 minute walk at the other end of the ride as well, and some waiting for the bus or train, and your trip is already 30 minutes long without going anywhere.

So then you resort to biking to save time. Even assuming 100% of the population can bike (not true because elders, small children, people with disabilities etc.) buses only have 2 bike racks. Trains are somewhat better but even they don't have space for everyone's bike.

Train-heavy solutions work best in dense urban environments. Most of North America is not like that. You need complementary modes of transportation. They aren't for "edge cases". They are a holistic solution that makes the entire system accessible. A train is useless if people can't get to it easily. If there are frequent, fast bus routes to get people around then train ridership goes up too. It's not a competition.

Even in a place as dense as manhattan (where I live), it’s very common to spend 30 minutes on your commute still between walking to/from the subway and waiting for the train. Without sounding too harsh, a 20-minute walk really shouldn’t be a major hurdle for the vast majority of working adults.

Whenever I visit other parts of the US I’m struck by how resistant people are to walking even half a mile in the best of circumstances: wide, well-lit sidewalks etc. It’s remarkable how often we default to driving for trips that clearly don’t require it, and it’s like I’m speaking heresy for even suggesting it when visiting somewhere that has pedestrian paths.

At the heart of the public transit debate, it seems, is a simple reality: Much of the country simply doesn’t want to move at all, even short distances. Suggesting someone walks half a mile sometimes feels like suggesting they run a marathon. All the pedestrian infrastructure in the world won’t change that.

> a 20-minute walk really shouldn’t be a major hurdle for the vast majority of working adults

Most US adults live in suburban or non-dense cities. In the 20 minutes it takes to walk to and from the bus stop they can complete most of their trips in a car. Driving is the competition. Walking per se isn't the problem. The time it wastes is the hurdle.

> Even in... manhattan... it’s very common to spend 30 minutes... between walking to/from the

And that's an acceptable tradeoff in Manhattan because driving the same distance would take twice as long and be 4 times as expensive.

If you are not a bed ridden, you can walk from a stop to your home. Solution does not need to be perfect, it just needs to be acceptable (price and capacity) for most of people and pods aren't either cheap nor have enough capacity.

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