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Comment by itishappy | Hacker News Reader

Is it? "Large blocks of vehicles moving in tandem" is a technology we have today: trains. Are trains that bad for pedestrians and bikes?

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No, because they're confined to completely separate tracks, which they don't share with pedestrians or bikes at all. In fact, when the two meet, we call it a "train crossing" and have special "cross guards" to keep pedestrians, bikes, and other vehicles well away from the train. Otherwise, we generally try to keep the tracks away from other modes of transit, by either putting them in tunnels ("subways") or elevating the tracks, or just not putting them near roads to begin with and giving them special right-of-way.

None of this resembles the way we treat cars at all.

I guess different countries have different rules, but my country have classes of roads which are not shared with pedestrians or bikes. There are generally not that many traffic lights, but there are exceptions.

The biggest use of simultaneously acceleration in those situations would be around road maintenance and other situation where road speed or number of lanes are reduced, with heavy congestion as a result.

As both a driver and a pedestrian I would love that engineering solution.

PLEASE build human scaled walkways _away_ from roadways. In my climate zone, please also provide roofing over them to shade from solar and downpour events.

Crosswalks. The "car crossings" for pedestrians and bikes are called crosswalks. They're dedicated sections of road, typically selected for high visibility, specially demarcated and often even specifically signaled. High-speed traffic is generally kept away from other modes of transit by means of elevated highway sections (in high-density areas).

My dude, this is literally exactly what I had in mind.

The intersection of paths taken by pedestrians and trains is much more limited than that for pedestrians and cars.

And notably, trains don't stop for pedestrians.

Or another way:

Roads are a shared resource. Train tracks are not.

You mean the trains that go by once every 15+ minutes, and are confined to a track with no way for the operator to do anything but brake or speed up, compared to every few seconds with the ability for the driver to take control at any moment?

But I guess this would work/be status quo for non-autos if we kept the signals so peds and bikes knew they could still cross and probably not get run over by someone who decided to switch back to manual control.

> You mean the trains that go by once every 15+ minutes, and are confined to a track with no way for the operator to do anything but brake or speed up, compared to every few seconds with the ability for the driver to take control at any moment?

Yup, those trains! They'd have a shorter and more irregular schedule, but autonomous convoys would behave pretty similarly to that. Outside of emergencies like drivers assuming control to swerve into pedestrians, I guess.

Plus, like you say, no need to remove any of the infrastructure of really safety assumptions of today, just augment.

how many pedestrians and bikes are directly crossing busy train tracks at grade? traffic lights signal cycle every minute or so.

the issue is that unlike trains, roads are so numerous that they are hard to avoid, and it is financially unrealistic to bridge or tunnel for non-motorized users across every road, particularly if you want that crossing to be accessible.

> how many pedestrians and bikes are directly crossing busy train tracks at grade?

Near me? A few. Not sure how busy, but I get caught on my commute about once a week.

While I totally agree with your points, I don't see how this is any worse than today. Connected convoys don't need to go at every green light (like that one robot planet from Futurama) they can wait for pedestrians. The biggest difference would be clearing intersections quicker.

You say it would not make things any worse and I disagree.

If anything, it might codify how hostile parts of the US already are to pedestrians, with beg buttons that may or may not work properly. More efficient cycles with less gaps may give people even less time to dart across during a cycle where they may not have the green but there is no cross traffic.

If traffic clears the intersection faster, you can have more efficient cycles without changing the cycle time. The effect would be larger, not smaller, gaps.

That would assume that transportation departments in the US would step away from trying to boost car throughput at all costs. That’s their current MO; car travel is like a gas that expands to fit all available space.

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