4 ms·

I think custom hardware would make sense on custom infrastructure: small 2m wide tracks dedicated to rapid electric transit pods, tucked under and along side th

I think custom hardware would make sense on custom infrastructure: small 2m wide tracks dedicated to rapid electric transit pods, tucked under and along side the main roads. It would simplify the design a lot to the point where you could build it using 80s technology, simple automation, since there are no pedestrians or non-pod vehicles. If you could build the pods on the cheap, cities would love it as an affordable alternative to subway and tunnels - it's much cheaper to dig a 4x2m concrete box under the main road then massive tunnels and stations. In time, as the network expands, full self driving can be added and the vehicles can exit the network and drive the last miles on regular roads to the traveler's front door in the suburbs.

21 8y ago
> it's much cheaper to dig It still costs money. And where should the exits be? If they are far apart this doesn't work. And the prospect of being underground for a long trip is not that thrilling. You're basically proposing a boiling the ocean kind of solution.
- bumholio 8y ago
  It's quite easy to envision some ramps where the vehicle steers out of the main underground lane and ascends on a 20% incline for 10m, stops into a station not dissimilar to any other public transit station, with multiple platforms so multiple passengers can embark at the same time in different pods. When passengers are secure, another ramp takes them back down - or even the same one, with proper synchronization on less busy stops. It would then drive the passengers to any station in the network with almost the same flexibility as a self driving car. I would say the cost differentials to subway are massive, one order of magnitude for similar passenger throughputs. And it's not some unproven, highly speculative technology like self driving cars, it's something that could be built today with low tech (but I concede, high capital investment).
  - Retric 8y ago
    Like most people you vastly underestimate just how many passengers a subway moves. You need to move ~10 people per second through to match a subway's capacity. (2 directions * almost 200 per car * 10 cars per ~5 minutes.) Self driving pods could work but you would basically need to dig tunnels as big as current subway tunnels to deal with the traffic + breakdowns etc.
    - bumholio 8y ago
      At the limit, with proper design a stream of pods can act almost like an endless, continuous train - no subway network can beat that. But even if we accept a 2s spacing between pods, human level reaction times, that's still around 1 passenger per second per lane (with minimal 2 person/pod packing), or 15% of your peak subway estimate per direction. You should also factor the much higher efficiency of a system with no train changes, where the pod occupancy is optimized to avoid those empty returns to the busy area, where you don't have to dig a whole tunnel worth of capacity (6 tracks) at the terminus stations since one is enough for the traffic there, that can dynamically switch track direction depending on demand during the day etc. Bear in mind, a subway tunnel for a single train has a diameter of about 7m, or about ten times the area (and dirt volume to be moved, and concrete to be poured) of a 2x2m lane.
      - hexane360 8y ago
        You're ignoring the near-fixed costs to building tunnels: right-of-way, ventilation, maintenance. Even then, your 2 second gap is a pipe dream, not technically but logistically. You need scheduling flexibility to maintain such small gaps. Whether it's long wait times at stations, long detours to avoid congested routes, or keeping the system significantly below capacity, you can't assume that both a) pods can get on and off at will and b) there's a continuous flow of pods. >You should also factor the much higher efficiency of a system with no train changes, where the pod occupancy is optimized to avoid those empty returns to the busy area How do you avoid empty returns to the busy area? You still need to supply the pods, and if your solution is underfilling pods on the way back, that's exactly the same as sending a light train. >where you don't have to dig a whole tunnel worth of capacity (6 tracks) at the terminus stations since one is enough for the traffic there This is only an advantage at small scales. At higher scales, one train tunnel is just enough at the terminus stations, and the busier routes have more.
  - windows_tips 8y ago
    Running small pods underneath roads doesn't seem like it would really increase throughput much at all, while being significantly harder to build and maintain than the area directly above it.
patrickg_zill 8y ago
Actually a lot of this spending could be avoided if you could convince the government to let you embed a single wire in the asphalt along with some RFID tags. Everything that is expensive and unreliable is because they assume an embedded wire is not going to be allowed/done by the people managing the roads.
- bumholio 8y ago
  That would help surely. But I would say the main problem in this space is not the infrastructure - Tesla meltdown aside - it's the other drivers.
- tomp 8y ago
  Why would the wire help you? If you needed precise location information, couldn't the company just add some markers throughout the city? Either stamp large QR codes on corners and traffic lights, or put thousands of Wi-Fi routers around the town, that would help the vehicle triangulate... The latter doesn't even require permission, just money!
- megaremote 8y ago
  What would that cost on every road?
akhilcacharya 8y ago
My school is working on it - ecoprt.com But it’s NC State and not Top4, so don’t expect anything to come out of it.
voxadam 8y ago
Apart from not being buried what you're describing sounds an awful lot like Personal Rapid Transit (PRT). WVU has been operating their PRT system since 1975. https://transportation.wvu.edu/prt https://transportation.wvu.edu/prt
- bumholio 8y ago
  Sure. Developments in self driving and electric vehicles, ride hailing and general automation make PRT a much more convincing proposal today and a genuine public transport alternative to the personal car, which collective vehicles with rigid routes will never be. All while avoiding the seemingly insurmountable difficulties of fully autonomous driving on congested and chaotic city roads.

21 8y ago

> it's much cheaper to dig It still costs money. And where should the exits be? If they are far apart this doesn't work. And the prospect of being underground for a long trip is not that thrilling. You're basically proposing a boiling the ocean kind of solution.

bumholio 8y ago
It's quite easy to envision some ramps where the vehicle steers out of the main underground lane and ascends on a 20% incline for 10m, stops into a station not dissimilar to any other public transit station, with multiple platforms so multiple passengers can embark at the same time in different pods. When passengers are secure, another ramp takes them back down - or even the same one, with proper synchronization on less busy stops. It would then drive the passengers to any station in the network with almost the same flexibility as a self driving car. I would say the cost differentials to subway are massive, one order of magnitude for similar passenger throughputs. And it's not some unproven, highly speculative technology like self driving cars, it's something that could be built today with low tech (but I concede, high capital investment).
- Retric 8y ago
  Like most people you vastly underestimate just how many passengers a subway moves. You need to move ~10 people per second through to match a subway's capacity. (2 directions * almost 200 per car * 10 cars per ~5 minutes.) Self driving pods could work but you would basically need to dig tunnels as big as current subway tunnels to deal with the traffic + breakdowns etc.
  - bumholio 8y ago
    At the limit, with proper design a stream of pods can act almost like an endless, continuous train - no subway network can beat that. But even if we accept a 2s spacing between pods, human level reaction times, that's still around 1 passenger per second per lane (with minimal 2 person/pod packing), or 15% of your peak subway estimate per direction. You should also factor the much higher efficiency of a system with no train changes, where the pod occupancy is optimized to avoid those empty returns to the busy area, where you don't have to dig a whole tunnel worth of capacity (6 tracks) at the terminus stations since one is enough for the traffic there, that can dynamically switch track direction depending on demand during the day etc. Bear in mind, a subway tunnel for a single train has a diameter of about 7m, or about ten times the area (and dirt volume to be moved, and concrete to be poured) of a 2x2m lane.
    - hexane360 8y ago
      You're ignoring the near-fixed costs to building tunnels: right-of-way, ventilation, maintenance. Even then, your 2 second gap is a pipe dream, not technically but logistically. You need scheduling flexibility to maintain such small gaps. Whether it's long wait times at stations, long detours to avoid congested routes, or keeping the system significantly below capacity, you can't assume that both a) pods can get on and off at will and b) there's a continuous flow of pods. >You should also factor the much higher efficiency of a system with no train changes, where the pod occupancy is optimized to avoid those empty returns to the busy area How do you avoid empty returns to the busy area? You still need to supply the pods, and if your solution is underfilling pods on the way back, that's exactly the same as sending a light train. >where you don't have to dig a whole tunnel worth of capacity (6 tracks) at the terminus stations since one is enough for the traffic there This is only an advantage at small scales. At higher scales, one train tunnel is just enough at the terminus stations, and the busier routes have more.
- windows_tips 8y ago
  Running small pods underneath roads doesn't seem like it would really increase throughput much at all, while being significantly harder to build and maintain than the area directly above it.

patrickg_zill 8y ago

Actually a lot of this spending could be avoided if you could convince the government to let you embed a single wire in the asphalt along with some RFID tags. Everything that is expensive and unreliable is because they assume an embedded wire is not going to be allowed/done by the people managing the roads.

bumholio 8y ago
That would help surely. But I would say the main problem in this space is not the infrastructure - Tesla meltdown aside - it's the other drivers.
tomp 8y ago
Why would the wire help you? If you needed precise location information, couldn't the company just add some markers throughout the city? Either stamp large QR codes on corners and traffic lights, or put thousands of Wi-Fi routers around the town, that would help the vehicle triangulate... The latter doesn't even require permission, just money!
megaremote 8y ago
What would that cost on every road?

akhilcacharya 8y ago

My school is working on it - ecoprt.com But it’s NC State and not Top4, so don’t expect anything to come out of it.

voxadam 8y ago

Apart from not being buried what you're describing sounds an awful lot like Personal Rapid Transit (PRT). WVU has been operating their PRT system since 1975. https://transportation.wvu.edu/prt https://transportation.wvu.edu/prt

bumholio 8y ago
Sure. Developments in self driving and electric vehicles, ride hailing and general automation make PRT a much more convincing proposal today and a genuine public transport alternative to the personal car, which collective vehicles with rigid routes will never be. All while avoiding the seemingly insurmountable difficulties of fully autonomous driving on congested and chaotic city roads.