Comments so far are not discussing what makes this light rail “very” light, so here’s an excerpt. The project claims to cost half of “normal” light rail.
> The vehicle is battery-powered, eliminating the need for overhead wires. It features an innovative turning system, enabling it to handle 15m radius curves. This allows for installation in tight corners within the existing highway. The Council intends for it to operate at a high frequency, providing a turn-up-and-go service. The vehicle has a capacity of 56, is comfortable and has low floors to enable passengers to embark and disembark easily. The vehicle has been developed to allow autonomous operation in future.
> The new track is laid just 30cm within the road’s surface, minimising the need to relocate pipes and cables, which is time-consuming and expensive. It achieves this by leveraging cutting-edge materials science, while still utilising standard rail parts to ensure ease of manufacture.
These things are tiny! I've traveled in larger airport shuttles.
It feels like that's putting this into a really awkward place in the tradeoff space. Trams work because they can scale higher than buses. That scale comes at the cost of more up-front infrastructure, much less flexibility, and needing dedicated lanes. So cities don't have trams everywhere, but they're only installed on routes that can support the scale.
For these you still have the up-front investment (just less of it) and inflexibility, but don't get the efficiencies of scale due to how small the capacity is.
Is this really just a bet that they can get autonomous tram-driving on city street approved a decade+ sooner than autonomous buses?
Tiny might make sense if they are running every 2 minutes and thus getting their capacity via frequency. However there is no reason to think they will do that. (if they were running anywhere near that frequent overhead wire would be a lot cheaper than a battery on every tram)
I didn't really mean that they needed higher capacity. If they had the passenger volume to justify such high intervals, they'd already have real trams.
But rather, this is giving up the benefit trams have over buses, without gaining any new edge to replace it. So why is it a good tradeoff? And why now, not 20 years ago?
The autonomous driving angle is the only idea I have.
Trams don't actually scale higher than busses; the highest ridership BRTs have far more ridership than the highest ridership light rail. The key thing that makes it work is having a dedicated right of way. I expect busses get a bad rap as a scaled transit solution mostly because they have to share the roads so often. But it's indeed an advantage of light rail that it's a lot harder to make that mistake with it.
Besançon in France is one of the cheapest conventional tram schemes in Europe at €17.5m per km and €1.81 per tram (132 passengers). It’s a conventional tram track with overhead catenary wires: as standard as one can get with those things. Presumably in the UK the costs would be somewhat higher: France is a modern tram capital, with a lot of relevant talent and expertise available locally.
I haven’t found the projected figures for Coventry but it would be very, very awkward if they can’t beat the numbers above with a supposedly much cheaper track.
Everything old is new again: The Light Railways Act of 1896 also propsed rail lines built to less then mainline standards (often narrow gauge) to get transport links to otherwise unconnected locations. https://en.wikipedia.org/wiki/Light_Railways_Act_1896 comment edited because I fat finger editing the submit button
Gadgetbahn - a derisive term transit advocates use for something that claims to be innovative but in fact doesn't do anything not thought of before and doesn't solve any problems.
They make all kinds of claims that don't stand up to over 100 years of history running trains. The claim they are innovative, but there is nothing new here, and no evidence they have looked at the real problems of transit systems. Someone is going to make a lot of money on this at the expense of the community that loses.
Trains have been around for a long time. You can buy all the parts you need for a good system off the shelf. You won't be saving money by designing something new, you just waste money on engineers to design something and then lose the scale factors you could get from buying the same thing as everyone else. If you buy the same thing as everyone else that means there will be a market for spare parts and thus in 20 years when (not if!) something breaks you can keep the system running.
Yes overhead wires are expensive - but they are a rounding error compared to track. Batteries are expensive too, and you have to buy a lot of them. Batteries need to be recharged which means these trams will be out of service often so they have to buy a lot more so that when one is out of service for charging the others can work. (you still need a few extra for maintenance, but battery charging is more common so you need a lot more)
If you want to build a train the best way to save money is to build exactly the same as everyone else does: standard off the shelf trains, running on standard off the shelf rails, and standard off the shelf overhead rail. If you want to innovate make sure that everyone is fluent in Spanish, Turkish, Korean, or Italian - because places where those languages are spoke build and run trains much cheaper than other places you can think of so you want to learn from them. (note that French or Japanese are not on the above list - while those areas do cheaper than English speakers, they are still expensive)
I'm not sure about the UK, but in the US most of the cost blowout for trains seems to be in stations, so focus all your innovation there: don't make them monuments to how much money you can spend. (The UK has cost problems almost as bad as the US, but I'm not aware of any study on where the issues come from, while at least in the US there are studies).
Unfortunately the Coventry VLRT is all about aesthetics over actually transit benefits. If the they were concerned about being useful transit the vehicle would have capacity higher than an articulated bus. Instead the main benefit of Trams/LRT over buses, capacity, is sacrificed leaving no real benefits. You can see the same thing with the Obama ere streetcars in the USA where most of them proved no real benefits over the buses the run alongside them but at least they retained the capacity even if it was never needed.
Well the standard response to this kind of "do it the way everyone does it" is "... change has to start somewhere". It's hard to tell, without hearing a report from a council of open-minded-rigorous-experts, whether some claimed innovation on a particular is actually worth doing or not---but certainly neither of "innovation is always good" and "innovation never works" is true.
Anyway everyone is pretty sure that that something is wrong with the standard train economics as you describe them, because if there wasn't something wrong with it there'd be a lot more trains. I can't tell from the site, or from your comment, if this is the solution, or even worth doing as an experiment... but "don't change anything ever" doesn't strike me as productive either.
The problems with trains are well known and they are not addressing them. There might be unknown problems an well, but the things they are talking about have already been tried and failed for reasons they don't seem to be aware of.
Innovation should require some knowlegde of what is already done - otherwise you invent square wheels.
You’re talking about trains, but this is about trams. The design constraints of building into an existing and very dense road network are complex.
I agree with much of your sentiment, and hope that the Coventry council is being challenged in these sorts of ways, but at the same time I recognise that each city is going to have quite different requirements for trams driving down the roads in its centre.
Perhaps a better push back is: why isn’t this just a better bus network?
They operate in completely different scenarios. They’re the same shape, but they’re a different set of hardware, constraints, accessibility, need to be scheduled in a different way to account for traffic, different safety concerns, different signalling systems, different distances, different surroundings.
Again I sorta see what you mean, but feel you’re massively over simplifying this.
You’re grossly oversimplifying and ignoring knock on effects.
Eliminating overhead wires isn’t about cost. It’s about being able to build in existing urban areas that don’t want high voltage live wires everywhere, and likely already have above ground infrastructure they would interfere with.
For me, trams have a much more comfortable ride. The lack of pitch and roll reduces a lot of motion sickness and the rails are obviously a lot smoother than paved surfaces.
There’s nothing stopping a road from being smooth but, logistically, there’s clearly no reason to rush to repair roads when they deteriorate. That means potholes get tolerated, potholes means suspension, and both of those mean bus-like rides instead of suburban light rail rides.
Railway track has to be flat. Anything less than perfect is intolerable so it tends to hold its maintainers to a higher bar.
A bus only lane is also a vehicle lane that is sitting empty a good part of the time.
Not really that efficient...
And, as has been rediscovered about 200 times in Southern California (by the drivers, not by the sstate government), you can add additional lanes almost indefinitely, and it doesn't really help congestion that much.
This is one of these sets of information that don't seem to make sense until you fit it all together.
Busses aren't much more efficient when riding down a lane than lower occupancy vehicles, but streets aren't bottlenecked by their roads, they're bottlenecked by their intersections. The key advantage of a bus is at the intersection. A bus holds the intersection for far less time than the equivalent passenger capacity of cars.
The problem bus lanes try to solve is dominantly that without them the traffic advantage of people riding busses mostly goes to people not riding busses, and this makes for a pretty terrible incentive structure. Busses are intrinsically disadvantaged against cars (schedules, uncertainty, routes), so if you don't help them, then people will prefer to drive. Bus lanes internalize the externality.
No less efficient than track sitting empty most the time.
And your bus only lane has a lot more options. If there is a major disaster you can divert other traffic (not necessarily all traffic though that is an option) into it which might be a useful compromise at time. If you need to repair your bus only lane you just divert the bus to regular traffic. For that matter most places there isn't any traffic and so a bus in mixed traffic has no downsides thus not costing you that whole lane (or track), just build the bus-only lane where it is needed.
Trains are a good thing when they do something a road cannot. However the common bus can be just as good for much less. If you have the money and want good service and ride quality the bus can do it too, and typically for much less cost than a train.
Trains are good where they don't mix with traffic (meaning elevated or underground) because they can then be automated (and also faster). Alternatively a train can hold more people, so if you are in the rare situation where a 100 passenger bus every 5 minutes can't handle the passengers a train is good. Most of the time though you are not in either situation and so a bus can do everything a train can.
> No less efficient than track sitting empty most the time
Unless the track is just in a regular lane that can be full of cars/busses/trucks whenever there isn’t a light train. Like how trams work in most of the world
> A bus only lane is also a vehicle lane that is sitting empty a good part of the time.
A rail track for the same route sits empty just as much.
> you can add additional lanes almost indefinitely, and it doesn't really help congestion that much.
I don't think adding bus-only lanes would have that effect. Adding lanes for private vehicles reduces congestion, which encourages people to move to places along the route until the congestion reaches the previous barely-tolerable level (as I understand it).
I think you've been lied to with that highly misleading statistic. The 3000 for cars is actual (though I'm skeptical of that now too), while the 30,000 for buses is theoretical. "While a typical traffic lane carries approximately 3,000 people in 2,000 cars each hour, the XBL lane can carry over 30,000 people in 700 buses during that same time period." http://fourthplan.org/action/highway-congestion
That doesn't seem unreasonable for the Lincoln tunnel. Rush hour buses are pretty full, 50 on each seems pretty reasonable - everyone got a seat!
> Now the XBL handles 1,850 buses that carry more than 70,000 passengers from 6 a.m. to 10 a.m. each weekday, which comes to 600 buses an hour. The bus lane operates at its maximum capacity for 90 minutes of its four-hour operation.
Here in San Francisco along Mission St we have about 20 articulated buses an hour in each direction. These have a planning capacity of 94, 85% load standard 80, 125% crush capacity 119 according to https://www.reddit.com/r/AskSF/comments/445xdg/what_is_the_m....
While mostly a bus and taxi lane Mission St allows local traffic within each block so buses are still a minority of the vehicles in the lane.
Meanwhile the main 2 lanes in each direction street nearby has 1020 vehicles an hour in the peak direction. At 1.6 people per vehicle that's only about 830 people per lane at rush hour. So even at 'standard capacity' the buses in a regular city street not completely dedicated bus lane carry double the number of people. (From experience I suspect it is somewhat more than that.)
> A bus only lane is also a vehicle lane that is sitting empty a good part of the time.
You can make the same argument (in terms of space) about a train track. The real advantage of trains (light or heavy) is permanence. It's easy for the next government to remove the bus lanes because "OMG too much traffic, one more lane will fix it." It's much more difficult to rip out a rail line and convert it to a road.
Don't measure vehicles per hour. Measure people per hour. Also letting the cars in means more people use cars means you soon need another lane.
Other advantages: people who don't drive, which includes children can get about. Lots of public transport can compensate alot for un walkability of suburbia.
One advantage is that light rail encourages transit oriented development.
The fact that buses are so flexible and easily (and cheaply) rerouted makes developers less likely to build developments that rely on access to transit, but once a community spends a hundreds of millions of dollars on a light rail line, they know it's there for the long term.
That's sort of the popular wisdom, but rails don't guarantee it will be there for the long run. DC recently announced that they're replacing their light rail with buses:
I agree with him that in order to endure and justify a permanent operating subsidy a transit service needs to be useful and used by many people. Most American light rail doesn't meet that bar.
I've seen that claim, but places that run good bus service for decades see plenty of transit oriented development. (most of those places also have subways though. The other options seems to bad bus service which won't get transit oriented development but bad service is enough to explain why)
As a city grows, it's common for the transit system to evolve from direct bus routes to trunk lines supported by local buses. Maybe there was a good bus service to the city center when you bought your home. But now the buses only go to the nearest transit hub, because there is no space for all the buses in the city center anymore. While the average quality of transit may have improved, your services are slower and less convenient than they used to be.
That's sad but I can see that. Maybe more with train and metro stations though than light rail that often makes little difference to commute times vs a bus.
I wouldn't be planning any fixes infrastructure transit programs that didn't have an ROI in the next 7 years. It will be hard for anything to compete with the efficiency of Waymo.
Single passenger cars still have a problem with density even if there's no need for a driver. Combining multiple people into one trip can help, but also lessons the utility of Waymo if riders have to go out of their way to pick up additional passengers.
Getting 1000 people downtown could be up to 2,000 Waymo trips (one trip to drop off the worker, another trip for the car to go back out to pick up another passenger). While one of these 56 passenger very light rail cars can do it in 18 trips. A light rail vehicle like the Siemens trains used in San Francisco can carry up to 200 people at crush loads, so that's 5 trips.
The big AV transit efficiency gains* can only happen when nearly all human drivers are removed from the road. Alas, that's at least 20 years ahead of now**, or more (e.g. if tech stalls for some reason, though I consider it unlikely). Otherwise they'd be limited by having to account for human drivers and that limits speed and throughput enough so other solutions are a must.
* Think having much higher speed limits (as far as humans are concerned, nonexistent), or mass coordinating movement over the entire traffic.
** We can reasonably estimate the minimum without bothering to ask how fast the tech will improve: Even if the tech were available now, think about fleet replacement costs which no one group would be too eager to pay. Best case, it's the typical 'make a concentrated pressure group lose for societal benefit' and we know how that politics goes. It will happen, but slowly.
*** Another thing to account for is that there's no good reason to design an AV car like a normal car, and there'll be some iteration time over that too.
If this were true, cities would have abandoned mass transit for taxi system decades ago. The requirement for there to be a warm body driving a taxi isn't among the prime causes of its inefficiency.
Fair, but how unprofitable should they be? -$5/passenger-mike? -$12/passenger-mile? I think we can do a lot better than the current US mass transit status quo.
In 2022, the NYC Subway budgeted about $0.75 per passenger-mile (and that was during Covid, when ridership was very low) [1]. You’re really overestimating how much public transit costs to run. Private vehicles are an extremely inefficient way to move people around, hence the cost of Uber/Lyft/taxis.
The libertarian answer is yes highways should. Most self proclaimed libertarians refuse to go that far - if you allow for highways to not make money then transit shouldn't be held to the higher bar.
You mean it's very difficult to compete with a company that is massively subsidised by public infrastructure? That's what really killed freight rail in most of Europe, make the train companies pay for track maintance (often the rail companies even want this because it keeps competition out as well), while trucks atpapy very little of the cost they impose on the public (i.e. much higher road usage, causing most of the traffic issues).
This is an estimation for the self-driving hardware cost (computers, LIDAR, sensors). It does not include the base car price, as it can be easily optimized down to almost nothing (sub $10k).
The price is somewhat of a guess, several years ago, the hardware in Waymo was priced at $130k by Munro&Associates. But since then the cost of the LIDAR sensors fell by 90% or so, reducing the main expense.
And Baidu has cars on the road that cost $30k for the _entire_ car. So presumably, so even a couple of pricier sensors won't affect the estimate too much.
> The price is somewhat of a guess, several years ago, the hardware in Waymo was priced at $130k by Munro&Associates
10 years ago they had even more sensors dotting the car, instead of one honeycomb on each corner they had 2. 10 years ago their sensor kit cost double what it does now.
> But since then the cost of the LIDAR sensors fell by 90% or so, reducing the main expense.
I do not know of any lidar that has done that, and Waymo makes their own and we know their price(-ish) (and quantity). I think they’ve actually gone up in price (but also capability - honeycomb 1 vs gen 2).
Are you talking about raw material costs? Or is that one of these extrapolations of if we scale everything to millions of cars and realise no inefficiencies and nobody making any money in the supply chain?
I'm talking about the current cost of the self-driving system, that is already produced by companies that charge a significant markup. With volume, it will go down more.
I'm not including the base vehicle in the cost. It's highly variable, and can be as low as $10k for small personal intra-city taxis.
Why does it blow away any other public transit? That can't be true because if you put the same self driving tech into a bus, you already am an order of magnitude cheaper per passenger (likely more). Moreover let's assume robotaxis are cornering the market and make all other forms of transport non viable. Why would the public then maintain the roads? So at that point at least costs are suddenly going to explode.
Sigh. People are WAAAY too accepting of urbanist propaganda.
Buses are _barely_ more effective than cars. A regular passenger car with 4 people is more efficient than a city bus. An EV needs 2.5 people (these numbers are for the US).
The explanation is simple:
1. Buses have to drive _all_ _the_ _time_, even when there are few passengers. As a result, the average bus load tends to be around 10-20 people. And you can not increase the bus interval to compensate for it because it makes off-rush-hour bus commutes impractical.
2. Buses have INCREDIBLY polluting components: 2-3 drivers for each bus needed to provide the service. They are by far the dirtiest part of the bus. This part can be removed with the self-driving hardware, but...
A full self-driving bus also makes no sense. It defeats the main advantage of self-driving: door-to-door transportation.
That being said, self-driving mini-buses seating 6-10 people are a good idea for rush hour transit.
> Sigh. People are WAAAY too accepting of urbanist propaganda.
>
Sigh people just like to make statements without evidence to back them up.
> Buses are _barely_ more effective than cars. A regular passenger car with 4 people is more efficient than a city bus. An EV needs 2.5 people (these numbers are for the US).
>
Evidence? Moreover you know that average occupancy rates of cars are around 1.5 [1], for short trips like commuting it's more like 1.1 [1] so that's a factor 2 off from your 2.5. So even if we believe your numbers you have to explain how you're going to increase occupancy rate by a factor of 1.5 to 2 before they become just better (not even blowing out of the water).
[1] https://www.eea.europa.eu/publications/ENVISSUENo12/page029....
Note I could not find numbers on buses, but trains in the above source have occupancy rates of 50%.
> The explanation is simple:
>
> 1. Buses have to drive _all_ _the_ _time_, even when there are few passengers. As a result, the average bus load tends to be around 10-20 people. And you can not increase the bus interval to compensate for it because it makes off-rush-hour bus commutes impractical.
>
And robotaxis have to drive empty to and from the person they are picking up.
> 2. Buses have INCREDIBLY polluting components: 2-3 drivers for each bus needed to provide the service. They are by far the dirtiest part of the bus. This part can be removed with the self-driving hardware, but...
>
Not sure how we should account for bus drivers, considering that even if they are not working as bus driver the person is still around (also should we include the emissions from all the engineers working on self driving tech at the moment then) . However your statement is also false in most western countries, at least green house gas emissions of private households are dominated by transport (i.e. Cars).
> A full self-driving bus also makes no sense. It defeats the main advantage of self-driving: door-to-door transportation.
>
You're contradicting yourself. If the bus driver is the most polluting part of the bus (according to your statement above), then it would definitely make sense to get rid of them.
It would be great if your statement was true and robotaxis are the most efficient thing ever. I'd love to see well laid out evidence for this, but from what I just found your statement is not supported by reality.
> The vehicle is battery-powered, eliminating the need for overhead wires. It features an innovative turning system, enabling it to handle 15m radius curves. This allows for installation in tight corners within the existing highway. The Council intends for it to operate at a high frequency, providing a turn-up-and-go service. The vehicle has a capacity of 56, is comfortable and has low floors to enable passengers to embark and disembark easily. The vehicle has been developed to allow autonomous operation in future.
> The new track is laid just 30cm within the road’s surface, minimising the need to relocate pipes and cables, which is time-consuming and expensive. It achieves this by leveraging cutting-edge materials science, while still utilising standard rail parts to ensure ease of manufacture.
It feels like that's putting this into a really awkward place in the tradeoff space. Trams work because they can scale higher than buses. That scale comes at the cost of more up-front infrastructure, much less flexibility, and needing dedicated lanes. So cities don't have trams everywhere, but they're only installed on routes that can support the scale.
For these you still have the up-front investment (just less of it) and inflexibility, but don't get the efficiencies of scale due to how small the capacity is.
Is this really just a bet that they can get autonomous tram-driving on city street approved a decade+ sooner than autonomous buses?
But rather, this is giving up the benefit trams have over buses, without gaining any new edge to replace it. So why is it a good tradeoff? And why now, not 20 years ago?
The autonomous driving angle is the only idea I have.
I haven’t found the projected figures for Coventry but it would be very, very awkward if they can’t beat the numbers above with a supposedly much cheaper track.
https://en.wikipedia.org/wiki/Trams_in_Besan%C3%A7on?wprov=s...
They make all kinds of claims that don't stand up to over 100 years of history running trains. The claim they are innovative, but there is nothing new here, and no evidence they have looked at the real problems of transit systems. Someone is going to make a lot of money on this at the expense of the community that loses.
Trains have been around for a long time. You can buy all the parts you need for a good system off the shelf. You won't be saving money by designing something new, you just waste money on engineers to design something and then lose the scale factors you could get from buying the same thing as everyone else. If you buy the same thing as everyone else that means there will be a market for spare parts and thus in 20 years when (not if!) something breaks you can keep the system running.
Yes overhead wires are expensive - but they are a rounding error compared to track. Batteries are expensive too, and you have to buy a lot of them. Batteries need to be recharged which means these trams will be out of service often so they have to buy a lot more so that when one is out of service for charging the others can work. (you still need a few extra for maintenance, but battery charging is more common so you need a lot more)
If you want to build a train the best way to save money is to build exactly the same as everyone else does: standard off the shelf trains, running on standard off the shelf rails, and standard off the shelf overhead rail. If you want to innovate make sure that everyone is fluent in Spanish, Turkish, Korean, or Italian - because places where those languages are spoke build and run trains much cheaper than other places you can think of so you want to learn from them. (note that French or Japanese are not on the above list - while those areas do cheaper than English speakers, they are still expensive)
I'm not sure about the UK, but in the US most of the cost blowout for trains seems to be in stations, so focus all your innovation there: don't make them monuments to how much money you can spend. (The UK has cost problems almost as bad as the US, but I'm not aware of any study on where the issues come from, while at least in the US there are studies).
Anyway everyone is pretty sure that that something is wrong with the standard train economics as you describe them, because if there wasn't something wrong with it there'd be a lot more trains. I can't tell from the site, or from your comment, if this is the solution, or even worth doing as an experiment... but "don't change anything ever" doesn't strike me as productive either.
Innovation should require some knowlegde of what is already done - otherwise you invent square wheels.
I agree with much of your sentiment, and hope that the Coventry council is being challenged in these sorts of ways, but at the same time I recognise that each city is going to have quite different requirements for trams driving down the roads in its centre.
Perhaps a better push back is: why isn’t this just a better bus network?
There are different modes of operation that differentiate them but fundamentaly they are all trains and face the same issues
Again I sorta see what you mean, but feel you’re massively over simplifying this.
Eliminating overhead wires isn’t about cost. It’s about being able to build in existing urban areas that don’t want high voltage live wires everywhere, and likely already have above ground infrastructure they would interfere with.
There’s nothing stopping a road from being smooth but, logistically, there’s clearly no reason to rush to repair roads when they deteriorate. That means potholes get tolerated, potholes means suspension, and both of those mean bus-like rides instead of suburban light rail rides.
Railway track has to be flat. Anything less than perfect is intolerable so it tends to hold its maintainers to a higher bar.
Modern urban light rail is also typically electric, using overhead power. Although buses can also use this.
This is one of the main reasons the super dense Japanese cities aren't as air poluted as other urban centers.
Not really that efficient...
And, as has been rediscovered about 200 times in Southern California (by the drivers, not by the sstate government), you can add additional lanes almost indefinitely, and it doesn't really help congestion that much.
Busses aren't much more efficient when riding down a lane than lower occupancy vehicles, but streets aren't bottlenecked by their roads, they're bottlenecked by their intersections. The key advantage of a bus is at the intersection. A bus holds the intersection for far less time than the equivalent passenger capacity of cars.
The problem bus lanes try to solve is dominantly that without them the traffic advantage of people riding busses mostly goes to people not riding busses, and this makes for a pretty terrible incentive structure. Busses are intrinsically disadvantaged against cars (schedules, uncertainty, routes), so if you don't help them, then people will prefer to drive. Bus lanes internalize the externality.
And your bus only lane has a lot more options. If there is a major disaster you can divert other traffic (not necessarily all traffic though that is an option) into it which might be a useful compromise at time. If you need to repair your bus only lane you just divert the bus to regular traffic. For that matter most places there isn't any traffic and so a bus in mixed traffic has no downsides thus not costing you that whole lane (or track), just build the bus-only lane where it is needed.
Trains are a good thing when they do something a road cannot. However the common bus can be just as good for much less. If you have the money and want good service and ride quality the bus can do it too, and typically for much less cost than a train.
Trains are good where they don't mix with traffic (meaning elevated or underground) because they can then be automated (and also faster). Alternatively a train can hold more people, so if you are in the rare situation where a 100 passenger bus every 5 minutes can't handle the passengers a train is good. Most of the time though you are not in either situation and so a bus can do everything a train can.
Unless the track is just in a regular lane that can be full of cars/busses/trucks whenever there isn’t a light train. Like how trams work in most of the world
A rail track for the same route sits empty just as much.
> you can add additional lanes almost indefinitely, and it doesn't really help congestion that much.
I don't think adding bus-only lanes would have that effect. Adding lanes for private vehicles reduces congestion, which encourages people to move to places along the route until the congestion reaches the previous barely-tolerable level (as I understand it).
While that bus lane may look empty most of the time it likely carries far more people per hour than the congested car lane next to it.
> While the Lincoln Tunnel’s car lane can only move 3,000 people per hour in each car lane, its bus lane moves 30,000 people per hour.
https://transalt.org/blog/bus-commutes-are-significantly-lon...
> Now the XBL handles 1,850 buses that carry more than 70,000 passengers from 6 a.m. to 10 a.m. each weekday, which comes to 600 buses an hour. The bus lane operates at its maximum capacity for 90 minutes of its four-hour operation.
https://www.govtech.com/transportation/fed-funds-study-of-ai...
Here in San Francisco along Mission St we have about 20 articulated buses an hour in each direction. These have a planning capacity of 94, 85% load standard 80, 125% crush capacity 119 according to https://www.reddit.com/r/AskSF/comments/445xdg/what_is_the_m....
While mostly a bus and taxi lane Mission St allows local traffic within each block so buses are still a minority of the vehicles in the lane.
Meanwhile the main 2 lanes in each direction street nearby has 1020 vehicles an hour in the peak direction. At 1.6 people per vehicle that's only about 830 people per lane at rush hour. So even at 'standard capacity' the buses in a regular city street not completely dedicated bus lane carry double the number of people. (From experience I suspect it is somewhat more than that.)
You can make the same argument (in terms of space) about a train track. The real advantage of trains (light or heavy) is permanence. It's easy for the next government to remove the bus lanes because "OMG too much traffic, one more lane will fix it." It's much more difficult to rip out a rail line and convert it to a road.
Other advantages: people who don't drive, which includes children can get about. Lots of public transport can compensate alot for un walkability of suburbia.
The fact that buses are so flexible and easily (and cheaply) rerouted makes developers less likely to build developments that rely on access to transit, but once a community spends a hundreds of millions of dollars on a light rail line, they know it's there for the long term.
https://www.washingtonpost.com/dc-md-va/2025/05/27/steetcar-...
Jarrett Walker has a good piece about it: https://humantransit.org/2025/05/what-was-wrong-with-the-was...
I agree with him that in order to endure and justify a permanent operating subsidy a transit service needs to be useful and used by many people. Most American light rail doesn't meet that bar.
Getting 1000 people downtown could be up to 2,000 Waymo trips (one trip to drop off the worker, another trip for the car to go back out to pick up another passenger). While one of these 56 passenger very light rail cars can do it in 18 trips. A light rail vehicle like the Siemens trains used in San Francisco can carry up to 200 people at crush loads, so that's 5 trips.
* Think having much higher speed limits (as far as humans are concerned, nonexistent), or mass coordinating movement over the entire traffic.
** We can reasonably estimate the minimum without bothering to ask how fast the tech will improve: Even if the tech were available now, think about fleet replacement costs which no one group would be too eager to pay. Best case, it's the typical 'make a concentrated pressure group lose for societal benefit' and we know how that politics goes. It will happen, but slowly.
*** Another thing to account for is that there's no good reason to design an AV car like a normal car, and there'll be some iteration time over that too.
[1]: https://data.transportation.gov/Public-Transit/2022-2023-NTD...
I don’t think fixed route transport infrastructure is going to have trouble competing on efficiency.
They were targeting $7.5k for their in house honeycomb lidars and they have 12 of them - that’s 90k already.
https://www.theverge.com/2021/8/27/22644370/waymo-lidar-stop...
They also aren’t close to the $7.5k target (there isn’t any public source for that so you’ll have to take my word for it).
Also $30k wouldn’t even cover the base vehicle.
The price is somewhat of a guess, several years ago, the hardware in Waymo was priced at $130k by Munro&Associates. But since then the cost of the LIDAR sensors fell by 90% or so, reducing the main expense.
And Baidu has cars on the road that cost $30k for the _entire_ car. So presumably, so even a couple of pricier sensors won't affect the estimate too much.
> The price is somewhat of a guess, several years ago, the hardware in Waymo was priced at $130k by Munro&Associates
10 years ago they had even more sensors dotting the car, instead of one honeycomb on each corner they had 2. 10 years ago their sensor kit cost double what it does now.
> But since then the cost of the LIDAR sensors fell by 90% or so, reducing the main expense.
I do not know of any lidar that has done that, and Waymo makes their own and we know their price(-ish) (and quantity). I think they’ve actually gone up in price (but also capability - honeycomb 1 vs gen 2).
Waymo uses brand-new electric Jaguars.
But there is no _reason_ to use Jaguars and not specially-built smaller and less powerful cars, when Waymo finally starts a real rollout.
I'm not including the base vehicle in the cost. It's highly variable, and can be as low as $10k for small personal intra-city taxis.
China has already launched a $30k taxi: https://www.forbes.com/sites/bradtempleton/2024/05/14/baidu-...
This _completely_ blows any transit out of the competition. Literally nothing can come even close in the end-to-end efficiency.
Buses are _barely_ more effective than cars. A regular passenger car with 4 people is more efficient than a city bus. An EV needs 2.5 people (these numbers are for the US).
The explanation is simple:
1. Buses have to drive _all_ _the_ _time_, even when there are few passengers. As a result, the average bus load tends to be around 10-20 people. And you can not increase the bus interval to compensate for it because it makes off-rush-hour bus commutes impractical.
2. Buses have INCREDIBLY polluting components: 2-3 drivers for each bus needed to provide the service. They are by far the dirtiest part of the bus. This part can be removed with the self-driving hardware, but...
A full self-driving bus also makes no sense. It defeats the main advantage of self-driving: door-to-door transportation.
That being said, self-driving mini-buses seating 6-10 people are a good idea for rush hour transit.
Sigh people just like to make statements without evidence to back them up.
> Buses are _barely_ more effective than cars. A regular passenger car with 4 people is more efficient than a city bus. An EV needs 2.5 people (these numbers are for the US). >
Evidence? Moreover you know that average occupancy rates of cars are around 1.5 [1], for short trips like commuting it's more like 1.1 [1] so that's a factor 2 off from your 2.5. So even if we believe your numbers you have to explain how you're going to increase occupancy rate by a factor of 1.5 to 2 before they become just better (not even blowing out of the water). [1] https://www.eea.europa.eu/publications/ENVISSUENo12/page029....
Note I could not find numbers on buses, but trains in the above source have occupancy rates of 50%.
> The explanation is simple: > > 1. Buses have to drive _all_ _the_ _time_, even when there are few passengers. As a result, the average bus load tends to be around 10-20 people. And you can not increase the bus interval to compensate for it because it makes off-rush-hour bus commutes impractical. >
And robotaxis have to drive empty to and from the person they are picking up.
> 2. Buses have INCREDIBLY polluting components: 2-3 drivers for each bus needed to provide the service. They are by far the dirtiest part of the bus. This part can be removed with the self-driving hardware, but... >
Not sure how we should account for bus drivers, considering that even if they are not working as bus driver the person is still around (also should we include the emissions from all the engineers working on self driving tech at the moment then) . However your statement is also false in most western countries, at least green house gas emissions of private households are dominated by transport (i.e. Cars).
> A full self-driving bus also makes no sense. It defeats the main advantage of self-driving: door-to-door transportation. >
You're contradicting yourself. If the bus driver is the most polluting part of the bus (according to your statement above), then it would definitely make sense to get rid of them.
It would be great if your statement was true and robotaxis are the most efficient thing ever. I'd love to see well laid out evidence for this, but from what I just found your statement is not supported by reality.