4 ms·

I recall reading an article a few years ago about Bogotá's transit, where the mayor (I think) said something very interesting. Among other arguments, he made a

I recall reading an article a few years ago about Bogotá's transit, where the mayor (I think) said something very interesting. Among other arguments, he made a moral argument about the dedicated lane for transit. Roughly, there's 40 or 50 people on the bus, vs 1-2 per car, and you get, what, 3? 2? cars in the space of a bus. He found it completely unjustified to let the convenience of those 45 people be outweighed by the convenience of the 4 or 5. I'm not sure that it stacks up perfectly logically, but it's an interesting way to think about it. And it looks like they have a pretty good system.

nordsieck 8y ago
> Roughly, there's 40 or 50 people on the bus, vs 1-2 per car, and you get, what, 3? 2? cars in the space of a bus. He found it completely unjustified to let the convenience of those 45 people be outweighed by the convenience of the 4 or 5. That's only true if the lane is as full of busses as other lanes are full of cars.
- cozzyd 8y ago
  Yes, but if the bus is faster, more people will take the bus and so you will add more buses. In places like Quito with dedicated busways, there are buses basically non-stop. Buses can follow one another better than trains too because you don't have the signal system reducing headways.
  - nordsieck 8y ago
    For the record I'm a huge fan of busses and highly skeptical of trains. I'm sure that there are some places in the world where the Mayor's statement is true. Those places are rare. In a downtown corridor during rush hour? Sure - I could totally see a lane full of just busses. However, most dedicated bus lanes won't be that busy. This isn't to say that there aren't good reasons for dedicated lanes - just that the reason the Mayor gave was at best hyperbolic and at worst maliciously deceptive. > more people will take the bus and so you will add more buses. In a well run business that would be true. In the first world, most busses are heavily subsidized. This means that the more busses that are run, the more money the system loses (not strictly true, but roughly). What you say should make sense, but it doesn't for important institutional reasons.
    - apendleton 8y ago
      > In the first world, most busses are heavily subsidized. This means that the more busses that are run, the more money the system loses (not strictly true, but roughly). So what? Transportation infrastructure for single-passenger vehicles is also subsidized in the US (the gas tax doesn't come anywhere near paying for roads, for instance), and it gets more expensive with more users too (in the form of increased wear on roads requiring more maintenance, or the need to expand roads to accommodate increasing use). But we do it anyway, because transportation infrastructure is a public good. I've never understood the inclination that public transit should stand alone among transportation modes and operate without subsidy.
    - so33 8y ago
      >In a downtown corridor during rush hour? Sure - I could totally see a lane full of just busses. However, most dedicated bus lanes won't be that busy. These are precisely the places where dedicated bus lanes and BRTs exist. BRT is called bus rapid transit because there is a planned frequency for these buses - therefore a need for consistent, uninterrupted rights of way. >In a well run business that would be true. In the first world, most busses are heavily subsidized. Only because highly popular bus routes (and train routes) subsidize unpopular routes that exist for the public good and not to make money - neighborhood routes, night buses, etc. In the US, routes are highly subsidized because of a lack of density compared to Europe or Asia.
    - icc97 8y ago
      > I'm sure that there are some places in the world where the Mayor's statement is true. In Europe this is predominantly true (maybe not the UK outside London). There's still massive traffic jam problems but buses certainly during rush hour are full and special lanes are provided for them.
    - emj 8y ago
      > In the first world, most busses are heavily subsidized. Public transport makes it possible for more people to use the roads it makes it faster for people that have to go by car. So what you call subsidized is actually a way to activate capital sunk into expensive infrastructure and make it more effective.
- labcomputer 8y ago
  > That's only true if the lane is as full of busses as other lanes are full of cars. 1) The density of people per unit road area is about 10 times greater than with cars. A bus lane only needs to carry 1/10th as many buses to come out ahead (and a bus occupies considerably less space than 10 cars). 2) The relevant metric isn't people (or vehicles) per unit road area. It's the lane's flux of people per unit time. On that metric, an free flowing carpool lane will beat a congested regular lane every time (even when the carpool lane appears empty to the layman). You can do your own back of the napkin calculation, but vehicles have to packed roughly 5 to 10 times denser in the congested lane to achieve the same vehicle flux per unit time. That means a free flowing carpool lane (>=2 people) only needs about 1/20th the vehicle density per unit area to come out ahead of a congested single-occupancy lane. It's just no contest with an uncongested bus lane: Buses will win on a people per time metric with only 1% as many vehicles per unit area. To visualize this, 100 closely packed cars (remember, they are not touching!) is about three city blocks long.
Zanni 8y ago
I've seen this same argument about buses only taking up the amount of space as a handful of cars, but I think it's based on an incorrect assumption. Namely, it's only true in a static picture. If you look at the dynamic picture, cars and buses in motion, then buses take up a lot more "room." They're slow to accelerate. They stop frequently. They block traffic when they stop. They're huge, and people can't get around them as easily as they can around cars. They impede traffic in all sorts of ways that cars don't. Buses might still have an advantage, but I don't think it's as large as is claimed. (Separate peeve: it's always assumed that buses are nearly full and cars are nearly empty.)
- emj 8y ago
  What you bring up stems from two things, infrastructure needs to prioritize busses, and second comparing busses to single car does not work. Since we are obviously talking about rush hour. At a traffic light in a busy intersection where I live there will be max 15 people in cars, 50-400 people in busses, and about 100 more on the streets walking and bicycling. I think 5 times more people in busses is a pretty good advantage.
  - Zanni 8y ago
    I don't disagree (infrastructure should prioritize, or at least accommodate) buses when they're used. But it currently does not. Also, your example seems to be from a dense, urban center, but of course not everyone on those buses started in the city; a lot of them had to get there from somewhere else, and there the advantage is less pronounced the case for dedicated infrastructure harder to make.
- wool_gather 8y ago
  These all sound like more reasons to put buses and cars into separate paths.
  - Zanni 8y ago
    I would love to see separate lanes for buses and cars. In Hawaii, where I live, there was a proposal for an elevated, bus-only, viaduct that ran the length of a major freeway. This would have enabled buses that run as frequently as trains and are unimpeded by rush hour traffic, and are cheaply and easily scalable with demand. Instead we're getting an elevated train that has disrupted traffic already with its construction, that has blown through its budget with no end in sight, will be stopping short of its original end point due to cost overruns, and is only expected to reduce parallel car traffic by 2%. Ugh.

nordsieck 8y ago

> Roughly, there's 40 or 50 people on the bus, vs 1-2 per car, and you get, what, 3? 2? cars in the space of a bus. He found it completely unjustified to let the convenience of those 45 people be outweighed by the convenience of the 4 or 5. That's only true if the lane is as full of busses as other lanes are full of cars.

cozzyd 8y ago
Yes, but if the bus is faster, more people will take the bus and so you will add more buses. In places like Quito with dedicated busways, there are buses basically non-stop. Buses can follow one another better than trains too because you don't have the signal system reducing headways.
- nordsieck 8y ago
  For the record I'm a huge fan of busses and highly skeptical of trains. I'm sure that there are some places in the world where the Mayor's statement is true. Those places are rare. In a downtown corridor during rush hour? Sure - I could totally see a lane full of just busses. However, most dedicated bus lanes won't be that busy. This isn't to say that there aren't good reasons for dedicated lanes - just that the reason the Mayor gave was at best hyperbolic and at worst maliciously deceptive. > more people will take the bus and so you will add more buses. In a well run business that would be true. In the first world, most busses are heavily subsidized. This means that the more busses that are run, the more money the system loses (not strictly true, but roughly). What you say should make sense, but it doesn't for important institutional reasons.
  - apendleton 8y ago
    > In the first world, most busses are heavily subsidized. This means that the more busses that are run, the more money the system loses (not strictly true, but roughly). So what? Transportation infrastructure for single-passenger vehicles is also subsidized in the US (the gas tax doesn't come anywhere near paying for roads, for instance), and it gets more expensive with more users too (in the form of increased wear on roads requiring more maintenance, or the need to expand roads to accommodate increasing use). But we do it anyway, because transportation infrastructure is a public good. I've never understood the inclination that public transit should stand alone among transportation modes and operate without subsidy.
  - so33 8y ago
    >In a downtown corridor during rush hour? Sure - I could totally see a lane full of just busses. However, most dedicated bus lanes won't be that busy. These are precisely the places where dedicated bus lanes and BRTs exist. BRT is called bus rapid transit because there is a planned frequency for these buses - therefore a need for consistent, uninterrupted rights of way. >In a well run business that would be true. In the first world, most busses are heavily subsidized. Only because highly popular bus routes (and train routes) subsidize unpopular routes that exist for the public good and not to make money - neighborhood routes, night buses, etc. In the US, routes are highly subsidized because of a lack of density compared to Europe or Asia.
  - icc97 8y ago
    > I'm sure that there are some places in the world where the Mayor's statement is true. In Europe this is predominantly true (maybe not the UK outside London). There's still massive traffic jam problems but buses certainly during rush hour are full and special lanes are provided for them.
  - emj 8y ago
    > In the first world, most busses are heavily subsidized. Public transport makes it possible for more people to use the roads it makes it faster for people that have to go by car. So what you call subsidized is actually a way to activate capital sunk into expensive infrastructure and make it more effective.
labcomputer 8y ago
> That's only true if the lane is as full of busses as other lanes are full of cars. 1) The density of people per unit road area is about 10 times greater than with cars. A bus lane only needs to carry 1/10th as many buses to come out ahead (and a bus occupies considerably less space than 10 cars). 2) The relevant metric isn't people (or vehicles) per unit road area. It's the lane's flux of people per unit time. On that metric, an free flowing carpool lane will beat a congested regular lane every time (even when the carpool lane appears empty to the layman). You can do your own back of the napkin calculation, but vehicles have to packed roughly 5 to 10 times denser in the congested lane to achieve the same vehicle flux per unit time. That means a free flowing carpool lane (>=2 people) only needs about 1/20th the vehicle density per unit area to come out ahead of a congested single-occupancy lane. It's just no contest with an uncongested bus lane: Buses will win on a people per time metric with only 1% as many vehicles per unit area. To visualize this, 100 closely packed cars (remember, they are not touching!) is about three city blocks long.

Zanni 8y ago

I've seen this same argument about buses only taking up the amount of space as a handful of cars, but I think it's based on an incorrect assumption. Namely, it's only true in a static picture. If you look at the dynamic picture, cars and buses in motion, then buses take up a lot more "room." They're slow to accelerate. They stop frequently. They block traffic when they stop. They're huge, and people can't get around them as easily as they can around cars. They impede traffic in all sorts of ways that cars don't. Buses might still have an advantage, but I don't think it's as large as is claimed. (Separate peeve: it's always assumed that buses are nearly full and cars are nearly empty.)

emj 8y ago
What you bring up stems from two things, infrastructure needs to prioritize busses, and second comparing busses to single car does not work. Since we are obviously talking about rush hour. At a traffic light in a busy intersection where I live there will be max 15 people in cars, 50-400 people in busses, and about 100 more on the streets walking and bicycling. I think 5 times more people in busses is a pretty good advantage.
- Zanni 8y ago
  I don't disagree (infrastructure should prioritize, or at least accommodate) buses when they're used. But it currently does not. Also, your example seems to be from a dense, urban center, but of course not everyone on those buses started in the city; a lot of them had to get there from somewhere else, and there the advantage is less pronounced the case for dedicated infrastructure harder to make.
wool_gather 8y ago
These all sound like more reasons to put buses and cars into separate paths.
- Zanni 8y ago
  I would love to see separate lanes for buses and cars. In Hawaii, where I live, there was a proposal for an elevated, bus-only, viaduct that ran the length of a major freeway. This would have enabled buses that run as frequently as trains and are unimpeded by rush hour traffic, and are cheaply and easily scalable with demand. Instead we're getting an elevated train that has disrupted traffic already with its construction, that has blown through its budget with no end in sight, will be stopping short of its original end point due to cost overruns, and is only expected to reduce parallel car traffic by 2%. Ugh.