Comment by johnea
1 day ago
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.
I live in a city with trams in the UK and that’s not how it works. There are sections that run on dedicated train lines, and sections where it runs on the street. Where it runs on the streets, priority is given over cars by switching traffic lights to red. Once the tram has passed onto the road it switches back to green so you can end up following the tram in your car.
> 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).
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.
> A bus only lane is also a vehicle lane that is sitting empty a good part of the time.
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...
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.
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.)
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> 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.