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On average buses get slightly WORSE fuel efficiency in MPG than the average car.
This is because individual buses are larger and burn more fuel. To get better fuel efficiency they need higher load factors - more passengers on board. On average cars get more than 1 - about 1.5 in the USA, I think. Buses to breakeven (on average) need over ten, and on average they get about 9.
BUT - that does not mean that having fewer people ride buses would result in saving fuel. Why?
1. The incremental fuel per passenger is infitesmal. Switch 25% of your riders to cars, and you will get a lot more car trips. But you won't get fewer buses rolling on those low ridership lines, because you need a minimum frequency to make it useable at all (the high ridership crowded lines of course are MORE fuel efficient than cars). To realize the savings, you would have to eliminate the lines. But the lowest ridership lines tend to be in low density areas (sometimes semi-rural) where the only riders are doing so because they have no alternative - they either cannot afford any car, they are too disabled, too young, too old, can't drive to legal issues, or otherwise cannot use a car. buses are provided to them effectively as a social service. Eliminating the buses would not all of a sudden shift them to cars at 1.5 passengers per vehicle but would burden social service agencies with transport needs (that would be met inefficiently) or it would simply eliminate mobility for these people.
2. If the bus passengers switched to cars at 1 person per vehicle (quite likely, since those with ridesharing options are often already not going to be on the bus) then they would increase fuel usage even at average bus loads
3. Provision of transit can make it possible for people at the margin to live car free - which means not just a shift of car trips to (in some cases) less efficient bus trips - but shift of car trips to zero fuel using walking trips.
4. Similarly, transit user may well take shorter trips than auto users, so even if its less efficient per mile, autos would still require more fuel.
5. The provision of transit, and less need for parking, can result in destinations being more densely built, which can make possible more walking even among those who are not car free, and do not use the bus.
IF we are truely concerned about bus fuel inefficiency - rather than fantasize about local govts abandoning the poor, old, handicapped, and legally challenged to immobility (though that WOULD increase average bus MPG by eliminating the lowest ridership lines) - there are other things we can do.
A. Reduce bus fares on existing lines, to increase utilization.
B. Consolidate stops and eliminate non direct routes, to increase efficiency'
C. Use appropriate sized buses for the route - run small minibuses on less heavily utilized routes
D. To improve the economics of keeping a seperate fleet of such small minibuses, use lower paid, nonunion if necessary, drivers
E. Move even small steps in the direction of BRT - eg bus priority at intersections, not only to increase ridership (thereyby improving load factors) but to improve fuel efficiency by reducing bus idling.
F. Clarify bus maps, station markings, etc to make buses more user friendly, and thus increase ridership.
note if autos had one person per vehicle, buses on average would be more efficient than cars even now, even with all the inefficiencies of current bus ops.
If the people you switch from buses to cars by eliminating bus routes, or reducing service on them, or increasing fares on them, are mostly people traveling alone, you will increase fuel consumption. Period, without taking into account the other transit benefits mentioned above.
You have to decide on your conditions before you make your measurement. If you don't get the answer you like, adding in a bunch of stuff is just putting your thumb on your scale. After all, I could add in a bunch of stuff (perhaps much of it dubious) on the car side.
Hypothetically, buses are more efficient. All we need to do is get more people riding buses.
Reality, cars are more efficient. In reality, more passengers are added to buses either by making driving prohibitively expensive (such as with parking downtown) or by making bus service better. Making bus service better means running more buses more frequently. What that has overwhelmingly done throughout history is lower the number of passengers per bus. Instead of having an average load of 800 passengers for an average of 100 buses in operation at any given time, you get 1500 passengers on 200 buses. Double the buses, not double the passengers. I'm making up numbers here as I don't have the actual numbers on hand. Conversely, the opposite is also generally true. During the budget crisis, many jurisdictions were forced to cut transit service and reduce the number of buses. While ridership decreased, it decreased less than the reduction in service.
This is called sensitivity analysis. It's straight forward analysis that any business major (and they're not rock scientists) learns. Simply put, there's overwhelming empirical evidence that the coefficient of correlation of bus passengers to bus service is less than 1. That means increasing buses will never be a solution to make buses more efficient than cars. It's just a flat out statistical impossibility. To make buses more efficient than cars requires other approaches. Parking can be made too expensive thus increasing ridership without adding buses to improve service. Congestion charges can be levied. Infrastructure bottlenecks can be imposed such as taking away a vehicle lane and converting it to bus-only. In a nut shell: Punitive measures against drivers work to make buses more efficient. Increasing the quantity of bus service works to make buses less efficient. Increasing quality of bus service (lane prioritization, bus only lanes, better designed bus stops where the bus doesn't get stuck every 400 feet by traffic) work quite well, although generally at the expense of being punitive to drivers. That might make sense in San Francisco or NYC, but doesn't really make sense here where fewer than 1% of trips are made by transit.
Parking can be made too expensive thus increasing ridership without adding buses to improve service. Congestion charges can be levied. Infrastructure bottlenecks can be imposed such as taking away a vehicle lane and converting it to bus-only. In a nut shell: Punitive measures against drivers work to make buses more efficient.
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And some of these punitive measures don't work anyway, which you don't always find out until you implement them. I'm thinking of Minervah's posts about building apartments without parking in Portland.
Aside from punitive measures, minimal expansion of road networks compared to population growth can make driving worse (more congestion) and lead to higher transit use with little service improvements, especially if it causes people to change where they live. Rising gas prices too.
I still wonder what the efficiency of buses in larger cities is though. And while you could increase fuel efficiency by using smaller buses on low ridership routes, people could also use more fuel efficient cars...
If a fairly average 5000 lb car caries 1.5 people, that's 3300 lbs per person. Assuming fuel use is directly tied to mass (feel free to comment on that), that means a 27,000 lb bus would have to have only 8 people on average to do as well as a car. Are there other things going on that would make a bus consume significantly more energy (ie not just 10-20%), or is the average bus just that under-utilized?
^^I think most cities have some minimal requirements for roads, especially for reasons of public safety.
You young guys think moving is a lark and that people move frequently, like you do. Most adults like to stay put, especially once there is a family involved, which necessitates changing schools, etc.
^^I think most cities have some minimal requirements for roads, especially for reasons of public safety.
That is true, but I don't see how that would affect the amount of lanes or highways built. For example, Vancouver not building highways through the city is probably partly responsible for it's high transit use, though even without highways it's probably more pleasant to drive in and park in that say, Boston.
It got a big boost in transit ridership with the construction of Skytrain (Rapid Transit in the sense it's all grade separated). So a combination of disincentive and incentives, it got high transit ridership.
I still wonder what the efficiency of buses in larger cities is though. And while you could increase fuel efficiency by using smaller buses on low ridership routes, people could also use more fuel efficient cars...
I posted a link earlier. I'll search for it later today.
Quote:
If a fairly average 5000 lb car caries 1.5 people, that's 3300 lbs per person. Assuming fuel use is directly tied to mass (feel free to comment on that), that means a 27,000 lb bus would have to have only 8 people on average to do as well as a car. Are there other things going on that would make a bus consume significantly more energy (ie not just 10-20%), or is the average bus just that under-utilized?
5000 lbs is heavy for car except for maybe some large SUVs. 3500, 3000 for compact cars is more reasonable. Fuel use isn't just tied to mass, it's more complicated that that, but obviously it's a big part. Engine efficiency and engine size makes a big difference, the same 3500 lb car today gets more fuel efficiency than it would years ago. Local buses that start and stop a lot use up more fuel. Many buses are old vehicles and bought for their cheapness rather than low fuel use. Buses tend to compete for cars where people would be driving alone (such as commuting), 1.3 maybe less per car might be a better comparison.
A lot of American buses do get low ridership, but another factor is one that appears to get high ridership to riders might be less than it seems. Many routes have one direction that gets more riders than the other. A bus that's well used one direction and then nearly empty the other will have its efficiency dragged down. Or, a bus might fill up near one end of the route (or in the middle) but at one or both ends would be running nearly empty.
That is true, but I don't see how that would affect the amount of lanes or highways built. For example, Vancouver not building highways through the city is probably partly responsible for it's high transit use, though even without highways it's probably more pleasant to drive in and park in that say, Boston.
It got a big boost in transit ridership with the construction of Skytrain (Rapid Transit in the sense it's all grade separated). So a combination of disincentive and incentives, it got high transit ridership.
It could affect the number of lanes for a road servicing a large development.
DH used to go to Vancouver frequently on business (happily, they just closed the Vancouver office) and he was not impressed. Just sayin'.
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