Tuesday, October 30, 2007

Addendum on bus efficiency

To follow on on how full a bus (or light rail car) must be to achieve parity with the passenger automobile, consider that for the most part, transit goes inbound in the morning and outbound in the evening, and is hardly used at all between rush hours. In other words, only one fourth of buses or light rail cars have significant ridership, and thus each bus going the ordinary direction during rush hour needs about 40 to 60 riders to merely "break even" in terms of energy usage. A light rail car would need about 100 passengers to "break even" in terms of energy usage and carbon emissions.

An average bus carries 40 passengers, and a typical light rail car might carry 66. The very structure of centralized transit shows that it can never be an environmental benefit when compared with the ordinary automobile.

9 comments:

pentamom said...

Hmmmm....just wondering....is there an environmental benefit, and if so, how would you measure it, to the reduction in traffic congestion provided by mass transit?

IOW, if there are significantly fewer cars, there will be fewer traffic jams, or jams of shorter duration, or whatever. Fewer jams means that the cars that are out there are maximizing their miles per gallon efficiency, since they're not sitting idle through several light changes.

It's probably not significant enough to make up the difference, and would be fairly hard to quantify, but I imagine there's some positive effect from it, at least.

Bike Bubba said...

There might be. On the other hand, you've got the issues of transportation funds pilfered for buses instead of being used for more lanes, and traffic backing up behind a bus stopped to pick up passengers.

Somehow I bet that if you accounted for both sides of the equation, transit STILL loses out in a big way, environmentally speaking.

pentamom said...

Oh, probably. But "more lanes" isn't always a good, or even possible, solution.

Bike Bubba said...

Yeah, but keep in mind that you can put two cars in the space filled by a bus, and that's not that far from replacing the riders on that bus. :^)

Seriously, only 3-5% of commuters use transit here in the Twin Cities. You could do a lot of good by simply repairing roads better, and thus getting rid of a lot of the construction backups.

Terry Lange said...

The Twin Cities is a bad place to make judgments about mass transit because it is overfunded and under used.

Look at cities like Washington DC or London, England.

Bike Bubba said...

Actually, Terry, cities designed around transit are even worse. The trick is that a fair number of people in Minneapolis commute to the suburbs to work. However, you don't find too many people commuting from the Loop to Schaumburg in Chicago, or from Manhattan to Chatauqua.

Hence, the outbound buses/trains in a city "designed for transit" will be even emptier than those here--meaning that the passenger load for the inbound buses/trains must be even greater in a city designed for transit.

And those subsidies? Sorry, they're just as massive in Chicago, New York City, and London as they are here or in LA. It's simply not efficient to run buses and trains in such a way as to guarantee that they'll be 75% empty.

Or worse.

Terry Lange said...

My point was that places like DC and London are so car congested and expensive to park in, that transit makes sense. I have been to DC several times and I have found that the Metro is the best way to get around, it is cheap, safe and it beats trying to find a parking place.

With London, if you drive into the city, you have to pay a Congestion charge. Also, parking is almost impossible and again very expensive. Why not take the London Underground "the tube" and it will take you all over the city and much cheaper, less hassle.

Bike Bubba said...

True; where a city's been designed around transit, it becomes difficult to impossible to use more efficient means of transportation. However, that just means that they prevented the best system from being used; it certainly doesn't mean that the system they chose is efficient.

Two appalling examples of this are the District of Columbia and Manhattan. DC somehow took L'Enfant's broad boulevards and made them impassible for vehicle traffic--that's an urban planning legacy worth of Amtrak, the DMV, or the Post Office. If they took over the Sahara, they'd somehow manage to have a shortage of sand within five years, I think.

In the same way, much of the gridlock in lower Manhattan was due to the removal of five significant streets to build the ill-fated World Trade Center.

jroosh said...

another benefit...

a bus or light rail car never looks cool...

My car looks cool whether it's moving or parked!