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April 15, 2005

Bus Rapid Transit

In the great Seattle transit wars (light rail--monorail--buses), I have no ideological attachment to any particular technology. I'm interested in real quantitative analysis of long-term benefits per dollar spent. So, in today's two long articles on Sound Transit in the Seattle Post-Intelligencer and the Seattle Times, the nugget that stood out to me as important was this one, from the PI:

"A study by Sound Transit staff showed that rail [in the state route 522 corridor] would cost about $1.6 billion in 2005 dollars to build and attract only 6,700 daily riders in the year 2030. Bus rapid transit would attract significantly fewer riders -- 2,700 a day -- but would cost only about $110 million to build."

My calculator tells me that investing in bus rapid transit in this corridor yields one new rider (presumably, daily, for many, many years) for every $41,000. Investing in light rail in this corridor yields one new rider for every $239,000. Buses win!

Posted by Alan Durning | Permalink


Hi Alan,

First of all, I just finished reading "How Much Is Enough?" and "This Place On Earth," both of which were great reading. So kudos!

Secondly, and more on-topic, it's clear that bus and light rail both have advantages and disadvantages (and that planning a la Curitiba can keep bus rapid transit from being an oxymoron). Bus rapid transit also has an E.F. Schumacher-ish, right-sized feel to it, as your cost/benefit scheme bears out.

However, I would point out that (light) rail has a permanence to it, and that historically denser habitation corresponds to rail transit nodes. Central stations promote population density over the long term (which may be partly due to the economic demands of construction: communities have to encourage that density to pay for light rail).

So if you're concerned about containing sprawl, rail has more to offer than buses, I suspect. In fact, because of the cost/benefit breakdown you describe, buses can work to feed sprawl. It's easy to add another bus route, after all.

Every time I visit Switzerland, I always find myself remarking on the number of little towns on each rail line (and of course each town is served internally by bus). It didn't have to be that way, but there's something about the constraints of rail that seems to promote more careful consideration of resource allotment.

That's worth something, too, even if the intial price tag is more.

Posted by: Michael | Apr 15, 2005 10:33:18 AM


I appreciate your willingness to question what type of mass transit makes financial sense for our future. But it seems that your calculations fall prey to a classic mistake in cost/benefit analysis: not taking into account negative externalities, like air pollution and petroleum consumption. I certainly am not an expert on mass transit or on the negative externalities associated with each option, but deciding that buses win based on simple formula--cost of construction/new ridership--is too easy, and may lead us down the wrong mass transit path.

Posted by: Jill | Apr 15, 2005 11:22:02 AM

Actually the real infrastructure solution is not light rail but heavy rail.

Cities all over the country have been putting in light rail in recent years. Portland is an excellent example. But light rail is really 19th century technology in that the trains have to share space with cars on the city streets which greatly limits the size and length of the trains and speed at which they can travel. Downtown Portland is an excellent example. Anyone riding the famous MAX can tell you how long it takes to wind through downtown streets compared to say a ride on the Washington DC Metro, which is heavy rail.

Heavy rail trains are those that have a dedicated right of way so there is never any interaction with street traffic. And they generally are powered by a 3rd rail, which is one reason the right of way is totally closed access--so people don't get zapped. Because they operate on a closed system, heavy rail trains can be much longer and move much faster than light rail.

Because light rail trains share the city streets in places, they generally have overhead wires to keep them out of reach.

I'm not saying that heavy rail is the correct solution for Seattle. But if the city was really serious about high capacity transit it would be building fast high-capacity heavy rail along the I-5 corridor instead of messing around with light rail.

The monorail is a hybrid beast. It seems to use the dedicated right of way of traditional heavy rail with the lightweight medium-capacity cars of light rail. Monorail won't be fighting surface traffic but will never carry the capacity that a traditional heavy rail subway system can.

Posted by: Kent | Apr 15, 2005 11:38:06 AM


I'm glad you liked the books! Thanks for your comments. You raise an excellent and interesting point. I wholeheartedly agree that rail, bus, and other transit modes all have appropriate uses.

If rail actually yields better land use patterns than buses, that's a big plus. But the empirical evidence, in North America at least, does not suggest much sprawl-preventing benefit of rail.

Details are here:


The critical determinants of land-use patterns, it seems to me are: road construction, land use rules, and prices (fuel, cars, road use, land, taxes). Transit system investments are somewhere lower down the list of determinants. But let's focus on them anyway for a moment. I've been thinking through an argument that seems important.

BRT, as long as it involves a fairly permanent investment in bus-priority routes that will inspire basic confidence among private developers, can support compact development just as well as rail transit can. Experience in a number of communities such as Toronto and Ottawa show this.

BRT is also much faster to build, meaning that developers can move more quickly to capitalize on the market for transit-oriented development.

And, because BRT is faster and cheaper to install, and private developers can bank on it more quickly, it may actually have MORE sprawl-restraining influence than rail. Metro areas are always changing, but the first laying-out of development patterns on greenfields (streets and zoning, for example) rarely changes later.

So, even if rail were a somewhat more effective sprawl preventer than BRT in any given corridor, BRT might still be a more effective sprawl preventer in the real world of rapid and continuing sprawl--just because it's cheap enough to affect a much larger share of any metro area. That is, a metropolitan area can get a whole lot more of it installed in any planning period (of, say, 20 years). During that planning period, therefore, a much larger share of the metropolitan area will be influenced by the transit system (again, to the extent that transit influences land use patterns).

Rail, on the other hand, is so expensive and slow to build that sprawl in almost all of a metro area proceeds unaffected by it. By the time many decades hence when rail transit has actually been installed throughout a large metro area such as Seattle-Tacoma, the die has long-since been cast.

Posted by: Alan Durning | Apr 15, 2005 11:45:54 AM


You make a good point. Other costs beside financial need to be count.

But there's no evidence I know of that suggests rail is much cleaner than new buses.

New buses are pretty clean, even diesel ones. And especially hybrid diesel buses or hybrid biodiesel buses. Or natural gas buses. Or hybrid natural gas buses. Urban rail (like electric trolley buses) typically runs on (relatively clean) electricity, but it involves such a massive investment in energy-intensive infrastructure that it begins with a large energy deficit to make up. So I feel comfortable with a cash-only comparison in making this argument.

And, in case you're interested, blog readers discussed bus energy use and emissions earlier here: http://cascadiascorecard.typepad.com/blog/2004/12/hybrid_disappoi.html

Posted by: Alan Durning | Apr 15, 2005 11:53:28 AM


I'm disagreeing with you on this one. Urbanism is the solution to transport problems, not higher capacity or speeds. I'd choose LRT on city streets (a la MAX in downtown) any time.

Furthermore, in the particulars of the NW, MAX actually has a dedicated, segregated right of way for very large sections of its route, especially outside of downtown. And Sound Transit's Link Light Rail plan for Seattle (unlike Tacoma's shorter and already operating light rail) also mostly calls for segregated rights of way.

Posted by: Alan Durning | Apr 15, 2005 12:01:10 PM


I'm with Jill on this one. It's not the difference between the impact footprint of the buses vs. the light rail trains, it's the difference resulting from taking another 4,000 probably single occupant vehicles off the road.

I don't know if that tips the scales in the bus vs. train calculations, but I'd think it would be a significant factor.

What am I missing?

Posted by: jeffy | Apr 15, 2005 2:02:42 PM

Flexibility is missing from the calculation. I'm disagreeing with the LR proponents, as fixed rail cannot move to capture new construction, and if a neighborhood fails you have a large sunk cost. It is also easier to throw an extra bus at a stop if your monitoring shows increased ridership during certain hours.

Negative externalities for LR exist as well. I used to live in Sacramento, and the poorly-designed route crossed major arterials. The cars had to sit and idle while the train passed.



Posted by: Dano | Apr 15, 2005 3:50:45 PM

Hi Alan,

You make a very good point about the speed of implementation. It may simply be too late to consider rail, whether it's viable otherwise or not. And I should admit that, not having the foggiest idea where state route 522 is, I don't know what the specifics of this situation entail.

I meant to add my comment as context, rather than have it seem like I had a fixed view one way or the other, but I was heading out the door (catching the bus, actually) and didn't have time to precisionize my statementality.

I agree with you that you don't find much evidence for correlation between wise land use and rail in North America. (You also can't find significant investment in heavy rail for public transportation in recent memory, especially in these tumbleweed-strewn Western states, which might have impacted light rail development in its own right.)

I think I'm probably as impressed as you by the cost savings of bus rapid transit, though again that "rapid" part depends largely upon the willingness of a community to give buses right-of-way priority.

As Clark was just saying, it's very difficult to predict how these things will work out, which may be as good an argument as any for a bus network, which has the virtue of being scalable.

PS: Thanks for the link. Boy, that aide is kinda touchy! Yikes.

Posted by: Michael | Apr 15, 2005 4:02:56 PM


Well done twist of my argument!

I'm pretty familiar with the literature on the lifecycle costs of driving, and those costs are pretty darn high. But I don't think they're equal to a net present value of a quarter million dollars per vehicle. So I suspect I still win the argument, even if we count everything your way.

But the larger point, and the better argument is this: Given that public dollars for transit investments are limited, I'd vote for doing BRT on lots of corridors rather than LRT on a few. That's the way to get the maximum number of transit riders for the minimum cost.

If resources were unlimited, you could just do LR in all corridors because it gets the most riders. (And heavy rail would probably get even more, so you'd do that, right Kent?) But resources are most certainly not unlimited. They're very limited. There's even a risk that committing to an expensive LR solution will end up sucking money away from buses, as happened with LA's rail transit system.

Now, my views are actually less doctrinaire than this: we ought to be thinking about a total package that judges each corridor by its own circumstances. But, since we're making the arguments . . .

Posted by: Alan Durning | Apr 15, 2005 4:09:45 PM

Thanks Alan, I don't expect to win any arguments about transit tradeoffs with the author of _The Car and the City_. ;-) But that's exactly why the simple cost-per-rider calculation seemed out of character. I guess in this case, the implementation costs are so vastly different that they swamp the usual ignored costs. My intuition isn't up to the complexity of the situation.

Posted by: jeffy | Apr 15, 2005 4:58:11 PM


I'm not actually advocating heavy rail transit for Seattle, only saying that if you actually want to build transit INFRASTRUCTURE then a a real heavy rail metro is the best. I've lived in both DC and Seattle and the difference is remarkable. I was carless in DC and didn't really every miss it. My commute from my apartment in Dupont Circle in central DC to the NOAA offices in Silver Spring MD was 20 minutes on the red line and there were trains every few minutes. Once you found the nearest metro stop you could get anywhere in the city in rapid fashion. People used the metro day and night for every reason including going out at night. Most of those trips are car trips in Seattle because while it's possible to live without a car in Seattle, it seriously restricts your mobility.

Now Seattle is a medium-sized city and a real metro is far beyond the dreams of even Sound Transit. But if the city continues its growth trajectory it will eventually need to come to grips with serious mass transit. Maybe not in 20 years, but certainly in 50 or 100 years.

As for building subways? It's simply a matter of priorities. My wife is from Santiago Chile where we visit every year. Santiago has a beautiful subway and they are expanding lines in every direction. If a medium-income country like Chile can afford subways then cities like Seattle most certainly can. Of course with the current anti-tax attitude it will never happen. But that doesn't mean the region couldn't afford it if the will was there.

Posted by: Kent | Apr 15, 2005 6:14:43 PM


I think you have missed one important factor - the cost in energy use per passenger mile. In this rail transit has it all over both autos and buses. I live in Portland, Oregon, where we have both light rail and buses. Even with having to slow down for street travel in the downtown area I prefer light rail to any other available transportation. Having spent a fair amount of time in the Washington DC area and ridden the Metro there, I definitely prefer the heavy rail approach, but heavy or light, rail is the best way to go in my opinion.

Posted by: Hank Bennett | Apr 15, 2005 10:06:16 PM

Sorry, Alan, but your softball comments are little more than a shill for Sound Transit. I sat before that board during the $1 billion overbudget scandal and urged them to build the south segment instead of the tunnel, and regret it! I stressed the need to serve South Center with the direct route, but the board approved the bypass alignment, "claiming it would save money", though the moderate extra expense is justified due to existing ridership and planned development there.

Please don't say "a spur to South Center will be built later" bullcrap. The principles of New Urbanism apply best at the Regional basis. Avoiding this Regional destination ruins Link's potential, period. This is one example where you did nothing to guide growth and help the LRT investment serve the most people.

One concern I have about the Times Article was the planned HOT lanes on 99. Just how well will transit users enjoy walking to the bus stop (or anytime) while zooming traffic is mere inches away in the widened curb lanes? And how much wider and how much more difficult to cross, will 99 become with the new lanes?

Whether rapid transit is LRT or BRT or monorail, the most important consideration is how it serves growth and development. If rapid transit merely serves as commuter lines to downtown, in Hub-n-Spoke fashion, development between suburb and urban core remains imbalanced and results in even greater need for long-distance travel at all times and for all needs, limiting ridership and negating effectiveness of the investment. such is the case in Seattle's transit proposals.

Posted by: Art | Apr 16, 2005 3:26:55 PM

Little bit of confusion here. BRT is NOT rapid transit, if you don't build the dedicated-lane infrastructure to separate the busses from the other traffic. If you DO build that infrastructure, you might as well install light rail.

If you build appropriate infrastructure and use busses, you have high labor costs at one driver for 100 passengers, while rail easily handles 300 passengers for one driver.

In other words, bus transit is slow and uncomfortable, which may account for the projected ridership cited being about one third of the projected ridership on light rail.

Frankly, I don't see Alan as an objective no-ax-to-grind observer. He refers to "long-term benefits per dollar spent" and "a fairly permanent investment in bus priority routes", while he is comparing expenses between light rail that does have that permanence, and a BRT proposal that does not. Writing in such way that only the well-informed reader can spot the questions that are left unanswered is interesting to the well-informed reader (but not because they're learning anything new), and uninformative to the lay reader, who can't really understand what has been said.

Posted by: serial catowner | Apr 17, 2005 1:08:02 PM

Incidentally, Dano is wrong too, in claiming that it's easier for a bus route to expand capacity. To add an extra bus you need to add an extra driver; when you add another light rail car the same driver serves the longer train.

Posted by: serial catowner | Apr 17, 2005 1:10:42 PM

Hank's right: in energy use per passenger-mile, urban rail does a bit better than urban bus. (On average in the United States, as of 2000, urban rail transit uses about 3,000 BTUs to move each passenger one mile. City buses use about 4,500 BTUs to do the same job. In Japan, rail outperforms bus by a larger margin.) I don't have at my fingertips the numbers for "seat-miles," that is, simply showing the energy required to move the vehicle and factoring out how many passengers are on board. But I do know that intercity buses in the United States are the most efficient form of long-distance transportation, beating Amtrak by a large margin. (And the explanation, of course, is that intercity buses succeed in running fuller than do intercity trains.)
(You can read more about this at http://www.lafn.org/~dave/trans/energy/fuel-eff-20th.html )

You need very high densities to make rail live up to its potential. Asia and Europe has those densities. So, far North America doesn't.

But, returning to a larger view, in city-wide energy efficiency, bus-v-rail is inconsequential compared with either-v-car. So I think it's appropriate to focus on the metric of public-dollars per new rider, the original metric that kicked off this post.

Serial Catowner: Hmm. By your definition light-rail isn't rapid transit either, since it can operate on city streets where other traffic can theoretically interfere. As the original article that I posted on indicated, bus transit ranges widely. It's a continuum from regular buses on city streets to space-age buses on separate guideways with their own "third rail"--essentially trains on rubber wheels. High-end BRT is expensive, but I disagree that high-end BRT is the only viable competition for LRT. We ought to look across the full range of options, from modest adjustments to existing city buses to segragated bus routes and rail lines on key corridors. This overarching discipline of making best buys first is Least-Cost Planning.

When I think about protypical BRT, I think of a blend of HOV/HOT lanes, separate bus lanes, special exit ramps, buses on city streets, and things like signal preemption (where buses can trigger green lights for themselves).

Finally, on operating costs, drivers per passenger is just one factor. Other things add up. The most recent numbers I've seen, for example, show Tacoma Link Light Rail with operating costs of $5.30 per one-way passenger trip, where the average trip is under one mile. King County Metro Transit (which is all buses) has operating costs a little under $4 per one-way passenger trip, and the average trip is around four miles. Operating cost per passenger mile, therefore, favor bus over rail by a factor of more than five to one (~$5.30/mile v. ~$1/mile).

And ultimately, operating costs devoid from capital costs are a mere curiosity. For example, it costs very little to operate the energy systems on the space shuttle, which employ platinum fuel cells and solar PV. But building them cost millions of dollars. Their low operating costs doesn't make them a cost-effective model for life here on Earth.

Posted by: Alan Durning | Apr 18, 2005 8:19:37 AM

Well, having read (and perhaps unfortunately, purchased) well over 500 books about railroads, there is one thing that stands out above all others- any disadvantage in operating efficiency will kill you in the long run. That is the second major factor in making rail expensive (the first being acquisition of the right of way). You can build rail lines with all kinds of operating inefficiencies that reduce first cost, but nobody does any more, because this lesson is so prominent.

There undoubtedly will be differences between the effects of gradient and curvature and the effects of labor costs, but if you build your rail line well, the savings from gradient and curvature reductions last the life of the system, no matter how much traffic increases. OTOH, if you built a BRT so well that ridership kept growing, your labor cost would keep growing right along with it. And, because each bus is a separate entity, signalling and traffic management costs (and the effect on any shared roadway) can rise dramatically.

However, you can also do the short form, and your BRT is like an ice cube in the sun- every time you look at it, what you're going to get is less.

A lot of this, in my opinion, is of less interest to us than the effect of the choice on land-use planning. With rail you have a tangible committment to the future. The bus, to this day, is touted as a service that can be changed or discontinued. Choose buses and you lose your best tool to persuade people, rather than telling them, to build near transit.

For the benefit of newbies, there is nothing new about the BRT idea, which has been around since the early 30s, when buses first got strong enough to hoist themselves up a medium-sized hill. There are lots of studies; at one time Pittsburgh used abandoned rail right-of-way to build 'busways'. How that turned out for them I can't say, but nobody has duplicated it on a significant scale, so apparently it wasn't too convincing.

Los Angeles and Boston are now currently running "BRT" and Boston has produced some ridership satisfaction studies. Of course, you need to check the details because just about anything with rubber tires can squeeze into the BRT tent.

And there'll be plenty of chances to talk about it, because BRT has more lives than a zombie in a horror movie. Or you can just wait and see where people move when gas gets expensive and they want to live near good transit.

Posted by: serial catowner | Apr 18, 2005 4:37:43 PM

I should add that I really appreciate the work Alan is doing to host this blog, and his posting this subject for discussion. Naturally, as almost a lifelong student of transit, I consider the subject extremely important. Unfortunately, we may soon get the chance to discover if I'm right in doing so.

Posted by: serial catowner | Apr 19, 2005 10:09:47 AM

My thanks as well to Alan for hosting this blog. It is interesting that in all of these posts, no one has mentioned the real world exercises going on about transportation in our area. Currently the legislature is debating a transportation package. There are many needs in this area for both transit and roads and the balance is key given the finite tax dollars we have to spend. Two projects, the viaduct and 520 are urgent safety needs. Some believe we can do without the viaduct, but I don't think it can unless. And there are a few traffic bottlenecks that should be fixed. But the vast list of projects are sprawl inducing capacity projects like the valley freeway and I-405 expansion.

Meanwhile, Sound Transit is debating their long range plan and has studied corridors and competing technologies throughout Puget Sound. Light rail fares well to downtown Bellevue and along the I-5 corridor. BRT looks good for 520, Aurora, from Bellevue north and east to Issaquah. Monorail doesn't work to cross the lake. You can quibble with their methodology, as no doubt some of you will, but this is the best picture to date of costs and riders for different modes. I urge all of you to look at the reports on the ST website.

This is a crucial time for this region. Light rail will be built south and shortly after to downtown Bellevue and to Northgate. We need to decide now how to find the best mix of mass transit solutions for other corridors. BRT can be many things. When folks tout the low cost of BRT, they are talking about not-so-rapid BRT operating in HOV lanes. When they talk about the ridership they often use dedicated ROW's which are almost as expensive as rail. I support rail investment because I believe its permanence and customer satisfaction offer much more ability to target growth around station areas than BRT.

One must accept that there is no magic solution. Every course has advantages and disadvantages. Monorail folks like to say "rise above it all" but that means street blight, lack of integration with neighborhoods, smaller stations, limited expansion. Buses are relatively cheap, but many folks simply won't ride them and they don't have the same perception of reliability and permanence. BRT lanes will always be an attractive target to convert for general traffic. Light rail can be pricey if it is in a tunnel or elevated. Choose with your eyes wide open, not with ideological blinders.

Posted by: bfree2think | Apr 19, 2005 11:35:40 AM