Human Transit

san diego: the rail-bus balance

The Transport Politic has a good overview of the recently announced rapid transit plans for San Diego.  The plan, in short, is to add only one more line to the region's light rail system, a long northward extension to the huge University of California San Diego (UCSD) campus.   For other corridors in the region, the focus is Bus Rapid Transit.

(Legend:  Black = existing commuter rail.  Thin pink lines = Bus Rapid Transit.  Dashed blue line = proposed LRT extension.  Solid blue, green, orange = Existing light rail.) 

I suspect the plan reflects the influence of the locally based Alan Hoffman, an energetic and informed advocate of the Brisbane model of Bus Rapid Transit (BRT), a model I've discussed at length here.  (Hoffman was a key author on a readable 2008 survey of BRT around the developed world, downloadable here, that endorses the Brisbane model for North American cities, including San Diego.)  Brisbane features largely grade-separated busways capable of very high freqeuncy and reliability but also capable of running buses through to many destinations at the outer end of each corridor.  The Brisbane model works well where you have (a) a reasonably dense corridor, extending outward from downtown, where (b) a separated busway is physically feasible but where (c) there is no single overwhelmingly important transit destination at the corridor's outer end.

By that principle, the San Diego plan looks right to me.  Light rail is to focus on extending to the biggest transit destination in the county outside of downtown, UCSD, and ending there.  A link from downtown to UCSD will have balanced, two-way demand flows all the way to the end of the line, a very good geography for rail transit with its fixed high capacity and attendant fixed infrastructure cost.

But corridors that don't have a strong outer endpoint will benefit from a pattern in which high frequency runs along the corridor but can branch in several directions as you get further out from the city and demand grows more diffuse.  This is certainly the case with the I-15 and South Bay corridors as sketched. 

The Mid-City corridor along Park and El Cajon Blvds., which focuses mostly on inner-city fabric, is more debatable.  It does have a strong outer endpoint, San Diego State University, and it also serves San Diego's great central park, Balboa Park, and the famous San Diego Zoo.  It probably could be light rail, or even some form of streetcar, so bus-based solutions should probably plan for convertibility to rail in the future, as capacity needs dictate.  Note, too, that what's proposed for Mid-City is "low-end BRT," similar to the Los Angeles Metro Rapid, where signal priority is the primary means of giving buses an advantage. It's hard to create exclusive lanes on inner-city streets, especially in the early stages of network development, but Rapid Bus service can be a sensible step in that direction.  By doing what can be done to increase patronage without exclusive lanes, it helps build the argument for exclusive lanes in the future, much as it is has done on Wilshire Boulevard in Los Angeles. 

There may be, as the Transport Politic suggests, some bias against spending too much money in the dense inner city, and/or against short corridors, in the region's planning politics; some such bias is inevitable in large urban regions where the inner city is a small part of the political picture.  It will be intersting to watch Mid City plans evolve in more detail.  This corridor is already dense, but also likely to see further urban redevelopment, much like the Pearl District in Portland.  If such development can be harmonized with locally oriented Bus Rapid Transit -- doing what a streetcar does but on tires, and a bit faster and more reliably -- it will be an important data point for similar inner cities across North America.

bus vs rail, an "oversimplified comparison"

Planetizen points out a new paper by Jeffrey R. Brown and Gregory R. Thompson of Florida State University, called "Bus vs. Rail: an Oversimplified Comparison."  From the abstract:

There is debate about the relative merits of investing in rail or express bus modes to improve regional transit performance. The debate largely assumes that both modes serve a single function of providing higher speed service to the central business district (CBD) over relatively long travel distances. The debate generally overlooks other functions that might be served by express bus and rail transit modes and thus ignores that the two modes may perform differently depending on the service mission they are assigned. Performance of the two modes is examined in four metropolitan areas with different strategies for providing high-quality, regional transit service: a CBD-focused strategy, a hybrid strategy that serves the CBD and a few other destinations, and a multidestination strategy that serves a widely dispersed set of destinations. ... It was found that the combination of a rail transit backbone and a multidestination service strategy leads to better performance than any other marriage of mode and mission.

In other words, (a) rail and bus technologies are tools, and no tool is right for every job, and (b) multi-destinational networks based on connections are more productive than radial systems that narrowly focus on a single downtown.  Regular readers of this blog will find these conclusions obvious, but it's interesting to see that this argument still needs to be made in the literature. 

UPDATE:  Let me tease this apart a little further.  I don't mean to imply that the work is redundant, but it does apply to a narrow range of cases, and it conflates "multi-destinational" with "rail" a little more than I'm comfortable with.

The authors' focus is on four cities which they locate on a spectrum from "CBD-oriented" to "multi-destinational."   

• Pittsburgh, which they identify as the most "CBD-oriented."
• Minneapolis, which they identify as transitional or hybrid.
• Atlanta and San Diego, which they identify as "multi-destinational."

These cities are all comparable in size, all have a mix of rail and bus, and all have some facilities for getting express buses out of traffic at least some of the time, ranging from the full busways of Pittsburgh to the freeway-shoulder operations of Minneapolis.

A CBD-oriented system (more commonly called a radial system) is one that views downtown as the sole destination of importance.  In such a system, people who aren't going downtown usually have to go via downtown, whether or not this is on the way.  A multi-destinational system is one that tries to serve trips to many destinations all over the city.  If you live in Los Angeles or Manhattan or Paris or Berlin, this distinction will seem silly to you, because your city has been multi-destinational for decades if not centuries and your transit system adapted to that reality long ago.  But most American (and Australasian) cities had a period, generally ending around 1945, when they had a single extremely concentrated downtown -- fueled, in many cases, by streetcar/tram networks that converged on it.  And at one time, it made perfect sense that this downtown would be the sole focal point of the transit network.

Since 1945, most cities have been becoming more multi-destinational, with more important destinations (employment, retail, leisure, etc) scattered all over the city.  Transit agencies were generally slow to adjust, especially since downtown tended to be where they were most appreciated and where the pre-car development pattern made it easy for pedestrians to get to them.  But over time, it's been necessary to adjust to a multi-destinational pattern in order to remain relevant to the life of the city as it is now.  The paper suggests that of the four cities studied, Atlanta and San Diego are relatively far along on that path, Pittsburgh least so.  (This seems to match Alan Hoffman's observation (here, page 67) that despite the introduction of busways, the Pittsburgh network has changed relatively little for a long time.) 

Note that the important distinction here is not that the network infrastructure is more or less CBD-oriented, but that the thinking of the transit agency is.  All four of the cities studied have CBD-oriented transit infrastructure that suits their CBD-oriented history, but they have thought about their networks in different ways. 

By comparing the experience of these four cities, the authors find that the most effective system is not the CBD-oriented but the multi-destinational.  Needless to say, your mileage may vary; it depends on how CBD-oriented your city still is, but even a city as CBD-oriented as Portland had great success with a multi-destinational network.  Most of the major network redesigns I've done have been about helping CBD-oriented systems still meet their CBD need while also being relevant to a wider range of destinations. 

My only quibble is that multi-destinational systems don't have to mean "rail and bus working together" because you can do the same thing in smaller or pre-rail cities by designing an all-bus system to work just the way a good bus+rail system would work.  I was the lead planner on a redesign for San Antonio around 2001-2, shortly after their voters had rejected light rail.  We did what we could to create a connective frequent network given that they only had buses to work with.  Following Portland's model, we did this with a mixture of high frequency grids in the denser inner city and trunk-and-feeder systems in the outer suburbs.  As a side effect, that project helped to intensify and simplify services in a concentrated corridor (Fredericksburg Road) where they're now planning Bus Rapid Transit, and light rail is being talked about again. 

Portland, too, did it with buses first.  Their multi-destinational route network (including the frequent grid covering the inner city and the trunk-and feeder structures for major outer suburbs) all were put in place by 1982, four years before the first light rail line opened.  Rail sometimes leads, but sometimes the result of good multi-destinational network planning, not its cause or starting point.

will a busway give me direct service to downtown?

In my post on Brisbane's King George Square busway station, I emphasized that the service pattern was of few routes running at high frequencies.  Michael Setty commented

What is really happening in Brisbane contradicts the marketing pitch made for so-called "Quickways" (grade-separated busways) by www.movesandiego.org, which emphasizes so-called "world best practices" focusing on the ability of buses to operate directly from origin to destination ...