When the city of Wellington, New Zealand, decided to expand its public transit system, Mayor Celia Wade-Brown initially favored light rail as the so-called sexy option. Then the project estimates came in. According to the Dominion Post, the capital budget for light rail came to $940 million, while those for bus rapid transit came to $207 million. And this despite the fact that BRT was expected to reap a greater return for the city.

That was enough to convince Wade-Brown, who subsequently called BRT "nearly as sexy as light rail and a lot cheaper."

BRT and light rail are often considered side-by-side when a city decides to enhance transit in a densely populated corridor or build an entirely new system for the metro region. To be sure, they have many similarities, including (when done right) exclusive lanes and attractive stations. Light rail proponents typically point to capacity and style as selling points, whereas BRT proponents often point to price.

While the relative costs of BRT and LRT have been studied for years — with the GAO finding [PDF] more than a decade ago that BRT was indeed generally cheaper, at least when it came to capital construction — researchers have yet to explore their relative popularity among riders. In other words, all else being the same, do riders really prefer one of these modes to the other?

Well they kind of do but they mostly don't, according to new work by Graham Currie and Alexa Delbosc of Monash University in Australia, published in the latest issue of the Journal of Public Transportation [PDF].

To make their comparison, Currie and Delbosc gathered data on 44 BRT systems in Australia and 57 light rail systems (including streetcars) from Australia, Europe, and North America. They measured success in terms of passenger boardings per kilometer during the years 2001 to 2009. Then they considered a number of variables — from service level to city density to car ownership — that might also influence ridership in the metro region.

Based on boardings alone, light rail had a clear advantage, scooping up more than six riders per kilometer to just about one rider for the same distance on BRT.

But when outside factors were brought into play, there were six in particular that significantly predicted ridership. Three were directly related to better service: trips per year (a proxy for arrival frequency), integrated ticketing (which belies a strong network), and vehicle capacity. In fact, report Currie and Delbosc, when the greater capacity of light rail cars was accounted for, the difference in mode (BRT versus light rail) no longer predicted ridership:

This suggests that routes with higher service levels are more efficient and attract more ridership than low-service routes, all other things being equal.

So once again we see that good service, above all, is the key to good transit. Most experts will tell you that the better a service rivals the convenience of car travel, the better its ridership numbers will be. As transit planner and author Jarrett Walker is fond to say, frequency is freedom. Currie and Delbosc put things this way:

Results suggest that the transit mode does not directly impact ridership but rather acts through vehicle size and service levels.

(The other three significant ridership factors were the system's presence in Europe, where transit has a higher mode share and cities are generally more walkable; employment density, for obvious reasons; and slow speeds, which might seem like a counterintuitive finding but is probably just a signal of dense corridors.)

Now, as always, there are limitations to this work. The biggest is that Currie and Delbosc only studied BRT systems in Australia, which hurts their attempt at a universal comparison. Additionally, while car ownership didn't predict light rail or BRT ridership in their analysis, it might be more instructive to look for a link with car vehicle-miles traveled, or even better, with total highway mileage in a metro region. The variables here might also be too numerous to draw a clear conclusion.

Still the work suggests that cities like Wellington have a strong case for choosing BRT over light rail when it comes to transit expansion, especially when they're strapped for capital cash. That's not to say light rail doesn't have its own benefits; as we've written before, it certainlydoes. But riders may ultimately not really care how sexy a transit vehicle is — provided it picks them up soon and takes them where they need to go.

by Eric Jaffe

> via The Atlantic Cities