Against Light Rail

Don't have a rail corridor handy? Don't build light rail. By the time congestion is bad enough for a metropolis to think about light rail, land costs are too high for any 'greenfield' corridor, and using existing right of way is the only feasible way. 

If the only existing right of way is public street, why spend the money to build a electrified railway? Electrified traction has undeniable perks over rubber-tired buses (fuel costs, acceleration, comfort), but the cost is rarely worth the marginal benefit.  

Neither ride comfort nor transit signal priority (TSP) nor dedicated/reserved guideway are specific to rail. Nor level boarding or off-board fare collection. With double-articulated buses, the rider capacity/driver ratio rail previously offered over bus has largely evaporated. 

So why do places like Portland keep building light rail? I suggest an availability heuristic: They have lots of old freight rail lines to convert to light rail. I seen symptoms of the same disease in Utah, and efforts to bring light rail to Utah County. 

The only actual advantage of rail over bus is political: its easier for a metro to create rail rapid transit than bus rapid transit. In the public imagination, light rail vehicles are like freight trains, whose necessary separation from cars is implicitly accepted. 

It is the separation from cars that the true virtues of rapid transit emerge - speed, safety and reliability. Rapid transit requires exclusive/dedicated guide way--exceptions generate accidents reliably, whether in travel lanes or turning lanes.  

So it's politically feasible for a light rail to claim a lane a lane on a congested arterial in a way no mere bus could ever attempt. That said, double-articulated buses seem to be able to make some of the same claims to exceptionalism and necessary special accommodations.  

wiki on BRT:

As this will probably fall afoul of wikipedia's ban on primary research, thought it was worth repeating:

When TransMilenio opened in 2000, it changed the paradigm by giving buses a passing lane at each station stop and introducing express services within the BRT infrastructure. These innovations increased the maximum achieved capacity of a BRT system to 35,000 passengers per hour.^[44] Light rail, by comparison, has reported passenger capacities between 3,500pph (mainly street running) to 19,000pph (fully Grade-separated). "From these findings … there is little evidence to support the view that [light rail] can carry more than busways.".^[45] There are conditions that favor light over BRT, but they are fairly narrow. To meet these conditions you would need a corridor with only one available lane in each direction, more than 16,000 passengers per direction per hour but less than 20,000, and a long block length, because the train cannot block intersections. These conditions are rare, but in that specific instance, light rail would have a significant operational advantage. However, "... any perceived advantages of [light rail] over BRT are primarily aesthetic and political rather than technical … due to the perceived capacity constraint of BRT there are currently no cases in the US where [light rail] should be favored over BRT."^[46]

 44) W. Hook, S. Lotshaw and A. Weinstock (2013). "More Development For Your Transit Dollar. An Analysis of 21 North American Transit Corridors" (PDF). Institute for Transportation and Development Policy. p. 20.

 46) W. Hook, S. Lotshaw and A. Weinstock (2013). "More Development For Your Transit Dollar. An Analysis of 21 North American Transit Corridors" (PDF). Institute for Transportation and Development Policy. p. 21.

LRT vs. BRT

To built more Rapid Transit, it should be BRT rather than LRT. Bus Rapid Transit is simply cheaper per mile, which means more of it for the same price.

LRT's advantages are as much political as technical.

First: LRT's primary advantage is that it can use rail corridors to achieve rapid transit status. Cars can't use railway right of way, so there is no competition with cars. This advantage is not limited to LRT. As both the BRT tunnels in Pittsburgh and the Orange line in LA have shown, BRT can use railway right of way quite well. Buses, driven by professionally trained drivers, can pass each easily in 22' (11' per bus). I recall the buses in Eugene, Oregon, coming scarily close. (Railway right of way is only ~22' wide at different points, which is too narrow for even two lanes of car traffic 10' lane + 10' lane + 8' safety area + 8' safety area). Word on the street is that international Fire Code mandates 26' of clear space as necessary for emergency operations.

Second, LRT vehicles are heavier, so they stop more slowly, which makes sharing a lane with cars much more dangerous, especially at high speeds, and consequently less likely to happen.A train in a highway median gets to keep its separated guide-way, and no crank(y) politician can change that. BRT 'Freeway Flyers' (BRT in an exclusive freeway lane) inevitably become BRT in a HOT lane, with consequent degradation in speed and reliability. Trains don't have the problem.

There may be one area where LRT has an actual advantage: Elevated track, with very right clearances. There have been experiments with 'guided' BRT, using things like optical sensors, guidewheels, or specially constructed guide-track. 'The Gap' between vehicle and platform can be an issue, and I'm not sure how well BRT does in that regard.

However, a 'train' portion (exclusive/separated) guideway is expensive. Denver, Seattle, and LA all achieved it by putting light rail in freeway medians. LA is increasing achieving it through the use of elevated lines (albeit at very high prices). Seattle has tunneled, at a cost of over a hundred million dollars a mile.

Previously, I've talked only about 'Rapid' transit in separated/exclusive guide-way. If we want to talk streetcars, it's only fair to compare them with their wheel counterpart, buses. The advantage of streetcar is (again) political. Chambers of Commerce like streetcars, due to their permanency. They are also cheaper and less politically fraught. A 'tram'-type light rail (AKA street-car) is cheap, because it runs in dedicated/mixed traffic right of way. So there is no need to take right of way from cars, or eliminate parking. But this type of right of way comes with costs. It makes the service slow and unreliable--it's like a bus on steel wheels.

Streetcars are also (politically) easier to build, because the FTA helps pay for them. Streetcars can get 50% FTA funding for capital expenses, such as vehicles, TSP, and station platforms. There is no reason a bus couldn't enjoy these same benefits.

A Concise History of Rail Transit in America

Modern transit comes from two historic lineages: Steam railroads, and horse-cart street railways. To operate in an urban environment, steam railroads underwent a number of modifications. To reduce conflicts with street level traffic, were either elevated or under-grounded. At some point, they were also electrified, typically use a third-rail system. Once that occurred, expansion required the continued use of grade separated, exclusive guideway, so no one touched the third rail and died. In contrast, street railways were electrified as trolleys, using a pantograph. (Cable-cars can be thought of as a 'dead branch' alternative to electrification). The converging modes of electrified heavy rail and street railways were hybridized as the "Inter-urban". Electrified the whole-way, using a pantograph, and running in a mix of at-grade and tunnels. After the second World War, almost all pure street running 'trolley' systems were 'bus-tituted' out of existence, while some inter-urban systems survived. The survivors all had some off-street running-way, viz: RTA Streetcars, San Francisco cable car, MBTA Green Line & Ashmont–Mattapan High Speed Line, SEPTA Subway–Surface Lines: Suburban Trolley Lines & Girard Ave Trolley, RTA Rapid Transit: Blue and Green Lines, Newark Light Rail, Muni Metro. Between ~1930-1972 is sort of a 'Dark Age' for urban rail--almost nothing new is built. Then there is a resurgence of heavy-rail systems to deal with traffic congestion: BART (1972), Washington Metro (1976), MARTA (1979), Baltimore Subway (1983), and Miami-Dade (1984). All run at-grade in the suburbs, and in tunnels in the city center. About 1980, America adopts the Stadtbahn/'City Rail' concept from Germany, and APTA coins it 'Light Rail'. It runs at-grade in the suburbs, and at-grade in the city-center, like the inter-urbans. Being regulated as 'light' rail, it is allowed to operate in mixed-traffic with cars, making it easier/cheaper to build. Over time, the surviving inter-urbans are rebuilt/revitalized, making use of the same vehicles as the new 'Light Rail' systems. Circa 2001, Portland reinvents the 'streetcar', which runs at-grade, in mixed traffic, with smaller vehicles, and making extensive use of single-track.

Now, to get back to what is 'Rapid' transit: Rapid transit is something that has it's own (unshared) guideway. Subways, elevated rail, commuter rail all clearly meet this standard, as do most of the 'Metro' systems of the 1970's heavy-rail revival. But the surviving inter-urbans and new light rail systems are a confusing mix: They have portions of exclusive guideway, so they have rapid transit portions. But LRT means 'Light Rail Transit' rather than 'Light RAPID Transit'. This gets confusion in the context of BRT, which actually means 'Bus RAPID Transit'. BRT gets developed in Latin America as a sort of bus version of a heavy rail system--buses with unshared guideway. But that's another topic. In summary: HeavyRail = Rapid, Streetcar !=Rapid, LRT !=Rapid...but does have sections that could be. (Cable-cars get lumped in with LRT largely on the basis of Cable-car != heavy-rail.)

And finally: Metro!=Heavy-rail, but Metro ⊂ Heavy-rail. Freight, Metro, Subway, Elevated, Commuter Rail ⊂ Heavy-rail.

=     Equal to
!=    Not equal to
⊂    Is a subset of.

What is Light Rail Transit?

Almost all transit built in the United States since 1980 has been ‘light rail transit’ (LRT)--but ‘light rail’ is a regulatory classification for a vehicle, not a type of transit. The term ‘light rail transit’ covers a wide range of types of propulsion, guideway, and operating characteristics. A clearer articulation of the characteristics of different light rail systems would help to better determine the relationship between transit investment and associated outcomes.

The US is slowly emerging from a transit Dark Age. The combination of subsidized competition and public dis-investment effectively expurgated most urban passenger rail systems from existence. It is necessary to re-invent, or rediscover, the constitutive elements of effect transit systems. Historically, there have been many different types of rail transit systems, but they fall into a small number of distinct types, which might be called suburban railways, street railways, rapid transit systems, and tram-trains.

Suburban railways link major cities to suburban locations distant from the central city. They linked independent towns to a nearby major city. Suburban railways are characterized by high speeds and a very limited number of stops, and characteristically bypassed the outer edges of an urbanized area to reach a central location. The require exclusive guide-way, but their relatively infrequent operation (hourly) means that this requirement can be met through temporary physical separation (crossing gates) rather than the full cost of grade separation.

Street railways develop from the horse-cart service. Initially steam powered, the nuisance presented by the smoke and cinders meant that almost all systems were eventually electrified. Acting more as labor-saving devices, they acted as a ‘pedestrian extender’, rarely traveling much faster than a running man, and stopping frequently. In Europe, the modern implementation is known as a ‘Tram’; in America, as a ‘Streetcar’.

Rapid Transit systems represent yielding to necessity. In locations where cost or difficulty of obtaining sufficient surface right of way (viz: London, NYC, Chicago) underground or elevated construction was necessary. Full grade eliminates the need for sudden stops, making much higher speeds possible. The lack of cross-traffic also makes much higher headways possible, so that it is possible to run a very large number of trains on the same section of track. A bare handful of metropolitan areas have been able to fund the construction of new rapid transit corridors.

Tram-trains operate as railways outside of cities, but as street railways within them. Adapted from the ‘City-Rail’ system in Karlsruhe, Germany, it represents the revival of a historical form of American transit, the ‘Inter-urban’. Inter-urban’s were passenger rail lines running along freight railway right of way between cities, but on city streets within the city. They represent an effort to reduce the friction of transportation, by obviating the need for a mode-switch from train to tram at the edge of the dense, pedestrian oriented central core.

Every implementation of mass transit system represents a trade-off between cost, speed, and access. Evidence suggests that the trade-offs are not entirely granular, but rather represent a series of ‘market niches’ or functional classes of transit. The same classes of transit emerge independently, repeatedly, in different locations, at different times. Analyzing the characteristics of light rail determines that there are ‘functional classes’ of LRT, with different service characteristics, which resemble the service characteristics of historic transit modes.