Making Elevated Rail Work

Everybody hates els. They’re ugly and noisy and cities will even move their train station away from downtown to tear them down. The hypocritical treatment of els versus much wider and noisier elevated highways is fortunately the subject of another post, on Market Urbanism. I would instead like to discuss how elevated rail could be made to work in cities, allowing the construction of rapid transit at acceptable cost.

One way viaduct structures can be made more acceptable is if they’re branded as a new technology. This is the case of Vancouver’s SkyTrain, the JFK AirTrain, the Honolulu light rail line, and monorails. Another is if they’re along rights-of-way that are already considered blighted, such as freeways; this also helps explain why the JFK AirTrain was built whereas the proposed subway extension to LaGuardia was not.

As a first filter, the above examples suggest that the most useful elevated rapid transit – grade-separated mainline rail, or els over major streets – is impractical due to community opposition. But as a second filter, we could simulate some features of both cases in which viaducts are more acceptable – new technology and freeway right-of-way. If we build a well-designed and aesthetic arched viaduct over a wide road, this could pass community muster. For example, Robert Cruickshank prominently used the second and further photos in this CAHSR Blog post to argue that grade separations on the Peninsula will not be a blight. The 7 viaduct in Sunnyside is also a good example of an el.

As a third filter, the success of the elevated train over Queens Boulevard comes precisely from the enormous street width. East of Sunnyside, Queens Boulevard becomes practically a highway, nicknamed the Boulevard of Death and excoriated on Streetsblog for its lack of pedestrian scale. At the same time, the 7 above Roosevelt Avenue darkens the street and the steel el structure is very noisy. But when there is an el about Queens Boulevard, everything works out: the street is broken into two narrower halves, with the el acting as a street wall and helping produce human scale; the el is also farther from the buildings and uses an arched concrete structure, both of which mitigate its impact.

It’s possible to mitigate even further and imitate the methods of the AirTrain or SkyTrain. Those use modern viaduct construction techniques and are therefore relatively unobtrusive: see for example this photo on Greater City: Providence, in the context of reinstating some of the elevated infrastructure torn down in the 1980s. Even if the technology is your standard railroad, newer viaducts can reduce impact. In addition, the old els were built with very tight curves, producing squeal; building with wider curve radii is the norm today, and although it increases visual impact and can require more takings, it reduces noise impact, often to practically zero.

Commenters from various Northeastern suburbs have told stories of how people don’t even notice the electric regional trains, but complain about the freight trains. Of course those regional lines were built in the 19th century, but they were built to mainline standards, rather than to the standards of the Chicago L, and thus have what by rapid transit standards are wide curves.

The 7 el is 12 meters wide, and works fine on Queens Boulevard, which is 60 meters from building to building, and poorly on Roosevelt, which is 22. These give an upper and lower bound for street width. The N/W el on Astoria, at 12 meters over a 30-meter street, is also quite bad, though perhaps not as much as the 7 el on Roosevelt. The 1 el in Manhattanville is an imposing steel structure, but its problem is one of topography and height rather than street width, and so it should be put in the category of good els from the perspective of width; this is 12 meters over a 43-meter street. Finally, the Metro-North viaduct in Harlem is 18 meters over a 43-meter street; the area is quite blighted, though it could be a characteristic of the neighborhood more than of the el. Optimistically, it seems that a more modern two-track el, about 9 meters wide (and thus blocking light less than the New York examples regardless of street width), could work over a 30-meter street, such as the Manhattan avenues.

Of course, another issue is the surrounding density. Despite the above calculation I would not want to see new elevated lines on the Manhattan avenues. Partly this is because the population density in Manhattan is so high that the higher cost of a subway is acceptable. But partly it’s because the buildings are tall and would not pair off with the viaduct nicely as they do in Sunnyside. However, it could be a good solution in Queens and the North Bronx, where, additionally, the streets that could take rapid transit are wider than a standard Manhattan avenue.


  1. Andre Lot

    This is not really true:
    “building with wider curve radii is the norm today, and although it increases visual impact and can require more takings, it reduces noise impact, often to practically zero.”

    Any railway traffic will have some noise impact, and noise generation is not only a function of curve radii but also superelevation, wheel technology etc.

    In any case, modern monorails do have a far lower visual impact in the sense that outside stations they produce only 15-25% of the shadowed area of an elevated railway. Take a look at recent projects in Brazil and India…

    • Alon Levy

      Do you have monorail photos? Because the ones I’ve seen are not really that much slimmer than the AirTrain or SkyTrain.

      You’re right that some noise is unavoidable, but the elimination of squeal is still a pretty big thing. In New York, the trains (both subway and commuter) have a distinctive sound, but a decently soundproofed window will block it. I also remember not hearing this sound on trains elsewhere, but I could be wrong.

  2. BBnet3000

    The BART El is fairly low impact (i think), and it gives riders a great view compared to the tunnel sections.

    • Alon Levy

      At least within the trains, BART is extremely noisy. I had to cover my ears when traveling through the Transbay Tube, and the elevated segments are also not very good. On CAHSR Blog, people routinely need to tell the Peninsula NIMBYs that modern mainline rail is quieter.

      Are things different outside the trains?

      • Anon256

        The elevated section between Lake Merritt and Fruitvale is quite audible even two blocks away on International Blvd, despite being essentially straight.

      • Zmapper

        I had to cover my ears going through the Transbay Tube as well. I have been on a few rail systems in the US, and none of them were as noisy as BART was. Is it just the fleet age? Why are their vehicles the nosiest?

        • Alon Levy

          You could get better answers on CAHSR Blog or Caltrain-HSR Compatibility. My understanding is that it’s the infrastructure, not the vehicles: BART is fine at-grade, bad on els and in tunnels, and terrible through the Transbay Tube. So it’s probably the way the tube was constructed that turns it into an echo chamber or something.

          • Danny

            True. Most wheel squealing is remedied by regular greasing of the rails, but with the transbay tube, regular maintenance is not really possible, or at least very costly, as they have to shut down everything. The noise is also compounded in the tube because it is an enclosed area.

  3. Nikko P

    I know your article was very New York oriented but I feel like this has more relevance to places that are considering building rapid transit systems. One of the reasons I heard that Houston built a light rail line instead of a subway is the low water table. If Houston wants an actual rapid transit system, elevated trains might be a good place to start. El lines are cheaper to construct than subways so if a city is looking for a cheaper rapid transit system, a subway is a good place to start. Not that I think that they shouldn’t build light rail, but for the most part I just don’t think light rail is a good stand in for a “mini-metro” system — it should be focused on more localized routes. I could also see this having some relevance in Los Angeles especially with its wide roadways and its massive expanse.

    Just some anecdotal thoughts: when I rode the el in Chicago, one of the things I noticed is that the el was in many places 4 tracks. I thought this would have a big blight for the neighborhoods it passed through. But after looking at the locations on street view ( I found that it wasn’t quite as bad as I thought it would be. When I rode BART to Berkley and the train followed the elevated section on MLK Way I had the same thoughts — this must be an awful eyesore for the neighborhood down below. Again I was wrong ( I’m impressed that it was possible to build a heavy rapid transit system like BART on an elevated line with such little visual impact.

    • betamagellan

      It also helps that Chicago has alleys, so there was often a place to tuck the ‘L’ in routes close to important thoroughfares but without extensive property buys or disruption (which in the days of private mass transit meant more payments to adjacent businesses)–although there’s talk about burying the main line between Belmont and Morse, it’s more due to the extreme difficulty of rebuilding the existing structure (while continuing to run service) than anything else.

      • betamagellan

        Actually, there are a couple of externality-related reasons for rebuilding the north side ‘L’ as a suway–as Alon noted, it’s plauged by tight curves–the proposed subway alignment north of Belmont would not need to make a tight s-curve at Sheridan, which would otherwise need to be fixed with eminent domain and would still require trains to slow down (due to curve fixes and platform consolidation, an all-stop subway trip’s predicted to take less time than an express trip today).

        The subway would also dip under the Brown Line–although the CTA’s wanted a flying junction over the main line for decades (and a serious attempt to get one built in the seventies was shot down by noise concerns), taking the opposite approach is a nice way around that.

        Note, though, that these are attempts to bring a line meant to compete with horsecars to one competitive with automobiles–not only is there enough density to support a subway, but the degree to which the areas abutting the existing line have been built up also make it fiendishly difficult to repair or rebuild.

  4. Joseph E

    I agreen that many cities which have no grade-separated rail could use new elevated trains, at least where the streets are wide enough.

    But with Manhattan’s avenues being 30 meters (100 feet) wide, building-to-building, isn’t there plenty of room for street-level trains, if additional capacity is needed, rather than limiting things to new $1 billion per mile subways?

    Modern light rail can average 18 to 20 mph with stations every 1/2 mile and a max speed of 30 mph (e.g. the Blue Line from East Portland to Gresham in Oregon: and – 8 stations in 4 miles, or the VTA light rail along 1st street: and – 8 stations in 4.5 miles)

    This right-of-way is less than 110 feet at stations, and less than 90 feet between stations, and has room for sidewalks, planting strips, bike lanes, 2 or 3 car lanes, landscaping and 2 tracks. It used to have 2 car lanes and a center turn lane each way, I think? 90 feet; 110 feet with station. A station could fit in 100 feet with only 2 car lanes.

    You could clearly put a surface light rail line on 10 ave, or 2nd Ave in New York, and still have a couple lanes for cars, and plenty of room for sidewalks and a bike path or lane. If the lights are timed for the trains, you could have a 2-car light rail train (=4 car subway train) every 2 minutes per direction at rush hour, and average better than 15 mph. The local subways only average about 18 to 20 mph, due to closely-spaced stations in Manhattan, right?

    Clearly, this would also work for BRT, if New York could get BRT right and put both directions on one street, with a physically separated right-of-way. But tracks and ballast would be harder for taxis to drive on or cops to park on!

    • Anon256

      At-grade transit with aggressive signal priority can work okay on suburban arterials where traffic is light and there are few pedestrians; even then you generally want to grade-separate the busiest intersections. Most users of Manhattan roads are pedestrians, and so the amount of signal priority you can implement is limited, since you need to make sure people who just started crossing have time to cross. Top speed will also have to be limited to avoid killing jaywalkers. An at-grade solution on Manhattan avenues would also have serious conflicts with turning cars at every intersection (there are no left-turn stoplight cycles in Manhattan); any Manhattan intersection would rank among the busiest on most US rail lines. All these factors will lead to average speeds far lower than on the suburban arterial examples you linked.

      Of course, it’s still worth trying to improve bus service in Manhattan, and streetcar lanes might be a worthwhile alternative to bus lanes on some routes. But surface rail in Manhattan is no substitute for subways.

      • Lawrence Velázquez (@larryv)

        “there are no left-turn stoplight cycles in Manhattan”

        If I’m not mistaken, 42nd Street has brief left-turn cycles for westbound traffic at Ninth Avenue and eastbound traffic at Eighth. I can’t think of any others, though.

        • Alon Levy

          There are a few more, Uptown. For examples, Amsterdam and 110th, Columbus and 110th, and Third and 72nd. Those tend to be pretty bad for pedestrian crossings, precisely because of the left-turn lights, which reduce the time pedestrians have a green light.

        • Adirondacker12800

          There was the spaghetti bowl at 14th, Ninth and Hudson. Haven’t been there since it went Yuppie so I don’t know what it’s like since they plopped a park in the middle of it.

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  6. John W

    Another approach that can work nicely is the opposite of building light structures. I’ve always been fascinated by the viaducts with heavy brick arches that are home to all sorts of businesses – the ones that spring readily to mind are the cafes and bars under some of the S-Bahn arches in Berlin at Savignyplatz and at Hackescher Markt station (the round windows are at eye height when you are in the trains).

    The arches below the U6 in Vienna (in the median of the Gürtel, or beltway) similarly have a wide variety of uses, from light industry (auto detailing, say) to nightclubs and a certain fast-food chain. There is more interesting architecture at the stations along the line.

    Ditto London’s Shoreditch and the clubs at Vauxhall. And in my research for images came across this one of the Viaduc des Arts in Paris (no longer used as a railway).

    • Andrew in Ezo

      In Japan these structures and the businesses that occupy them have a name- “gaado shita” or “under the girders”. They are typically small bars and eateries catering mainly to commuters who want a couple of beers and a bite to eat before heading for home.
      At Tokyo’s Yurakucho:

      A more dense arrangement, at Sannomiya, Kobe:

      • Tom West

        UK rail infrastructure ownder network Rail does something similar. Many of the spaces undernearth its viducts in urban areas are leased out on a commerical basis.

    • Lawrence Velázquez (@larryv)

      Off the top of my head, the only instance of this kind of use that I can think of in NYC is underneath the Manhattan end of the Queensboro Bridge. I find it rather disappointing that most of the empty space under the Queens Boulevard viaduct is used for parking.

  7. William Glennon

    IIRC Northeastern University in Boston has its architecture studios, and a campus police station, in the arcades under the Ruggles MBTA stop.

  8. Michael Gross

    If the rails were mag lev there should be a lot less noise, and it would be really high tech and cool!
    Anyone ever hear that the Philadelphia and other Elevated trains were built also due to a series of big snow storms which stopped commerce for prolonged periods?

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