PicoBlog

A lot of places are building elevated rail these days, something I’m quite a fan of. But with more elevated rail comes more NIMBYism, and with NIMBYism comes bold statements that are backed by tenuous evidence, if any! 

One of the most common comparisons I’ve seen, from Toronto to Montreal and beyond, is the comparison between an elevated rail guideway and an elevated highway — this comparison is a bad one, and I will detail why in this piece. 

Of course, I don’t really believe that most of those comparing elevated rail systems to highways are doing so in good faith, but I do think explaining the specific differences can be useful!

The most obvious and striking difference between elevated rail and an elevated highway is the size. 

As you’ll know if you’ve ever seen a double track rail line up close, the size is not dissimilar from a two lane road, so off the bat, your elevated highway will be substantially larger even if it’s only a bidirectional two lane road. Of course, in practice, many elevated highways have even more lanes and are thus even wider, and the higher the design speed and safety specifications of the highway the wider the individual lanes will be - increasing the structures overall size. 

At the same time, because such a roadway is a large solid structure, it needs more structural support and drainage infrastructure than a railway. The practical impact of this is that you really don’t see elevated highways with single piers supporting them, when this is quite standard for railways. 

Actually getting people onto the elevated structures is another major issue. While with a railway you have relatively simplistic and space efficient stations, with a highway you need ramps, and of course, if you want more safety in speed, you’d need a bigger and bigger ramps — which, by their very nature, take up a lot of space and create a lot of visual barriers. And because elevated highways are usually embedded in an environment of significant car centricity, it’s not uncommon to see wide collector roads or parking underneath them. All of this car infrastructure, not to mention the elevated structure of the highway, serves to create a significant barrier both visually and structurally. By comparison, elevated rail is more minimal and thus tends to be far more “permeable” to human activity. 

Anecdotally, it also generally seems to be the case that elevated highways are much taller given the same general circumstances than elevated rail (probably to deal with ramps and other roadways). In Vancouver, a number of locations has elevated rail, just high enough to clear pedestrian and cycling paths (so low that you can reach up and touch the guideway), which places the infrastructure low enough that even modest trees obscure it. By comparison, significant shadow created by the height and width of a freeway (which also tend to have less of a sculpted profile than rail guideways) makes the surrounding environment feel even more dark and dingy.

One of the most significant externalities one expects from an elevated freeway is road noise, and again on the matter of noise, an elevated rail guideway and a highway aren’t really comparable. 

An issue here is that many people still associate “elevated rail” with the old steel elevated structures of cities like Chicago and New York (and Paris), which are legitimately loud and act a bit like a tuning fork, amplifying the noise of the rumbling trains above. While this style of elevated rail was once prominent, modern elevated rail is overwhelmingly built on concrete structures with things like anti-vibration rail mounting, which go really far to quiet potential noise. I’ll add that the vast majority of elevated railways are electrified, which further reduces noise, not to mention particulates and other types of pollution. Electrification also means quieter trains, and in my experience, living metres from an electric elevated railway, the sound of a train passing was quieter than most trucks (and of course, unlike a highway, the sound is much less a constant drone).

In Toronto, comparisons between elevated rail and highways are particularly useful. The elevated Gardiner expressway on Toronto's waterfront frankly looks decrepit, with chunks of concrete falling off and exposed rebar everywhere. A point to highlight here Is that the loading on an elevated highway is much more intense, and while trains have no issue operating in snowy weather, highways are typically treated with corrosive salt, which leads to them, well, corroding!

There’s also a lot of important history here, particularly related to urban highways. While I did mention the history of elevated rail, I think it’s pretty well established that railways were generally not built with the same disregard for local communities or that highways (especially in the US) have been — this is detailed excellently on this blog. You just don’t hear much of entire communities levelled for railways, which makes sense given the comparative ease of their urban insertion (there are exceptions of course, as seen in Amsterdam). Because of this, I think the comparison is even more inappropriate: railways just haven’t had the same displacing effect. I think recent development trends bear this out, elevated rail is everywhere, but almost no city is building a downtown highway system like seen in a city such as Los Angeles or Atlanta. As I discussed in a previous video, rail corridors certainly can form barriers (the saying “on the wrong side of the tracks” exists for a reason) they are far less negative in their externalities than highways, and they do not require nearly the same space for their right of way, not to speak of massive interchanges. Railways also tend to only become less intrusive with time, as if they run on the surface or in a trench they can be decked over fairly easily, owing to their safety and electric traction.

Suffice to say, all elevated infrastructure is not the same, and as always, comparisons between automobile and transit infrastructure should be made extremely cautiously!

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