“Which came first, the chicken or the egg?” is one of those riddles that’s meant to be unsolvable. Which is ridiculous, because the answer is very clearly the egg. There were eggs for millions upon millions of years before there were any chickens. This riddle is stupid.

For a better, more City-Metric-y riddle, consider this:

Which is the DLR closer to? (For my Google maps data: yes, I'm sad) — Dan Simpson (@iamthedans) June 21, 2017

The DLR, for those who haven’t had the pleasure, is the Docklands Light Railway, which connects London’s two financial districts, the City and Canary Wharf, with spurs to Stratford, Greenwich, Woolwich and the Royal Docks.

A map! Image: Wikipedia.

The reason Dan’s question is so hard, and the poll so divided, is because the DLR isn’t really either of those things.

The problem with calling the DLR a tram is that, well, it obviously isn’t a tram. There is a definite overlap between trams and light railways: both involve rolling stock that is both narrower and shorter than normal trains. The systems are so similar, indeed, that units once used on the DLR are now running on the tramways of Essen.

A DLR P89 train in Essen, Germany. Image: Stefan Baguette.

But the word “tram” tends to suggest two specific characteristics: sections where they run on the street, and overhead electrical power. These two things tend to go together for reasons that you’ll spot quickly enough if you imagine the consequences of putting an electrified rail down the middle of a busy urban street.

Edit to add: It's been brought to my attention by our quizmaster extraordinaire Chris Sharp that I over-stated things in that last paragraph:

Many of London's trams didn't use overhead wires. They ran on a third rail set in a conduit between the tracks. — Chris Sharp (@sharpsharp) June 23, 2017

Fair point. Nonetheless: the DLR doesn't run on the street, so is not a tram. Now back to the original article.

The DLR doesn’t have either of these characteristics: it never runs on the street, and its power comes from a third rail. So despite the obvious similarities with, say, the outer sections of Manchester Metrolink, it’s not a tram.

So is it a subway? A form of underground metro?

It has some similarities with that, too: underground sections (in the City, and under the Thames); high capacity compared to many tramways. Also, it appears on the Tube map; until relatively recently, that gave it a status that was denied to Tramlink, down in the southern suburbs.

But – it doesn’t quite fit that either, does it? Most of the DLR is not underground – just five stations out of 45 (Bank, Island Gardens, Cutty Sark, Woolwich Arsenal, Stratford International). In its early years, that number was just one (Bank). In its really early years, it was none.

It’s also, still, a light rail system. And maybe I’m being a stickler, but a proper subway feels like it should have proper trains, not the diddy ones you get in Docklands.

So, no, the DLR is not a tram. Nor is it a subway. It’s an urban light railway, which isn’t really either.

On the upside, it is largely automated. Which means that you can sit up front and pretend to drive the train. The DLR isn’t a tram. It’s not a subway. It’s better than that.

Jonn Elledge is the editor of CityMetric. He is on Twitter as @jonnelledge and also has a Facebook page now for some reason.

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