Of electric bikes and bionic duckweed

Why the cities of the future will still need mass transit.

I’d been avoiding it – not because I disapprove of the tech, you understand, purely because the old fashioned way is how I get much of my exercise – so doing it this way felt like cheating. But one evening last week I was late for a fashionable media soiree of the sort you probably assume I attend all the time, and the only bike available in my nearest bike stand was an electric one, and it was threatening to rain, and so I just thought: why not? I should probably try one eventually, for research purposes, if nothing else. So, from my home in the East End to a pub off Tottenham Court Road, I rode my first electric bike.

And would you believe it? All the things people have been saying about them are right: it really did feel like a qualitatively different experience from riding a boring, old-fashioned non-electric bike. The pedal-assist makes both acceleration and hills much less effort, and makes it easier to keep up with the traffic. I managed a journey that’d normally take me 35 minutes in something south of 25, quicker than the tube – and I still got off feeling like I’d had at least a bit of a workout.

There are two contradictory theories doing the rounds about e-bikes at the moment. One has it that, as a relatively green alternative to cars and motorbikes, faster and easier than regular bikes, they’re the urban transport mode of the future – that they could even, whisper it, render investment in old fashioned things like trams look pretty silly. The other is that they’re the latest example of what the Royal Statistical Society’s Stian Westlake has termed “bionic duckweed”:

…a sort of unobtainium that renders investment in present-day technologies pointless, unimaginative, and worst of all On The Wrong Side Of History. “Don’t invest in what can be done today, because once bionic duckweed is invented it’ll all be obsolete.”

Why “bionic duckweed”? Because of a Blair-era government white paper, which warned against spending money electrifying railway lines on the grounds that the trains of the future would probably be powered by hydrogen produced by the eponymous plantlife. The point of bionic duckweed is not merely that it may never happen (though it probably won’t): it’s that it tends to be promoted largely by people whose interest is mainly in stopping us from doing something else. 

So, would building the long-awaited tram network for Leeds, say, really be a waste of money because we’re all going to be zipping around the place on electric bikes anyway? Or is this merely something which people who, for whatever reason, never much liked spending public money on public transport anyway say, in roughly the same manner which some people, wrongly, claim the not-actually-existing hyperloop renders all investment in high speed rail pointless?

I have my suspicions. But definitively demonstrating this one way or the other has proved surprisingly, and annoyingly, difficult. 

To start us off, here’s a chart, from TUMI, the Transformative Urban Mobility Initiative, comparing the passenger capacity of different transport modes. What we’re looking at here is the number of people who can be moved in a single corridor, 3.5 metres wide, every hour.

This may well remind you of one of those pictures comparing the amount of road space you’d need to transport a given number of people. It shows, pretty clearly, that private cars are incredibly inefficient uses of urban space; buses are a bit better, and bikes and walking better still. If you really want to use scarce space effectively, though, you’re better off turning to trains or buses that act like trains.¹ You can find similar graphics all over the internet. Here’s another.

You may have noticed that something’s missing, however. All these graphics tell us is throughput – how many people you can get through a given space in a given time. Taken on face value, that would suggest a transport network based entirely on walking is a more efficient use of space than one involving buses, which clearly isn’t true. I think we can assume that something these graphics don’t take into account is speed – how quickly those people might actually reach their destination.²

If we throw that into the mix, what’d that do to the figures? My suspicion, based on the fact that nobody seems to try, is that it’s extremely difficult to make direct comparisons. This graph – which relates to Timisoara, a Romanian city with buses and trams but not full scale metros – suggests one reason why:

Branea/Gaman/Badescu/creative commons. 

The reason the public transport line starts at a different point on the y-axis is that you have to wait for a bus or a tram, in a way you don’t for your car/bike/feet. In other words, there are too many variables, making direct comparisons of the type in those earlier graphics impossible. 

That said, public transport in Timisoara clearly does move faster than most other modes of transport. This makes intuitive sense: you can literally see it, when a train goes past, and it’s a big reason why cities build railway lines in the first place. 

There is another reason to think that mass transit will always be an important part of the mix in any sizable city, no matter what the bionic duckweed fanatics tell us. Jarrett Walker, an American transit consultant, has argued that the fundamental thing a lot of whizzy new transport technologies forget about is basic geometry:

Any “small vehicles replacing big vehicles” solution increases the total number of vehicles on the road at any time... Increasing [vehicle miles travelled] means that you are taking more space to move the same number of people. This may be fine in low-density and rural areas, where there’s lots of space per person. But a city, by definition, has little space per person, so the efficient use of space is the core problem of urban transportation.”

Walker was writing about chief twit Elon Musk’s plan to replace buses with Personal Rapid Transit, a largely theoretical but space-hungry mode of transport where we’d each get our own pod like we’re in Futurama. But this surely applies to electric bikes, too. Sure, they take up less space than a car – but it still takes more space to move 100 people by bike than by the Piccadilly line. If you need to move vast numbers of people through the same space at the same time, then mass transit – as the name suggests – should probably stay part of the mix. 

So can e-bikes really render public transport redundant? My suspicion is that it’s going to depend on the city. Above a certain size, public transport will almost certainly be quicker, and certainly more efficient in terms of space. More than that, though, in some climates, a warm bus is always going to win out over being exposed to the elements on a bike, e- or otherwise.

So no, electric bikes won’t magically render all existing public transport tech obsolete. My guess is: a city like Leeds still needs its tram. 

Map of the week

This week, some fabulous data visualisation, courtesy of a Parisian named Benjamin Td: an isochrone map, showing how far you can get in five hours from any point in Europe.

Note the blobs around places with high speed trains.

It might be slightly misleading – Benjamin has made the “assumption” that all the connections are 20 minutes, which, hmmm (“Since there is no guarantee that trains will connect perfectly, the map tends to be overly optimistic,” he admits). But it does highlight one of my favourite facts about this continent’s infrastructure: that, even decades after the Berlin Wall came down, it’s still a lot quicker to get around the west than the east.

I’ve had to keep screenshots to a minimum to ensure this newsletter doesn’t get too big for the email filters: this animation does a better job of selling the map to you than I’m going to be able to here. Or, even better, you could play with it yourself.

Self-promotion corner

This is an extract from the archive of The Newsletter of (Not Quite) Everything, a newsletter (obviously) sent every Wednesday around 4pm. In this week’s edition I wrote about how the home of London’s government tells a story of national decline; why the poet Homer couldn’t see the colour blue; and the curse of protected views.

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1. Full disclosure: I can’t for the life of me work out what this graphic means by single or double land BRT [Bus rapid transit], or why the latter would have nearly five times the capacity. Answers on a postcard.

2. I spent an hour screwing up my face, trying to work out how to take that into account using tricks like dimensional analysis which I half-remembered from my A-Levels. Then I remembered I’d decided to do an English degree and gave up.