False Equivalence and Our Roads

8. October 2018 19:23 by olops in Cycling  //  Tags: , ,   //   Comments (0)

I am fed up of coming across examples of false equivalence on social media, so eventually I wrote this ...

Consider the relative danger a cyclist poses to other road users compared to the driver of a car. 

A driver is sitting in 2000kgs of car, A heavy bike is 15kgs and you can add 80kgs of human to that if you are me;) 95kgs. Let's round it up to 100kgs. On this basis you might argue that a driver provides 20x more danger to other road users than a bike. Of course the difference is much greater than this as the car can travel much faster than the bike.

Consider the fairly extreme, but not uncommon, case of a car overtaking a cyclist at 50mph on a road where the cyclist is travelling at 15mph. Where are we up to on the relative danger caused by each individual now? 50x more danger? More? Well, let's try and work it out based on their kinetic energy: 

Driver: 0.5 * 2000 * 50*50 = 2,500,000

Cyclist: 0.5 * 90 * 15 *15 = 10,125

Noting that I'm not worrying too much here about using the correct units (feel free to convert yourselves) to ascertain exactly the correct energy value in joules as I am only interested in relative figures here.

Divide one by the other and you get the relative kinetic energies one to the other and I'll initially posit that this equates to the of relative danger the driver of the car poses to other road users in this scenario: 246.91.

So the driver of the car provides approximately 250 more danger than the cyclist. Aside: see that speed being squared as part of the equation. This is why sticking to speed limits and the roll out of 20 limits to all urban areas is so important.

But we've not finished. There is another angle - the driver is in a metal box while the cyclist is almost completely exposed. How does this affect the relative danger posed by each. Well, just from a common sense point of view take this example - a driver in a car hits a cyclist on a bike head on at the aforementioned speeds? You multiple that relative danger by multiple factors of 10?

Next, think about a 10tonne lorry …

Finally, think about the relative danger a cyclist and a driver cause towards a pedestrian crossing the road. We can approximate the pedestrian's kinetic energy 0.5 * 75  * 5 * 5= 938 given the relative dangers of each:

Pedestrian 1

Cyclist 11

Driver 2665


Hmm ...


Equating the danger to other road users caused by cyclists to that caused by drivers is false equivalence. It is wrong. It is dangerous. It is ignorant. Don't do it.


We need to focus road safety improvements on those that cause the most danger. These are the bad drivers. There is no point wasting resources on cyclists who cause minimal danger to other road users.


A Too many drivers run red lights.

B But I see lots of cyclists running red lights.

This is false equivalence. B is ignorant. Don't be like B.


A Too many drivers pass cyclists dangerously, not giving them enough room. 

B But what about the cyclists who go on the pavement, eh?

This is false equivalence and whataboutery. B is ignorant. Don't be like B.



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About the author

I am Dr Christopher Sully (MCPD, MCSD) and I am a Cardiff, UK based IT Consultant/ Developer and have been involved in the industry since 1996 though I started programming considerably earlier than that. During the intervening period I've worked mainly on web application projects utilising Microsoft products and technologies: principally ASP.NET and SQL Server and working on all phases of the project lifecycle. If you might like to utilise some of the aforementioned experience I would strongly recommend that you contact me. I am also trying to improve my Welsh so am likely to blog about this as well as IT matters.

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