Factfulness – Congestion

Wouldn’t it be great to have invented this term, but it turns out Hans Rosling beat us to it first with his book Factfulness: Ten Reasons We’re Wrong About the World – and Why Things Are Better Than You Think. 

The book is a very good read and helps to enforce two main points:-

  • We pay more attention to scary things
  • Numbers always look more convincing than they really are

Two important conclusions in the book are that life expectancy in the world really is increasing and that poverty really is decreasing and these are good reasons for celebration. Unfortunately the global temperature is increasing and that remains a reason for grave concern.

Cape Town Congestion

The graph above could be called Congestion: Reasons We’re Right About Cape Town – and Why Things are Just Like You Think.

This graphs shows the traffic congestion index data for Bellville to the CBD in Cape Town, for the period October 2017 to June 2018, for each Tuesday morning, at 05:30am to 09:30am.

Although a picture says a thousand words, three dimensional graphs often need some words to explain them.

The dark blue section at the front shows a low index reading of 25% or so, which means a typical journey of 21km before 05:30am takes about 22 minutes on free flowing roads.

The next blue section shows that by 7:00am, the congestion index is roughly 100%, so the same journey would take 44 minutes. Between 7:30am and 8:30am the index is between 200% and 300% with the journey taking between 60 minutes and 1 hour and 20 minutes.

The graph clearly shows the effects of school holidays, the bus strike in April and a severe accident that took place on June 12th. This is the highest index reading (634%) we have since October 2017 with the journey taking nearly 2 hours and 15 minutes.

This event is called an “outlier” and it is important to take these readings into account so as not to distort the underlying trend in the data. It may be possible to see that trend in October 2018 when we have a years worth of data. Anyone using the roads in Cape Town could make an informed guess.

One of the revealing effects of climate change is the frequency with which extreme weather events occur. The same is likely to be true of congestion in that the frequency of extreme delays on the roads will just keep increasing.

How long can we continue to let this situation deteriorate? Is it already time to consider more strenuous intervention?

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