November 2019

Wet & cold, cycling & driving

Our November traffic count provides interesting insights into the impacts of unpleasant weather on road users.

There are many more dry than wet commutes, but the worst does happen sometimes! Of our last 10 mid-November morning peak period traffic counts seven have seen fair or lovely weather and one had only some initial light drizzle.

However, 2019 and 2015 were particularly unpleasant – cold with some rain in 2019 and lots of rain in 2015 – and both days also came right after another wet and unpleasant day which might put people off the next day. Interestingly, the impact of this bad weather on our count results was remarkably similar in both years.

Of course, one cannot be too definite based solely on two counts, but the similarity might make an interesting topic for a research student, particularly as there is little research on this [see below].

This is what we found in both years. [The figures are for 8-9am, counting all vehicles northbound and southbound at Lothian Road and Forrest Road].

  • Total bike numbers fell by only 10%-15% compared to the previous two years (down from 471 in 2018 to 411 in 2019) so the bad weather didn’t seem to have a too great impact
  • City-bound (i.e. northbound) cyclists fell the most, whereas southbound figures were more stable, in fact rising in 2015
  • Perhaps surprisingly, given the weather, car numbers fell – slightly in 2019 and a lot in 2015. However, this fall may not have been weather-related, as car numbers in our city-centre peak period counts have fallen consistently over the years.
  • However, the proportion of cars which were single-occupancy rose – 78.2% in 2019, the highest ever; and 77.8% in 2015, the second highest ever
  • Both bike and car numbers fell most at Lothian Road, but changed less at Forrest Road.

It is interesting to compare the three November counts we have conducted in wet weather, 2019, 2015 and our first ever November count, 2006. Throughout this period (and seemingly independent of the weather) the biggest change has been a consistent and continuing decline in the number of private cars using the city centre in the peak period, whereas cycle use has risen by almost as much as car has fallen.

Data from wet count days in November

Year [data for 8am-9am]200620152019change 2006->2019
Bikes as % of all vehicles 10.5% 14.8% 14.9% n/a
Bike total at all 4 count points335429411+23%
Cars total214117041538-28%
Commercial total (bus, taxi, van etc)717763816+14%

Weather and travel patterns – research

A comprehensive academic paper by Farhana Ahmed [Institute of Transport Studies, Monash University] and others looked into the impact of weather on use of different transport modes, particularly cycling. The authors are interested in possible impacts of future climate change on transport patterns. They report that there has been relatively little research on this topic.

However they mention research by Phung and Rose [in Melbourne, Australia] which suggested that light rain (defined as less than 10 mm over a whole day) deterred 8%-19% of all cyclists while heavier rain deterred 13%-25%, figures compatible with our own data – although another study found a bigger effect.

Further information

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