Whether the Weather

Are you a weather stoic, giving two fingers to whatever the clouds might throw at you, or are you a weather syncophant, letting a little rain pressure you into changing your plans? As the clocks change, are you pleased to have the additional daylight for the morning commute, for the accidents purportedly prevented, for the comfort of walking your children to school? Or do you worry about the dark trip home and choose to hibernate when possible?

The impact of weather on travel choices is a subject discussed and considered by many transport planners. Researchers have subjected various hypotheses to empirical testing. One literature review of the subject compiled a list of 54 articles reporting research on how normal weather variations affect normal travel patterns, and this is cited as only a sample of the total (Bocker et al 2013).

Many of these studies test commonly-held hypotheses using real-time weather measurements, empirical transport data and statistical modelling. For example, everyone has heard of the fair weather cyclist and it would surprise no one to be told there are more cyclists in the summer in temperate climates. Thus, researchers in cities from Montreal to Melbourne and San Francisco to Singapore have used cyclist counts, travel diaries and route-side surveys to investigate whether and by how much precipitation, high or low temperatures or wind affect the amount of cycling for utility or leisure. Their results indicate that the weather does have an impact, particularly rain, and to a lesser extent, temperature and strong winds. Not that it’s completely straightforward. The studies differ on whether the precipitation effects take hold at the first sign of drizzle or only in heavier downpours, and whilst cyclists do prefer warmer weather, it’s only up to a point. Numbers decline again when it’s too warm or humid – a trend that has significant consequences in hotter climates.

Another theme of research focuses on changes in car traffic in different types of weather. Unsurprisingly, snow can reduce traffic substantially. The impact of rain is more nuanced. Some studies show a decrease in traffic, whilst some show an increase and more specifically a modal switch from walking and cycling to car travel. Few cancel their trips entirely if they are commuting or on business, but changing the timing of a trip is an option more often considered. Perhaps this is due to the commonly-held and well-substantiated belief that traffic speeds are slower and congestion greater in wet weather.

Indeed, there is another suite of studies on the performance of roads in wetter weather and the effectiveness of weather-responsive traffic management, although such articles were outside the scope of the aforementioned literature review, specifically excluded due to the focus on “infrastructure maintenance, accident rates and… performance” rather than travel behaviour.

Also excluded were extreme weather scenarios, as the purpose was to assess the studies of everyday events. Yet heavy rain, heatwaves, snow and gales can so affect infrastructure that travel choices are reduced – and some are removed altogether…

Thus, as winter approaches, how will you choose to travel no matter the weather or no matter whether the weather takes some choices away?

Böcker,  L.; Dijst,  M. and  Prillwitz,  J. (2013) Impact of Everyday Weather on Individual Daily Travel Behaviours in Perspective: A Literature Review. Transport Reviews: A Transnational Transdisciplinary Journal. 33:1. pp 71-91.

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