It’s that time of year again, isn't it? The crisp autumn air is settling in, leaves are turning those glorious shades of red and gold, and somewhere in the back of our minds, there's a gentle nudge: the clocks are about to change. Specifically, they're going to spring back, marking the end of British Summer Time (BST) and ushering us back into the familiar embrace of Greenwich Mean Time (GMT) for the winter months.
This biannual ritual, a practice shared by many countries across North America and Europe, is essentially a temporary adoption of a different time zone for the summer. In the UK, we push our clocks forward by an hour at 1 am GMT on the last Sunday in March, making those spring mornings a little darker but the evenings wonderfully lighter. Then, come the last Sunday in October, we reverse the process, turning the clocks back at 1 am GMT. It’s a system that’s been synchronised across the European Union since 1995, aiming for a consistent approach.
But have you ever stopped to think about what this seemingly simple shift actually does? Beyond the obvious extra hour in bed in autumn or the slightly groggy start to spring, there are deeper implications. One area that’s been a subject of considerable debate is road safety.
It’s a fascinating thought, isn't it? How can a simple flick of a clock hand impact whether someone gets into a collision? Well, the core idea is that changing the clocks alters daylight hours. When we move to BST, mornings become darker, and evenings lighter. Conversely, when we revert to GMT, mornings get lighter, and evenings darker. This shift, particularly the darker evenings in autumn and winter, can have a tangible effect on visibility for drivers, cyclists, and pedestrians.
Looking at data from the Department for Transport, specifically six years' worth of STATS19 accident information from 2012 to 2017, provides some intriguing insights. Researchers compared collision data for the two-week periods immediately before and after each clock change. It’s a meticulous process, carefully excluding those odd hours around the change itself where the time is either skipped or repeated, to ensure a clear comparison.
And what did they find? Well, it’s not entirely straightforward. In spring, when the clocks go forward, there’s actually a slight reduction in personal injury collisions – around 1.5% fewer per year in the fortnight following the change. That’s about 74 fewer collisions annually. This might be attributed to the lighter evenings, potentially improving visibility for commuters.
However, the autumn clock change tells a different story. The fortnight after the clocks go backwards, marking the end of BST, sees a noticeable increase in collisions. On average, there are an additional 278 personal injury collisions per year, a jump of about 5.1%. This surge is more than enough to outweigh the spring decrease, leading to an overall annual average increase of 2.0% in collisions in the two weeks following either clock change.
Interestingly, the analysis also delved into factors like latitude, accident severity, and weather. It makes sense that the further north you are, the more pronounced the impact of darker mornings or evenings might be. While the data didn't account for traffic levels or school holidays, the consistent pattern of increased collisions in the autumn after the clocks go back is a significant finding. It highlights how our daily routines, dictated by the clock, can have real-world consequences on our safety on the roads.
