On the road again? Monitoring traffic following the easing of lockdown restrictions
On the 16th April, my colleague Dr Jinhyun Hong published a blog examining the impact of lockdown on traffic volumes in Glasgow. With lockdown in Scotland now easing, I decided to revisit the data to see what is happening.
Looking at the news across the UK, there are indications that the easing of lockdown restrictions has led to serious traffic problems. For instance, police were forced to close Falkirk Council’s Roughmute recycling centre two hours after opening it due to traffic building up on roads approaching the site. In Milton Keynes, IKEA was forced to close its car park just two hours after opening due to traffic volumes. Transport Scotland indicated a 60% increase in traffic on Saturday 30th May, compared to the previous Saturday, with traffic at the tourist and leisure hotspot of Loch Lomond up by 200%.
There are various ways to measure traffic volumes. Here, we look at Split Cycle Offset Optimisation Technique (SCOOT) data. The data is gathered from detectors installed at traffic lights. The purpose of the system is to coordinate traffic lights to improve the flow of vehicles. We accessed data on Glasgow’s traffic through an API provided by Glasgow City Council. A total of 41 of the detectors returned complete data for the period we are interested in. The locations are shown below.
We take the average flow measured by the sensors and plot it over time. The interpretation of the flow measure is somewhat complicated. We therefore focus on the relative changes in the average flow. The result aggregated across all detectors is shown below.
The vertical dashed line shows when the lockdown was implemented. We can see that the average traffic flow had already started to decline before the lockdown. This covers the period when people were requested to work from home if possible. The flow is further reduced after the lockdown. Since then, it has remained at this lower level. There is a slight upward trajectory in the flow in the time since the lockdown was introduced, although no dramatic changes. Traffic in Glasgow is still far below where it was in February.
The aggregate pattern hides substantial variation at the different locations where the measurements are taken, which could explain why people may have seen large increases in traffic in their local area. Despite a slight increase, traffic in Glasgow is still far below where it was in February. We will continue to monitor this as public health guidance changes to see whether this is the ‘new normal’ for transport post-lockdown or if we really can’t wait to get on the road again.
Dr David McArthur is the Associate Director for Training and Capacity Building at UBDC and is a Senior Lecturer in Transport Studies at the University of Glasgow.