Citation

Owen R, Smith C, Ursachi G, Fosdick T. Agilysis Limited. Banbury: Agilysis Limited, 2020.

Copyright

(Copyright 2020, Agilysis Limited)

The full document is available online.

Abstract

The period of 'lockdown' during the global COVID-19 pandemic in 2020 saw a rapid decline in traffic flows on all roads. This study uses data from Automated Traffic Counters (ATCs) to investigate the relationship between flow and various measures of vehicle speeds. Data were collected from 91 permanent survey sites in England from a variety of speed limits, for March and April 2020, and processed. A Bayesian approach was taken to modelling the interactions between speed and flow data that produced results demonstrating how speed metrics vary when a reduction in 10,000 vehicles was detected at sites, grouped by speed limit. The observed changes showed some variation by speed limit, with greater decreases on rural single carriageway roads with a 60-mph limit. The model returned results, when transformed for flow, that indicated changes in average speeds of between +0.851 and +2.232 mph. Changes in 85th percentile speeds were higher, increasing by between +0.851 and +3.126 mph. Further analysis of the highest-speed offenders indicated an even larger proportional increase in those travelling at 15mph above the posted speed limit, with higher-speed roads again demonstrating greater shifts. This study is drawing attention to important issues that demand further analysis of additional variables, such as time of data and day of week, and which would be expected to elicit further insight into changes in speeds choice in these extraordinary times.

Keywords: CoViD-19-Road-Traffic