Journey times in Wales have seen an increase following the implementation of a 20mph default speed limit across the country, as indicated by a recent report. The report highlights that since the law came into effect on September 17, 2023, more individuals are adhering to lower speeds while driving. The primary goal of the 20mph speed limit was to diminish the likelihood and severity of road collisions and promote alternative modes of transport like walking, biking, or using scooters, thus contributing to improved mental and physical health.
Transport for Wales conducted the report, which covered the period from September 2023 to April 2024. Key findings included a decrease in vehicle speeds on 20mph main through roads by an average of 4.3mph. Additionally, 58% of vehicles are now travelling at speeds equal to or below 24mph, in contrast to the previous figure of 20%. While average journey times have lengthened on most assessed routes, the majority of these increases did not exceed two minutes. Moreover, there has been a reduction in the variability of journey times on most routes, indicating enhanced journey time reliability.
The report also examined air-quality monitoring, revealing no significant variance in nitrogen dioxide concentrations between 20mph areas and non-20mph areas. However, the study noted that it is premature to evaluate casualty rates, as meaningful comparisons would require three years’ worth of post-implementation collision data. Similarly, the analysis of changes in CO2 emissions will necessitate additional time, while modifications in public attitudes towards 20mph speed limits will be investigated in future research.
Notably, the report highlighted a shift in driving behaviour, with a greater number of people adhering to the 24mph speed limit or below. Across ten monitored areas, the proportion of vehicles travelling between 20 and 24mph rose from 15% to 39%, while those exceeding 24mph decreased from 80% to 43%. Overall, there was a notable increase from 20% to an average of 58% of vehicles travelling at or below 24mph post-implementation.
Furthermore, an analysis of anonymised in-vehicle data collected by Inrix revealed that journey times on 15 selected routes exhibited an increase, with most routes experiencing a rise of less than two minutes. While some routes demonstrated a slight decrease in average journey times, the report emphasized that the journey times were generally more reliable, facilitating better predictability.
In conclusion, the 20mph speed limit has had a noticeable impact on journey times and driving behaviour in Wales, prompting changes in vehicle speeds and increasing adherence to lower speed limits. The findings of this report provide valuable insights into the ongoing effects of the speed limit implementation on road safety and transport patterns in the country.