Summary report of PRIME road trials 2020 – 2022

Author/researcher: Professor Alex Stedmon

Date of Publication: January 2023

Uploaded to Knowledge Centre: 17 October 2023

Innovative road markings for motorcyclists, designed as Perceptual Rider Information for Maximising Expertise and Enjoyment (PRIMEs) were installed on the approach to demanding bends at 22 trial sites and two comparison sites across the West Highlands of Scotland. These road markings were presented as a series of ‘gateways’ to encourage safer riding. All sites were of similar standards in relation to road surface and environment. Video data were collected to measure motorcycle speed, lateral position, braking and use of the road markings, before and after the PRIME road markings were installed.

A total of 32,213 motorcyclists were observed. Across the trial sites, statistically significant reductions in speed were observed at 10 trial sites. Significant changes in lateral position were observed at the final PRIME gateway marking at 15 trial sites with motorcyclists riding in better positions on approach to the bend. Statistically significant changes in lateral position at the apex of the bend were observed at 13 trial sites. Statistically significant reductions in braking were observed at nine trial sites. There were statistically significant increases in the use of PRIME road markings across 18 of the 22 trial sites.

No statistically significant effects were observed at the comparison sites. These findings are discussed in relation to sustained effects, the ‘Road Safety Framework to 2030’ and the ‘Safe System’ approach to reducing motorcycle casualties.


  • This research is a world-first and the largest road trial investigation of PRIME road markings involving 32,213 motorcyclists
  • Unique PRIME road markings for motorcyclists produced statistically significant positive behavioural changes in speed, lateral lane position and braking at sites around the Scottish Highlands
  • This in-depth study identifies important behavioural factors that support Transport Scotland’s ‘Road Safety Framework to 2030’ and the ‘Safe System’ approach to motorcycle casualty reduction

Access the report via the Transport Scotland website: