Executive Summary

Around the world, across motorised vehicles, motorcycles represent the most vulnerable road users. Typically, motorcyclists are around 51 times more likely to be killed on the road than car drivers (Crundall, Stedmon, Crundall, and Saikayasit, 2014; Department for Transport, 2019; Transport Scotland, 2020).

Within Great Britain, motorcyclists typically represent less than 1% of the total vehicle miles on roads, but account for 21% of all road fatalities (Department for Transport, 2019). In Scotland, motorcyclists represent only 2.2% of all registered vehicles but account for 14% of all Killed or Seriously Injured (KSI) casualties (Transport Scotland, 2020).

Latest figures for Scotland indicate that there were 446 motorcycle casualties in 2024. This represented a decrease of 7% of whom 274 (61%) suffered serious injuries and 31 died. However, this was an increase of four fatalities from 2023 (Transport Scotland 2025). Within GB there were 340 motorcycle fatalities in 2024 compared with 315 in 2023, an increase of 25 (Department for Transport, 2025).

PRIMEs for motorcycle casualty reduction

PRIMEs provide a tool for riders to adapt their behaviour on approach to a potential hazard while optimising their expertise and enjoyment and remaining safe on the road. Phase 1 of the trials represented a 3-year investigation (2020 to 2022) of ‘Perceptual Rider Information for Maximising Expertise and Enjoyment’ (PRIMEs) on Scotland’s Trunk Road Network. Throughout Phase 1 the trial sites had been brought up to the highest standard through road engineering works. This provided an opportunity to investigate PRIMEs without extraneous variables affecting rider behaviour. The results demonstrated that the ‘PRIME’ road markings produced positive behaviour change across a range of measures that underpin keeping roads users in Scotland safe.

Following a successful funding application for Phase 2 of the research, specific activities have been conducted through 2023 to 2025 to increase the impact of the findings and expand the knowledge base above and beyond Phase 1. As in Phase 1, Phase 2 has focused on the safe navigation of bends. This remains a critical activity for motorcycle safety where motorcyclists have to make sure that: speed is suitable for the conditions; position is optimised for entering and travelling through the bend; and braking is minimised whilst travelling around the bend. With the need to reduce motorcycle casualty rates on the UK’s roads remaining a key focus for road safety, Phase 2 provided a unique opportunity to expand the scientific knowledge base of PRIMEs into critical areas that were not possible in Phase 1.

The key aim of this phase of the research has been to conduct further research to consolidate our understanding of the benefits or drawbacks of installing PRIMEs based on trial site characteristics. This has been addressed through practical objectives to:

Install and evaluate PRIMEs across 18 trial sites and expand the PRIMEs dataset to 40 trial sites and 50,000 motorcycles – by the end of 2025, data were collected at 18 trial sites (13 new trial sites plus 5 sites used in previous years’ research) and two comparison sites. In total, 47,770 motorcycles were observed by the end of Phase 2. While not reaching 50,000 motorcycles this reflects the opportunistic nature of the sample.

Address specific research questions for: untreated roads, right-hand bends, and further reductions in speed – each year during Phase 2 these specific research questions were investigated. These have been detailed in each year’s technical reports and integrated in this summary report.

Conduct a meta-analysis to provide guidance on identifying sites where PRIMEs might be beneficial or not – as part of earlier Phase 2 work (outside of RST funding) with the development of the Installation Toolkit, a thematic analysis of bend characteristics was conducted to provide insights into which bends might benefit the most from PRIMEs and also those that may not. The findings from Phase 2 will be considered in any update of the Installation Toolkit so that practitioners can make informed decisions about installing PRIMEs at their own proposed locations

Use Human Factors participatory methods to promote wider acceptance of PRIMEs by motorcyclists and other road users – this has been developed through informal outreach activities and also through public engagement activities throughout Phase 2

Feedback and disseminate results to Government ministers, road safety stakeholders, academia and riders themselves – Project PRIME has been able to disseminate research findings throughout Phase 2 to a variety of professional interest and stakeholder audiences

Provide substantive evidence beyond Phase 1 of site characteristics and benefits of PRIMEs at different locations – through the expanded scientific knowledge for PRIMEs generated through Phase 1 and Phase 2, conference/stakeholder presentations and scientific journal papers, there is now a substantial peer-reviewed and academically accepted basis to the science behind PRIMEs.

Unique research in the West Highlands

Based on formal reviews and analyses of collision data, 13 new trial sites were identified in the West Highlands ranging from Glencoe, Oban, Inveraray, Loch Lomond and towards Stirling and Crieff. Five trial sites were revisited from previous years’ research. Two new comparison sites were also included where data were collected but PRIME road markings were not installed. At one comparison site data were collected over two different years to investigate behavioural consistency.

This research followed a conventional ‘pre- and post-intervention’ method, where baseline data were compared with data collected once the PRIME road markings had been installed. Data were captured at each site using small and inconspicuous roadside video cameras to analyse speed, lateral position, braking behaviour and use of the PRIME road markings.

The PRIME road markings were installed using 3M^TM Stamark^TM High Performance permanent tape. They underwent a range of design specification, user acceptance, evaluation, and non-prescribed road sign application activities prior to being installed on public roads for the trials. Independent road safety audits were also conducted before and after the PRIME road markings were installed in accordance with best practice.

Over 47,500 motorcycles observed

In Phase 2 a further 15,557 motorcycles were manually counted and coded across all the trial sites (a total of 47,770 when combined with the 32,213 analysed in Phase 1). Motorcycles carrying a passenger/pillion (N=1,634) represented 10.5% of the total sample of motorcycles. The largest proportion of motorcycles were classified as being part of a group (N=8,970), accounting for 57.65% of the total sample of motorcycles. This would indicate that while motorcyclists did not generally carry a passenger/pillion they were likely to be riding with other motorcyclists, further reinforcing the social nature of motorcycling.

Statistically significant changes in rider behaviour

Lead motorcycles (N=5,680) accounted for 36.51% of the total sample of motorcycles and were analysed in more detail. Results across the 18 trial sites are summarised below:

Lateral position at the final PRIME road marking – statistically significant changes in lateral position were observed at 14 trial sites with motorcyclists riding in better positions on approach to the bend. Trends were observed at two other sites.

Lateral position at the apex of the bend – statistically significant changes in lateral position were observed at 14 trial sites. A trend was observed at two other sites.

Braking behaviour – statistically significant reductions in braking were observed at 9 trial sites. Trends were observed at two other sites.

Use of the PRIME road markings – statistically significant increases in the use of PRIMEs were observed at 17 trial sites. Trends were observed at one other site.

At the comparison sites a trend was observed in the data for one site in between the 2024 Baseline and 2025 PRIME data. Overall, these results indicated that while minor speed differences were observed at this comparison site they were not statistically significant and the results can be regarded as generally consistent across 2024 and 2025.

Long-term effects of PRIMEs

Transport Scotland funded additional research to investigate rider behaviour changes over the longer term. By revisiting previous trial sites there was an opportunity to investigate long-term behaviour change by comparing results from 2025 with previous years. It was therefore possible to compare behaviour across 5-year, 3-year and 2-year intervals. Long-term behaviour change was evident when results were compared across different years. From the five trial sites that were revisited, four demonstrated long-term effects for position at the final PRIMEs marking and three sites demonstrated long-term effects for position at the apex. There was also a long-term pattern of reduced braking at one site and across all five sites there was a long-term increase in the use of the gateways. To find that behaviour remains stable at the comparison sites and that long-term behaviour change exists up to 5-years at some sites provides valuable evidence that PRIMEs can have a long-lasting effect on rider behaviour.

Largest motorcycle study of its kind

As far as the research consortium are aware, this is the most in-depth investigation of motorcycle rider behaviour to date, not just in relation to the installation of PRIMEs but also in examining rider behaviour through the baseline data collected. With a total of 47,770 motorcycles manually counted, coded and analysed, the results provide substantial evidence that PRIME road markings had strong, sustained, and long-term effects on speed, position and braking.

However, it is important to highlight that braking increased at one site. In addition, while the collision data for the entire trial period are still being collated, early signs point to a reduction in motorcycle injury collisions where PRIMEs have been installed.

Project dissemination and recognition

To date, the research has been published as five scientific papers for the world-leading journal ‘Transportation Research Part F: Behaviour and Psychology’ (Stedmon et al, 2021, 2022), ‘Ergonomics’ (Stedmon et al, 2024a), ‘Human Factors’ (Stedmon et al, 2025b), and ‘Advances in Transportation Studies: An International Journal’ (Stedmon et al, 2026). Findings have also been published in the proceedings of the Chartered Institute of Ergonomics and Human Factors’ Annual Conference (Stedmon et al, 2023, 2024b, 2025a). This demonstrates that the research has been peer-reviewed to the highest standard by the international academic community. Project PRIME was also recognised by a number of awards during 2023 with the Chartered Institution of Highways and Transportation (CIHT) Awards commendations: highly commended for ‘Road Safety Award’ and commended for ‘Research Initiative of the Year’. At the Institute of Highway Engineers (IHE) Highways Awards Project PRIME won the ‘Road Safety Scheme of the Year’ and the ‘Judges Special Merit Award’. Project PRIME was also awarded the ‘Prince Michael International Road Safety Award’. At the 2025 Chartered Institute of Ergonomics and Human Factors’ Annual Conference, Project PRIME won the ‘Best Paper’ award (Stedmon et al, 2025a).

Project PRIME toolkit and impact

Alongside the further road trials conducted during Phase 2 the project consortium have also developed an Installation Toolkit for Project PRIME. This toolkit provides summary details of the process adopted during Phase 1 of Project PRIME and includes information on site identification, design and installation considerations together with effectiveness in the context of bend characteristics. The Installation Toolkit has been developed and published separately by Transport Scotland and is available here. It is intended to assist road authorities in replicating the approach taken in the Project PRIME trials.

In 2025 the Welsh Government authorised four pilot sites of PRIMEs in Wales. The Project PRIME team have been approached by National Highways to assist with an application to the UK Department for Transport (DfT) for PRIME trials in Derbyshire and other local authorities have approached DfT. There is also interest from a number of local authorities in Scotland who are planning to install PRIMEs in their areas during 2026.

In January 2026 Project PRIME featured in the safe infrastructure theme of the DfT Road Safety Strategy to 2035. The Strategy acknowledges the positive results in Scotland and confirms that the UK Government is supporting PRIME pilot trials in new regions (Department for Transport, 2026).

Transport Scotland pioneering world-leading and world-class research

This is a project which the Scottish Government and parliamentary ministers are aware of. Reaching out to ministers of transport and tourism, this work promotes a key message in keeping motorcyclists safe in Scotland and reducing casualties, with knowledge that can be taken around the world to showcase Scotland as a pioneer in this work. Parliamentary briefings, in turn, provide further mainstream media opportunities to publicise the work and promote the Road Safety Trust’s support and potential for future research funding along with wider research impact.

This research underpins the development of bespoke motorcycle road safety measures that should act as an important step in reducing motorcyclist road casualties. By demonstrating the positive influence of PRIMEs on rider behaviour and rider safety, this work showcases Transport Scotland and the Road Safety Trust as leaders in this initiative for the UK and the world.

Purpose

This report provides a summary of the research findings. For practitioners looking to install PRIMEs then the installation toolkit is recommended. For further research findings please refer to the conference and journal papers included in the reference section.

Funding acknowledgement

The research element of Phase 2 of Project PRIME has been primarily funded by the Road Safety Trust (ref RST:303_0_23) with additional work elements funded directly by Transport Scotland.