Summary results
In total 15,557 motorcycles were observed across all the trial sites. Each of these motorcycles were manually counted and coded in relation to whether they were a lead or following motorcycle (i.e. ‘lead’), solo rider or carrying a pillion (i.e. ‘pillion’), and individual motorcycle or riding as part of a group (i.e. ‘group’). From these 5,680 lead motorcycles were analysed in more detail (Table 4).
Table 4: Showing motorcycle numbers by category recorded throughout the road trials
| Site | Lead | Pillion | Group | Total |
|---|---|---|---|---|
| Landrick | 183 | 53 | 377 | 765 |
| Strathyre | 237 | 55 | 405 | 704 |
| Glenogle | 223 | 60 | 500 | 828 |
| Mid Lix | 222 | 58 | 499 | 792 |
| Dalkenneth | 231 | 36 | 257 | 464 |
| West Lodge | 173 | 29 | 258 | 469 |
| Lawers Lodge - comparison | 272 | 35 | 362 | 630 |
| Total | 1,542 | 326 | 2,658 | 4,652 |
| Overall total | 5,680 | 1,195 | 8,907 | 15,557 |
| Site | Lead | Pillion | Group | Total |
|---|---|---|---|---|
| Strone Hill | 202 | 46 | 320 | 548 |
| Clifton | 277 | 50 | 426 | 696 |
| Ardveich House | 225 | 39 | 264 | 489 |
| Dunira East | 220 | 43 | 247 | 503 |
| Carry over left | 216 | 43 | 247 | 501 |
| Carry over right | 216 | 43 | 247 | 501 |
| Dalchonzie | 263 | 54 | 371 | 623 |
| Tullybannocher - comparison | 224 | 55 | 379 | 623 |
| Total | 2,114 | 428 | 2,945 | 5,196 |
| Site | Lead | Pillion | Group | Total |
|---|---|---|---|---|
| Butterbridge | 258 | 51 | 450 | 541 |
| Butterbride - East | 213 | 45 | 332 | 716 |
| Loch Lubhair - East | 307 | 77 | 528 | 921 |
| Rob Roy's Dip - East 1 | 359 | 73 | 618 | 1,075 |
| Rob Roy's Dip - East 2 | 340 | 76 | 622 | 1,074 |
| Dalkenneth | 304 | 58 | 390 | 677 |
| Tullybannocher - comparison | 243 | 61 | 427 | 705 |
| Total | 2,024 | 441 | 3,367 | 5,709 |
| Site | Lead | Pillion | Group | Total |
|---|---|---|---|---|
| Overall totals | 5,680 | 1,195 | 8,907 | 15,557 |
Motorcycles carrying a passenger/pillion (N=1,195) represented 7.68% of the total sample of motorcycles. The largest proportion of motorcycles were classified as being part of a group (N=8,907), accounting for 57.25% 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, reinforcing the social nature of motorcycling.
Lead motorcycles (N=5,680) accounted for 36.51% of the total sample of motorcycles and were analysed in more detail.
Results from the Phase 2 trial sites are summarised below (Table 5).
Table 5: Showing results for PRIME road marking across the Phase 2 trial sites
Key
* denotes comparison sites
** denotes only incidence of increased braking observed
*** denotes trend in reduced and increased speed observed
Sig denotes statistically significant effects observed
Trend denotes a trend in data
| Site | Speed | Position at PRIME | Position at Apex | Braking | Use of Gateway |
|---|---|---|---|---|---|
| Landrick | Sig | No effect | Sig | No effect | Sig |
| Strathyre | Sig | Sig | No effect | No effect | Sig |
| Glenogle | Sig | Sig | Sig | Sig | Sig |
| Mid Lix | Sig | Sig | Sig | No effect | Sig |
| Dalkenneth | Trend | Trend | Sig | Trend | Sig |
| West Lodge | Sig | Sig | Sig | Sig | Sig |
| Lawers Lodge* | No effect | No effect | No effect | No effect | No effect |
| Site | Speed | Position at PRIME | Position at Apex | Braking | Use of Gateway |
|---|---|---|---|---|---|
| Dalmally | Sig | Sig | Sig | No effect | Sig |
| Strone Hill | Sig | Sig | Sig | No effect | Sig |
| Clifton | Sig | Sig | Sig | No effect | Sig |
| Ardveich House | Sig | Sig | Sig | No effect | Sig |
| Dunira East | Sig | Sig | Trend | No effect | Sig |
| Carry over left | Sig | Trend | No effect | No effect | Trend |
| Carry over right | Sig | Sig | Sig | No effect | Sig |
| Dalchonzie | Trend | No effect | Trend | No effect | Trend |
| Tullybannocher* | No effect | No effect | No effect | No effect | No effect |
| Site | Speed | Position at PRIME | Position at Apex | Braking | Use of Gateway |
|---|---|---|---|---|---|
| Butterbridge | Sig | Sig | No effect | Sig | Sig |
| Butterbridge - East | Trend | Sig | Sig | No effect | Sig |
| Loch Lubhair - East | Sig | Sig | Sig | Sig | Sig |
| Rob Roy's Dip - East 1 | No effect | Sig | Sig | Sig** | Sig |
| Rob Roy's Dip - East 2 | Sig | Sig | Sig | No effect | Sig |
| Dalkenneth | Trend | Trend | Sig | Trend | Sig |
| Tullybannocher* | Trend*** | No effect | No effect | No effect | No effect |
Key findings of the 2023 PRIMEs trials
During the 2023 motorcycle season PRIME road trials were conducted at 6 trial sites and one comparison site in the West Highlands on the A84 and A85 (i.e. Landrick, Strathyre, Glenogle, Mid Lix, Dalkenneth and West Lodge). These trial sites were all left-hand bends.
In total 4,652 motorcycles were manually counted and coded across all the trial sites and from these 1,542 lead motorcycles were analysed in more detail.
Speed was significantly reduced at five trial sites. A trend for reduced speed was observed at another site. Statistically significant effects were observed across four of the trial sites for positive changes in road position at the point of the final PRIME road marking with a trend in positive changes observed at one other. Similarly, for motorcycle position at the apex of the bend, statistically significant effects were observed across five of the six trial sites. This indicated positive changes in road position with motorcyclists taking a wider path around left-hand bends.
While braking was one of the key variables measured in the trials, this did not appear to be a high incidence activity. A significant reduction in braking was observed at two trial sites (Glenogle and West Lodge). A number of trends for reduced braking were observed at other sites.
Across all of the 6 trial sites, significant results were observed for increased use of the PRIMEs. This provided strong evidence that motorcyclists were going ‘through the gap’ at the final gateway marking and therefore in the desired position prior to the bend.
For detailed statistical analyses, please refer to Stedmon, et al, (2025b).
A selection of images illustrate the typical changes in road position due to PRIMEs (Figure 8).
Key findings of the 2024 PRIMEs trials
During the 2024 motorcycle season PRIME road trials were conducted at six trial sites and one comparison site on the A85 (i.e. Dalmally, Strone Hill, Clifton, Ardveich House, Dunira East and Dalchonzie). These trial sites were all right-hand bends.
In total 5,196 motorcycles were manually counted and coded across all the trial sites and from these 2,114 lead motorcycles were analysed in more detail.
Speed was significantly reduced at five trial sites. A trend for reduced speed was observed at another site. A statistically significant effect was observed at five of the trial sites for a positive change in road position at the point of the final PRIME road marking. For motorcycle position at the apex of the bend, a statistically significant effect was observed at four trial sites along with a trend at another two sites. This indicated positive changes in road position with motorcyclists taking a wider path around right-hand bends.
As in 2023, braking was not a high incidence activity with no changes in braking behaviour observed. Across five of the six trial sites, significant results were observed for increased use of the PRIMEs. Trends for increased use of PRIMEs were observed at one other site. This provided strong evidence that motorcyclists were going ‘through the gap’ at the final gateway marking and therefore in the desired position prior to the bend.
At the comparison site no effects were observed, as expected.
During 2024 Transport Scotland supported additional research to investigate the potential for the behaviour change effects of PRIMEs to be carried over to subsequent bends where PRIME markings were not installed. Whilst this was limited to two sites, the results indicated that the significant reductions in speed were sustained at the subsequent bends. These results are discussed further in the discussion section below.
For detailed statistical analyses please refer to Stedmon et al, (2026)
A selection of images illustrate the typical changes in road position due to PRIMEs (Figure 9).
Key findings of the 2025 PRIMEs trials
During the 2025 motorcycle season PRIME road trials were conducted at six trial sites (five of which had been used in previous years) and one comparison site on the A83 and A85 (i.e. Butterbridge, Butterbridge East (new), Loch Lubhair, Rob Roy’s Dip and Dalkenneth).
In total 5,709 motorcycles were manually counted and coded across all the trial sites and from these 2,024 lead motorcycles were analysed in more detail.
Speed was significantly reduced at three trial sites and trends for reduced speed were observed at two other sites. Statistically significant effects were observed for changes in road position at the final PRIME road marking at five sites with a trend observed at one other site. Motorcyclists were riding ‘through the gap’ and maintaining positions closer to the centre of the road. At the apex of the bend, statistically significant effects were observed at five of the six trial sites with motorcyclists taking a wider line around the bend.
Significant reductions in braking were observed at two sites however an increase in braking was observed at another site. As no material changes were made to that trial site it may be anomalous and that there is insufficient data to explore this single episode specifically.
Across the six trial sites there was a significant increase in the use of the final PRIME gateway marking.
At the comparison site, in general the results were as expected. However, a trend was observed for a speed reduction and also an increase when compared to previous datasets.
A selection of images illustrate the typical changes in road position due to PRIMEs (Figure 10).
