Trial site selection
In support of the research, an initial analysis by Transport Scotland of the Trunk Road Network identified 660 collisions involving motorcyclists between 2013 and 2017. Using STATS19 data (reported directly from Police attending accident scenes) the work highlighted the North-West region as a priority area for motorcycle casualty reduction.
Following this, BEAR Scotland Ltd (North-West Unit) conducted an in-depth review of collision cluster sites between 2008 and 2017. This work identified sites within a 100m radius where three or more personal injury accidents (PIAs) involving a motorcyclist or pillion had occurred (Figure 2).
Error loading Partial View script (file: ~/Views/MacroPartials/ImageWithoutCrop.cshtml)For more information on the review of collision cluster sites please refer to BEAR (2019, 2021)
With a focus on the A82, A85 and A83, sites were identified in the region ranging from Glencoe, Oban, Inveraray, Loch Lomond and towards Stirling and Crieff (Figure 3).
Error loading Partial View script (file: ~/Views/MacroPartials/ImageWithoutCrop.cshtml)Expert reviews were conducted for each potential site (e.g. complex geometry, tightening or double apexes, descents and inclines prior to bends, bends off fast sections of road) and 22 trial sites were identified and categorised as motorcycle cluster (MCL) sites or PRIME trial (PT) sites.
In addition, BEAR Scotland produced a checklist of site characteristics that each trial site was scored against to identify suitable locations and to also help plan the scheduling of any upgrades required.
The trial sites were spread over a large geographic area of approximately 750 square miles. They represented a range of bends on rural roads with speed limits over 40mph in line with recent casualty statistics (Transport Scotland, 2020).
Two comparison sites were also included in the trials where data were collected but PRIME road markings were not installed. The comparison sites were of a similar standard to the PRIME trial sites. Due to the wide variety of bends and road characteristics on the Trunk Road Network, these comparison sites were not regarded as experimental control conditions (i.e. where identical conditions are usually compared statistically). All trial sites were brought up to similar standards prior to data collection. A summary of the PRIMEs trial sites is presented below.
Table one
| Site | Code | Road | Heading | Bend type |
|---|---|---|---|---|
| Appin House - north | PT-05 | A828 | North | Left-hand |
| Appin House - south | PT-06 | A828 | South | Left-hand |
| Kingshouse - north | PT-07 | A82 | North | Right-hand |
| Kingshouse - south | PT-07 | A82 | South | Left-hand |
| Loch Lubhair - east | PT-04 | A85 | East | Left-hand |
| Loch Lubhair - west | PT-04 | A85 | West | Right-hand |
| Rob Roy's Dip - east 1 | PT-03 | A85 | East | Right-hand |
| Rob Roy's Dip - east 2 | PT-03 | A85 | East | Left-hand |
| Rob Roy's Dip - west 1 | PT-03 | A85 | West | Right-hand |
| Rob Roy's Dip - west 2 | PT-03 | A85 | West | Left-hand |
| Site | Code | Road | Heading | Bend type |
|---|---|---|---|---|
| Taynuilt - west | MCL-04 | A85 | West | Left-hand |
| Inveruglas - south | MCL-11 | A82 | South | Left-hand |
| Runacraig - north | MCL-21 | A84 | North | Left-hand |
| Runacraig - south | MCL-21 | A84 | South | Left-hand |
| Dunira - west | MCL-08 | A85 | West | Left-hand |
| Bonawe - east | MCL-07 | A85 | East | Left-hand |
| Landrick Bends - comparison | n/a | A84 | North | Left-hand |
| Site | Code | Road | Heading | Bend type |
|---|---|---|---|---|
| Dailnamac - east | PT-20 | A85 | East | Left-hand |
| Pulpit Rock - north | PT-11 | A82 | North | Left-hand |
| Butterbridge - north | PT-02 | A83 | North | Left-hand |
| Middle Kames - south | PT-12 | A83 | South | Left-hand |
| Salmon Draft - north | MCL-03 | A83 | North | Left-hand |
| Salmon Draft - south | MCL-03 | A83 | South | Left-hand |
| Carrick - comparison | n/a | A83 | North | Left-hand |
| Dunira - revisited from 2021 | MCL-08 | A85 | West | Left-hand |
| Rob Roy's Dip - revisited from 2020 | PT-03 | A85 | West | Right-hand |
Images from a selection of the trial sites are presented below (Figure 4).
Error loading Partial View script (file: ~/Views/MacroPartials/ImageWithoutCrop.cshtml)These images illustrate some of the left-hand and right-hand bend trials sites where PRIME road markings were installed throughout 2020 to 2022.