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).

Chart showing distribution of injury motorcycle collisions on trunk roads. The highest number of casualties are on the A82 (30) and A85 (19).
Figure 2: Chart showing distribution of motorcycle casualty profile by road number for the North West Region (from BEAR Scotland, 2019)

In order to assist with site identification for Phase 2 of these trials BEAR Scotland Ltd (North-West Unit) refreshed this collision analysis in 2021 (BEAR Scotland, 2021).

With a focus on the A83, A84 and A85, sites were identified in the region ranging from Lochawe, Tyndrum, Inverary towards Stirling and Crieff (Figure 3).

Map of Scotland showing the location of PRIMEs trial sites as described in the text above.
Figure 3: Map showing locations of PRIMEs trial sites 2023 to 2025

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 13 new sites were identified for inclusion in the trials and categorised as motorcycle cluster (MCL) sites or PRIME trial (PT) sites. 12 of these sites were identified for the trials in 2023 and 2024 (6 per year) which followed the approach taken during Phase 1. The research theme in 2025 sought to investigate whether a different design approach could bring about greater reductions in approach speed than previously recorded. For this reason, 5 of the 6 sites utilised in the 2025 trials had previously been used in Phase 1 which also afforded the opportunity to analyse the longer-term effects with comparisons being made with data following their initial installation. One additional new site was also included in 2025.

As in Phase 1, BEAR Scotland produced a checklist of site characteristics that each trial site was scored against to identify suitable locations however the “untreated roads” approach was adopted for Phase 2 with no upgrades being made to the site locations prior to the trials commencing.

The trial sites were spread over a large geographic area and 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 with the same comparison site (Tullybannocher) being used in 2024 and 2025. 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). A summary of the PRIMEs trial sites is presented below (Table 1).

Table 1: 2023 sites
Site Code Road Heading Bend type
Landrick PT21 A84 North Left-hand
Strathyre MCL30 A84 South Left-hand
Glenogle MCL06 A85 South Left-hand
Mid Lix MCL29 A85 North Left-hand
Dalkenneth MCL09 A85 West Left-hand
West Lodge MCL31 A85 East Left-hand
Lawers Lodge - comparison n/a A85 West Left-hand
Table 1: 2024 sites
Site Code Road Heading Bend type
Dalmally MCL34 A85 East Right-hand
Strone Hill MCL36 A85 West Right-hand
Clifton MCL35 A85 East Right-hand
Ardveich House MCL33 A85 West Right-hand
Dunira East MCL32 A85 East Right-hand
Dalchonzie PT22 A85 West Right-hand
Tullybannocher - comparison n/a A85 West Right-hand
Table 1: 2025 sites
Site Code Road Heading Bend type
Butterbridge - revisited from 2022 PT02 A83 North Left-hand
Butterbride - East PT02 A83 East Right-hand
Loch Lubhair - revisited from 2020 PT04 A85 East Left-hand
Rob Roy's Dip - East 1 revisited from 2020 PT03 A85 East Right-hand
Rob Roy's Dip - East 2 revisited from 2020 PT03 A85 East Left-hand
Dalkenneth - revisited from 2023 MCL09 A85 West Left-hand
Tullybannocher - comparison n/a A85 West Right-hand

Images from a selection of the trial sites are presented below (Figure 4).

A selection of four images showing some of the left-hand and right-hand bend trials sites where PRIME road markings were installed throughout 2020 to 2022.. In all of the images a motorcyclist approaches the bend and there is Scottish highland scenery in the background.
Figure 4: These images illustrate some of the left-hand and right-hand bend trials sites where PRIME road markings were installed throughout 2023 to 2025