Executive Summary
This report describes the results of the 2023 Scottish Inspection Panel (SIP) survey. The year‑on‑year SIP surveys provide an assessment of new materials and maintenance techniques used on the trunk road network. The visual assessment survey considers the quality of materials and their installation, and the collection of data permits the benchmarking of newly introduced materials against previously used surface courses. The SIP also supports the development of corrective action plans through the identification of recurring issues.
The 2023 SIP survey was carried out in the week commencing 4 September 2023. The report provides information on the 49 sites visited and presents results on the condition of the materials assessed and any observations made. The main findings are summarised as follows:
- The panel assessed 87% of the five-year-old surfacing sites to be defect free and performing well. The results are seen to corroborate previous SIP findings that TS2010 will provide enhanced durability compared to previously used Clause 942 materials.
- A trend line based on historical SIP data estimates the average service life of TS2010 to be around 20 years.
- Five of the sites performed less well (Good/Moderate) although mitigating circumstances included the presence of cold load ends and an urban area containing a high density of street furniture.
- Two sites marked below Acceptable related to a failure of material on a roundabout, and inadequate foundation support.
- Issues with carriageway markings were noted including debonding and damage associated with marking removal.
The report makes several recommendations including promoting the need to eradicate cold spots; reviewing the performance of surfacing on roundabouts; ensuring adequate support is provided at the design and maintenance stage; and appraising the performance of carriageway markings.
Contact name: Michael McHale
Contact details: Michael.McHale@wsp.com