Background

Client +Location: Malcolm Hughes was commissioned by The City of Edinburgh Council to deliver a specialist Ground Penetrating Radar (GPR) survey along Corstorphine Road, Edinburgh, providing accurate, non-intrusive insight into subsurface conditions. The Council selected Malcolm Hughes through the relevant framework, recognising our strong track record in delivering high-quality Underground Utility Mapping services within complex, safety-critical environments.

This work forms part of Edinburgh City Council’s significant long-term investment in improving the condition of the city’s roads. Increased funding has been committed to accelerate resurfacing programmes and deliver lasting benefits for road users across the city. For the second consecutive year, an additional £12.5 million has been allocated to roads and infrastructure, with the majority directed towards improving carriageways and footways.

Beneath these streets lies more than modern infrastructure. Edinburgh’s roads also conceal the legacy of a historic tram network that operated for over 85 years, evolving from horse-drawn carriages into one of the most advanced electric systems of its time before being dismantled in the mid-20th century.

A brief timeline of Edinburgh’s original tram system:

• 1871–1907 | Horse-drawn trams – Edinburgh’s first tram services launched, connecting key routes such as Haymarket to Leith.

• 1888–1923 | Cable-hauled trams – Introduced to tackle the city’s steep gradients, creating one of the largest cable systems in the world.

• 1922–1956 | Electric tram network – Full electrification delivered peak efficiency, carrying almost 200 million passengers a year across 47 miles of track.

• 1956 | Closure – Despite widespread use, the network was decommissioned in favour of buses, leaving much of the infrastructure buried beneath today’s roads.

Challenges 

The requirement for this survey arose after previous resurfacing operations encountered this historic buried infrastructure. These unknown features had caused significant damage to resurfacing plant machinery, resulting in operational delays and substantial associated costs for our client. To prevent further risk, our client required a robust, high-resolution survey to support:

• Pavement condition analysis
• Accurate buried service location
• Hazard detection including tram lines, buried ironworks, and historic infrastructure

Our non-intrusive approach using a Vehicle Mounted GPR ensured the client could progress with resurfacing works with full confidence in the subsurface environment.

The project presented several critical challenges:

• Unknown Buried Obstructions: Previous phases of work revealed multiple hidden features beneath the carriageway, posing a clear safety and operational risk.
• Damage to Plant: These obstructions had already caused severe harm to resurfacing equipment: an issue the client could not risk repeating.
• High Financial Impact: Unplanned downtime, plant repairs, and delays had generated significant costs, increasing the need for reliable, pre-construction intelligence.
• Requirement to Minimise Disruption: Given the route's prominence, the survey needed to be conducted overnight using vehicle mounted technology to ensure traffic impact remained negligible.

Tools and Technology

To meet these challenges, Malcolm Hughes deployed our advanced Vehicle Mounted GPR system, utilising the Kontur Stepped Frequency Continuous Wave GPR technology. This system is specifically designed for rapid, high-resolution acquisition over long linear routes, making it ideal for strategic highway surveys.

The data collected provided detailed subsurface insight, including:

• Pavement layer thicknesses and construction profiling
• Identification and positioning of buried utilities and services
• Detection of hazards such as tram lines, cats' eyes, historic ironworks, and other metallic or non-metallic obstructions

This approach aligns with our industry-leading capability in Underground Utility Mapping, delivering accurate, PAS 128-aligned information where required.

Solutions Devised  

Our solution was built around a fully non-intrusive, high-efficiency survey strategy designed to remove risk and deliver clarity.

Key elements included:

• Deployment of Vehicle Mounted GPR, enabling rapid data collection across the full survey extent with minimal operational footprint.
• Use of the Kontur Stepped Frequency Continuous Wave System, providing excellent penetration depth and resolution suitable for pavement analysis and complex buried features.
• Night-time operations, ensuring disruption to road users was kept to an absolute minimum while maintaining survey quality and safety.

The final deliverables equipped the client with all necessary intelligence for informed decision-making:

• A comprehensive plan of results
• Cross-sectional analysis of pavement construction and material thicknesses
• A detailed technical report outlining findings, risks.

Summary  

The Corstorphine Road project demonstrated the capabilities of Malcolm Hughes in delivering high accuracy, non-intrusive subsurface data for Highways clients managing significant operational risk. Through our specialist Vehicle Mounted GPR solution and deep expertise in Underground Utility Mapping, we successfully addressed the client’s core challenge: mitigating the danger posed by previously unknown buried obstructions. The final report revealed hundreds of previously undetected buried obstructions,  enabling the council to mitigate risk and prevent further damage to road-resurfacing machinery.

The strategic use of the Kontur Stepped Frequency Continuous Wave GPR System, combined with low-disruption night-time deployment, ensured that the client received precise, actionable data, eliminating uncertainty, supporting safer resurfacing operations, and reducing the likelihood of costly future damage.

This project reinforces Malcolm Hughes’ position as a trusted provider of high-accuracy, technology led utility and pavement mapping services across the UK’s Highways sector.

Find out how we can support your underground mapping project or survey requirements today by requesting a call back from one of the team.