Aperio - Geophysical and Non-Destructive Surveys

Aperio are international specialists in non-destructive investigation and geophysical surveys. The company has unrivalled experience in railway applications including:

• Trackbed condition and thickness surveys
• Investigation of cavities and structures below the railway
• Tunnel surveys
• Non destructive investigation of railway structures and buildings

Aperio are registered under the Achilles Link-up scheme as approved suppliers of geophysical surveys to the UK rail industry. The company has a proud record of innovation as recognised by the 2003 SMART award for development of systems for high-speed trackbed surveys.

WHY NON DESTRUCTIVE INVESTIGATION?

Non Destructive Investigation (NDI) provides condition and construction information quickly and with minimal damage to the assets under investigation. Surveys are quick and use highly portable equipment, making for safer work practices than 'traditional' methods such as coring, boring and digging. The results can provide a representative picture based on continuous rather than point measurements to enable more cost effective decision-making and better management of railway assets.

GROUND AND STRUCTURAL INVESTIGATION METHODS

Aperio offer a complete range of techniques and expertise to provide construction and condition information to help engineering clients make better decisions. Geophysical methods for ground investigation include:

• Ground penetrating radar (GPR)
• Ground resistivity
• Ground conductivity
• Microgravity
• Magnetic methods.

Non destructive methods for structural investigation include:

• Ground penetrating radar (GPR)
• Ultrasonics
• Metal detection instruments
• Moisture meters
• Infrared thermography
• Remote visual inspection methods.

TRACKBED CONDITION AND THICKNESS SURVEYS

Applications of geophysics include determining depth of ballast, mapping ballast/formation intermixing and contamination, detecting shallow services and structures obstructing track renewal operations, and testing sleeper condition.

GPR surveys have been adopted as a best practice element for all Network Rail track renewal projects in the UK, and provide a continuous view of the ballast thickness and condition. GPR is a powerful tool in preventing 'wet beds' and hard spots, which have an adverse affect on ride quality and lead to rapid deterioration of the track.

Aperio provide high-resolution data by using the fastest radar systems available and some innovative software tools. This technology enables the progression from walking surveys to high-speed surveys with instruments operated from survey trains.

INVESTIGATION OF SUBSURFACE CAVITIES AND STRUCTURES

Applications of geophysics include investigation of 'lost' structures such as unrecorded culverts, drains, infilled bridges etc., mineworkings and blind access shafts, voids from burrowing animals and solution features: swallow holes, caves etc.

Surveys can define the location, shape and depth of unrecorded buried structures including culverts, bridges and disused arches and can map any disturbance of the trackbed above.

TUNNEL SURVEYS

Applications of geophysics include determining lining and invert thickness, lining condition (delamination and voiding), location of blind access shaft, and moisture variations.

Section 7.5 of the Network Rail Code of Practice recommends the use of non-destructive techniques including GPR, thermography and other geophysical methods as part of tunnel examinations. Tunnel surveys often use GPR and ground conductivity to provide a more comprehensive condition assessment than visual or hammer tapping surveys.

NON DESTRUCTIVE INVESTIGATION OF RAILWAY STRUCTURES, PLATFORMS AND BUILDINGS

Applications of non destructive and geophysical methods include:

• Brick arch thickness
• Profile of backing/haunching layers above masonry arches
• Delamination and voids at any depth within brick linings
• Reinforcement detail in concrete
• Structural arrangement of buildings, platforms and structures
• Condition of buildings, structures and platforms - voids, corrosion, moisture etc.

Non destructive methods have been widely used to investigate the construction arrangement and condition of structures such as bridges, station platforms and railway buildings.