Parapet integrity

Deterioration can occur inside the closed hollow sections and fastening bolts of bridge parapets, due to them often receiving little maintenance after installation. Visual inspection is insufficient to determine the integrity of these hidden features.

JF Strainstall offer a comprehensive service for condition investigation on bridge parapets and highway safety fences using several different services.

Though parapets are included in bridge inspections, the detection of their corrosion is incomplete by visual inspection alone. We recommend cursory checks using non-destructive tests at a sample of locations and periodic intervals. Where there are specific concerns of deterioration, more thorough investigation programmes might be appropriate. We can advise on the appropriate extents of testing suitable.

In some instances, vehicles have collided with parapets when attempting to access bridges with height or width restrictions. Undetected defects caused by these collisions lead to bridge parapets not meeting the intended rated resistance. Highways England provides advice on management of parapets, including risk ranking and prioritising upgrades. 

JF Strainstall can, using the breadth of our specialist teams, provide services including:

• Collating and review of record information
• Visual inspection
• Ultrasonic thickness measurements for posts and rails – for which we suggest B-scans to establish both minimum and average thickness
• Bolt scanning by phased array ultrasonic testing
• Weld inspection and testing
• Bolt load testing and certification
• Paint inspection and testing
• Inspection and measurements at zones of impact and use of ACFM technique for damage measurements
• Physical load testing of barrier system (static or dynamic)
• Monitoring for changes in condition or safety fence tension
• Since parapet resistance is reliant on the supporting structural plinth, we can extend investigations into the steel or concrete components around
• Risk rating and recommendations for management programme