Highways England’s pledge to review its bridge inspection regime in light of the recent Polcevera viaduct collapse has sparked fresh calls for more funding to be made available by central government.
Experts in contact with New Civil Engineer said the ‘unsexy’ nature of inspection meant the practise had been starved of cash in recent years, with politicians preferring to prioritise headline-grabbing building projects. In turn, inspection contract decisions are very often driven on price.
“The age-old problem is that maintenance isn’t a tangible thing, so the people with the money would much rather show off something like a new school instead. It has always been the way, but not having adequate cash puts pressure on the whole chain,” explained Waterman Group regional operations director Amrit Ghose.
Ghose, co-author of the Construction Industry Research and Information Association’s guidance on hidden bridge defects, insists the current testing approach generally works well, noting a gradual trend away from the established two-year and six-year cycle of general and principle inspection towards risk management.
“Inspections and testing are being targeted where they may have a greater effect. That means a thorough understanding of loading effects, deterioration and durability is required of the bridge inspector and bridge maintenance teams.
“If a bridge has critical elements or the cost of deterioration is high it makes sense to inspect more regularly. The skill engineers need to have now is being able to influence how budgets are spent,” added Ghose.
Bridge collapses in the UK are a thankfully rare occurance, suggesting the current system works well. The 2009 collapse of a railway bridge near Stewarton in Ayrshire, blamed on unidentified corrosion, is the only significant example of systemic failure in recent years.
And while many in the sector often turn to the expensive Hammersmith Flyover remedial work as an example of industry failure, the evidence suggests long-term and on-going management of its corrosion was ultimately an inspection success story.
Highways England has already begun insisting that inspectors undertaking work on its behalf have completed the Bridge Inspection Certification Scheme, something Ghose believes is more for show than necessity.
“The certification is fine in itself but for individuals completing it is expensive and onerous. There are many excellent inspectors who don’t have it and they take huge professional pride in their work – I’d rather see effort put into a system where those managing the infrastructure can afford to award inspection contracts on the basis of quality and completeness of the testing.”
How inspection contracts are written is another bone of contention. One engineer, who didn’t want to be identified, said some local authorities simply specified a ‘total number’ of inspections for their bridges over a set period, rather than insisting how many times each bridge needed inspection.
“I’ve heard of cases where a bridge will be inspected four times a year simply because it is close by and easy. The numbers are ticked off the contract and other bridges don’t get inspected at all,” they explained.
Peter Howe, principle engineer at WSP, said his past experience in the oil and gas industry highlighted some failings in land-based inspection.
“The offshore industry wants rigorous testing because structures can deteriorate quickly. When things do fail you can look back and examine the whole picture. Inspection for bridges on land are far more insular – it is very often difficult to look at a timeline and the root causes of what is going wrong. There is a real lack of investment in data management,” he said.
Howe is also an advocate for more risk-based assessment which he said makes it easier and quicker to implement special, more in-depth inspections should the need arise.
“You have to feel for those managing the infrastructure, such as local authorities. If engineers are coming to them saying special inspections are needed on a number of structures, there often isn’t the money to do them all.”