The Forth Rail Bridge is located nine miles to the west of Edinburgh. It is regarded as a crowning achievement of Victorian steel bridge building and its robust cantilever structure was designed to combat the high winds that had caused the failure of the Tay Bridge with significant loss of life eleven years earlier in 1879.
The bridge is composed of 54,000 tonnes of open-hearth steel. The world’s first-ever steel bridge, it was opened in 1890 when the future King Edward VII travelled to Edinburgh to hammer in the last of 6.5 million rivets. It has a surface area of 45 acres, and this led to one of the most persistent British urban myths; the legend that the moment workmen finish painting the Forth Rail Bridge they cross back over the estuary to begin painting the other end anew. This is one fable that can finally be debunked in 2012 after a £130 million, ten year project which fully refurbished the structure. After shot-blasting away 40 previous paint layers across the 2,500-metre cantilever structure, a 400-strong team applied 240,000 litres of durable epoxy paint to the bridge, which will now not need another coat for 20 years.
Health and safety considerations, as well as the need to avoid disruption to Train Operating Companies (TOCs) by minimising downtime on train movements have been the principal concerns of Balfour Beatty Regional Civil Engineering, who were the main contractor to Network Rail on the project. On average, there are between 180 and 200 train movements daily as the bridge is the principal artery between Edinburgh and Fife – and it had to be kept open at all times.
Automated warnings
Balfour Beatty entrusted track warning systems, safety procedures and safety maintenance to Vital Rail who provided a Safety Critical Management Team and associated support. Up until the completion of the painting and refurbishment, Vital supplied, maintained and operated an Automated Track Warning System (ATWS) across the length of the bridge. Indeed, the ATWS became an integral part of the bridge’s maintenance system during the works.
Vital’s activity on the project was co-ordinated from the company’s office in Bellshill, near Glasgow. The Vital Rail site supervisor for the project was Alan Richardson, who said: “The culture on the bridge is that your colleague will do anything for you. Previously, operatives had acted as lookouts for each other, so putting absolute trust in the Automated Track Warning System was a new way of thinking. The crew realised that, however much their opposite number wanted to support them, he could be fallible. The ATWS technology does not tire or have a ‘bad day’. When the men realised this, the equipment actually began to contribute to their peace of mind.”
The ATWS sirens which warned of an approaching train had to compete with wind, riveting and shotblasting. It was therefore a crucial feature of the Autoprowa™ automatic proportional warning system from ZÖLLNER Signal Systems Technologies that the microphones had the “intelligence” to evaluate ambient noise levels, and adjust the volume of warning signals accordingly. The ZÖLLNER system used on the bridge has been approved in Europe by a respected panel of independent safety assessors, Technischer Überwachungs-Verein (TÜV), and is fully accepted by Network Rail.
Automatic activation
Graham Gillan, Vital Rail’s ATWS manager, said: “Vital used a hard-wired fully automatic ATWS solution on this occasion. As a train neared the work site, the detector placed on the track would be activated when the train wheels ran over the treadle and audible warnings would combine with flashing beacons. This approach factored out human error. Dual redundancy was crucial so twin devices were installed at the ‘sighting distance’ based on speed and time in order to give the workforce – particularly scaffolders – adequate warning to secure their equipment. At the approach of a train, Balfour Beatty staff and their subcontractors working on the track, deck level and right up to the top gantries, would cease all activity.”
Graham continued: “At the end of the work site there was a strikeout treadle which cancelled the warning that had been generated. This approach proved crucial in an environment characterised by constant fog and sea fret. Not being reliant on visibility reduced downtime dramatically. Vital Rail also supplied safety critical personnel and track labour to contractors who needed to move materials around the bridge. All our staff have their PTS (Personal Track Safety) certification and where appropriate they also had Control of Site Safety (COSS) qualifications. Senior management from Vital formulated safe system of work plans and, in addition to Balfour Beatty, we briefed the various disciplines such as Pyeroy (painting)( and ThyssenKrupp Palmer (scaffolding).”
Useful RRVs
A significant aspect of Vital Rail’s work during the bridge refurbishment involved the introduction of road-rail vehicles (RRVs) for moving materials, leading to a reduction in the health and safety risks associated with manual handling. This approach is also being introduced by Network Rail through its own RRV Safety Improvement Programme, notably during a recent RRV exclusion zone workshop at the Westwood training centre near Coventry.
The main benefit of use of the RRVs, which are manufactured by Liebherr and Colmar, has been the reduction in manual handling and the associated risk of injury, which cannot be factored out however rigorous the safety protocols. Moving 15 tons of equipment on a single vehicle up to 320 yards at a time across a cantilever to the main works allowed Balfour Beatty to meet both safety and commercial objectives simultaneously.
Colin Hardie is a Construction Manager at Balfour Beatty Civil Engineering who has worked on the bridge for a decade. He said: “The breadth of offering from Vital Rail became apparent as they helped us implement a site-specific safety regime and put all staff through rigorous, tailored induction courses. This is a unique environment that is unlike any bridge, trackside or depot work our staff have encountered. Vital supervisors have helped us with the very occasional man-management issue but what has been really impressive is the rapport they have shown with all the contractors and trades here.”
Alan Richardson said: “The North Queensferry side of the bridge is particularly prone to fog and all parties agreed that the ATWS introduced by Vital Rail produced substantial savings across the board. Working conditions here are as tough as a any painter or scaffolder is likely to encounter anywhere in the world. The track is 45 metres above the firth, and while an operative will be aware that he is near water, he may not be able to see it which can be disorientating. Before any painting could be done, a crew had to be screened off from the environment in encapsulated areas supported by several tons of complex access scaffolding. The logistical and safety implications were complex. The days of there being a permanent railway ‘colony’ of fifty families in cottages at the east end of South Queensferry are gone, but even with the refurbishment project finished, Vital Rail will continue to have a responsibility for safety here as we have had since 2004.”
