Heritage railway bridge renovation works – steelwork and brickwork repairs, bird mesh and fencing.
Bridge 8 had restricted traffic loads imposed after inspections highlighted corrosion had weakened some steel beams and connecting components. Unfortunately, COVID-19 lockdowns meant the income from running the steam railway dried up and the traffic management had to stay in place until funds and timeframes became available. During an eight-week window of opportunity between December’s Santa Specials and the scheduled spring re-opening of the railway for 2022 business, repairs were commissioned – having been tendered in 2021.
The scheme called for 2 main beam strengthening plates to be replaced with new steel plates approx 7.5m long each and weighing approx 800kg, with the removal of over 300 rivets designed to keep the plates well and truly bonded together!
Montel were able to use in-house skills to place a protective stone mat over the track and trackside to mitigate having to remove the track itself. The same team renewed fencing to the wing walls, carried out brickwork repairs, re-installed modern bird mesh protection and then cleared all of the stone upon completion.
Our specialist partners were called upon to design and install a propping scheme to take the weight of the bridge and it’s traffic whilst components were removed, replaced or repaired.
Our scaffold partner erected and later cleared a bird cage scaffolding around the 56 No props that gave access to the underside of the bridge. It was also designed to withstand the loadings imposed by the teams, their equipment and the metal repair plates themselves. The scaffold was extended to enable the removal of the old plates as well as the loading, positioning and fitting of the new plates.
Our specialist heritage structural metalwork partner carried out the main repairs and when additional repairs were highlighted as critical, we were able to call on a second highly skilled contact to assist with additional repairs.
A fully mobile shot blasting partner was able to clean more metalwork, at very short notice, after the Client’s engineers highlighted issues not previously noted – and wanted to investigate further.
The combined efforts of the teams made it possible to not only complete the contract repairs but also complete additional repairs to bridge 8 before moving to bridge 10 to complete unscheduled repairs not tendered previously.
The whole scheme came with risks and a large number of unknown conditions prior to starting. These conditions and unknowns would only be confirmed after the scaffold was installed and the engineers could get up close and personal to rigorously inspect the steel components. When Montel were awarded the contract, we called a collaboration meeting with the client and heritage specialist. Risks, provisional items, time constraints and program were discussed at length and a strategy agreed in advance of starting on site.
The inspections found that some elements were in better condition than expected and others were in need of more attention than expected. It called for immediate action and we were able to introduce a skilled mobile fabricator to our heritage specialist. Together with the engineers we could then plan to carry out necessary steelwork repairs. Our in-house team were able to remove brickwork from the jack arches to allow inspections and repairs, before making good and installing the bird mesh.
The speed and success of the team working collaboratively on Bridge 8 presented the chance to carry out repairs to bridge 10 within the eight-week track possession window.
Through specialist partners, we were able to offer a lightweight propping scheme that could be installed and removed in half the time – providing valuable extra time to complete as many repairs as possible within the limited track closure. What we learnt was that scaffold floor area was reduced as a consequence – there’s a trade off between speed and available space that needs consideration when assessing the level of repairs.
We also introduced a skilled mobile fabricator to the team who was able to prove his MIG skills and standard of workmanship were more than a match for the specification, when stick welding was previously the preferred option.
Investing in a set of rechargeable site flood lights allowed directional lighting wherever and whenever needed in the darkened conditions under the bridge deck. This reduced the need for additional generators, tripod lights and trailing leads on the scaffolding – allowing trades to focus on their immediate work in a reduced risk area.
Our heritage steel repair specialist had proven experience with the difficulties associated with removing rivets from historic bridges and after early engagement and talks about the risks, with limited head height for conventional jacks, they designed and fabricated a prototype clamp to incorporate a bottle jack to push the rivets out from underneath. What we learnt was even 30t of pressure wasn’t enough to push a 1903 rivet out of its position where 3 or more plates had been joined together!