Once a quarter, the Rochester Bridge Trust carries out overnight maintenance of its bridges. The purpose of this is to safely complete activities that require single lane closures, at a time when they cause the least disruption to the travelling public.
During the first week of December, single lane closures were alternately carried out on both bridges for five nights. This enabled a range of activities to be carried out, including: cleaning the bowstring-shaped trusses of the Old Bridge; cleaning the roof of the Service Bridge; cleaning the expansion joints on the Old and New Bridges; cleaning the granite; and the trial installation of bird mesh to reduce the build-up of highly corrosive guano.
During this time, Term Maintenance Contractor FM Conway also trialled the use of more environmentally-friendly equipment. On this occasion they brought in an electric MEWP, or mobile elevating work platform (a scissor lift in everyday language). This particular item of equipment was not a success because it did not have jacks – self-levelling legs – which meant it required a lot of additional, time-consuming, manoeuvring for safe use on the road camber.
Bridge Manager James Booth said: “The MEWP is needed to safely, quickly and easily raise an operative closer to hard-to-reach areas, so it must have good manoeuvrability and a stable base. It’s a shame this particular item couldn’t meet our full requirements, but part of an engineer’s job is to test things, review their success and see how improvements can be made. We will now look at what other types of electric MEWP are available to help us meet our carbon reduction target.”
Another aspect of the overnight works was replacement of a set of faulty light fittings on the New Bridge. This included one lantern that had developed a hardware fault soon after installation. The fitting was left in place while a new lantern was ordered from the original supplier, it was then stored until it could be replaced at a time that caused minimal disruption – alongside other works.
In the meantime a few other light failures also occurred on the New Bridge. It was not immediately apparent why this had happened and so electrical investigations had to be carried out. These eventually revealed a neutral fault inside one of the termination boxes – something that could be easily rectified during the overnight lane closures – as well as some lights that had not been switching off, these have now been reset.
James added: “Work on a bridge is never done because it is in constant use and impacted by the environment, however carrying out these regular maintenance works means we are able to monitor the whole structure and minimise the chances of larger, more disruptive interventions being required.”