Working in October 2023 the Rail Systems Alliance Scotland (RSAS) team battled through the weather and Storm Babet to successfully install new longitudinal timbers at Shore Street Inverness over a 54 hr 'no trains' engineering access window.

The existing walkways over the bridge were over 60 years old and at the end of their lifecycle, with signs that the weather was now gaining access and rotting the timber. There had been various visits in the preceding weeks to plan the works and how the full renewal of the timbers would be carried out.

The process of the actual removal of the existing timber bearings was challenging because they were fixed in position by bitumen poured in when boiling hot all those years ago, which still held the old timber in its mighty grip.

The new timbers are made from FFU synthetic wood (fibre-reinforced foamed urethane). Compared to conventional timbers they have a far greater lifespan meaning that future renewals won't be required for potentially decades to come. Since introduction in Japan in 1980, they haven't required any remedial works and have a predicted life expectancy of 50 years before renewal is considered.

At the end of their lifespan they can also be recycled into other products instead of scrapped, bolstering their green credentials. Due to their synthetic structure, they do not absorb water, oil, lubricants, etc. thus are not only greener but offer a safer alternative to traditional timber.

Drilling into the composite timbers provided a challenge versus traditional methods. In one of our first installs of this type we found our normal tools were stressed to produce the results needed.

With anything new, there is always a learning curve, and any difficulties were quickly overcome.

Network Rail also provided us with a sequence of photos showing the process of lifting the rails, removing the old longitudinal timbers and replacing them with the FFU beams on the bridge over the River Taodail near Strathcarron on the Kyle Line. This project was completed in the week before the Shore Street works. The job was finished in 29 hrs, and the track was handed back 6 hrs ahead of schedule.

The rails were lifted from the bearing timbers and laid temporarily on the central yellow GRP walkway while the old timbers were lifted out and the new FFU bearings lowered into position.

[Left] The rails have been moved to the centre to expose the old timbers, and the replacement FFU components have been laid out ready for installation.

[Right] One of the old bearings has been attached to the crane, ready for removal.

[Left] One of the new bearings being carefully lowered into position.

[Right] Perfect fit. The first beam ready to be bolted onto the bridge by securing bolts and steel lugs.