Cable-stayed rail bridge reaches its final span

The final deck segment of a new cable-stayed rail bridge was lifted into place this week, joining the two halves of the crossing over the river and completing a structure that has taken three years to build.

A careful lift

The 320-tonne segment was floated in on a barge and raised by strand jacks over a single tide window, timed so that the barge sat at the right height relative to the deck without any last-minute adjustment. Surveyors had less than 15 millimetres of tolerance to work with, checked continuously through the lift with total stations mounted on both approach spans. A gap that size closes fast once wind, temperature and the weight of the segment itself are all working against the crew, which is why the lift plan built in stop points at every stage where the numbers could be rechecked before committing further.

Why cable-stayed, and why this method

The design uses two pylons and a fan of stay cables rather than a single main span, which let the team build the deck outward from each pylon in balanced segments without needing temporary supports in the river below. That balanced cantilever method is what made the final segment the hardest part of the job: every previous segment was held in place by the cables already tensioned on either side, but the last piece had to be lowered into a gap between two structures that were each still finding their own equilibrium.

The people behind the lift

A marine crew handled the barge and tide timing, a specialist heavy-lift contractor operated the strand jacks, and a permanent team of surveyors and engineers monitored deflection and cable tension throughout. Weather windows were booked weeks in advance and held in reserve, since a lift of this scale cannot simply be rescheduled at short notice once a barge and crew are committed.

Next steps

Crews will now tension the remaining stay cables to their final design loads, working outward from the pylons in a sequence calculated to avoid overloading any single cable as the deck settles. Track slab installation follows once the deck geometry is confirmed stable, and commissioning tests, including load trials with weighted wagons, come after that. The line is expected to open to traffic in about a year, with the intervening months given over to systems installation, signalling and the extended testing a rail crossing of this scale requires before the first passenger service runs.