Jacked underpasses

We have been equipped to install jacked underpasses since 1978. Over the years, albeit with additional implementation improvements and variations, we participated in part of the jacking work for the Rome Metro (having constructed most of the relevant structures themselves). An image illustrates work performed on 200 m of the B Line under the Tiburtina railways station in Rome. Other relevant projects include the bridge on the Lamasinata river in Modugno (province of Bari) with a crossing width of up to 70 m, all the underpasses of the doubling of the Pontremolese line and many others.

The system we adopt is characterised by a number of particular methods:

We do not envisage a sliding slab and concrete abutments (the sliding slab is replaced by a low thickness wooden caisson which accompanies the box culvert and the opposing wall is composed of a wooden and mostly steel plate capable of distributing the necessary thrust on the rear relief).
Advancement is subject to an altimetric adjustment system, with the front hull mounted on the slab with dedicated adjustable front plates
We provide steel advancement cutting shields welded to the front armature, these must be o be sunk into the ground during advancement to maintain the stability of the embankment
The system adopts jacks with a useful travel of 150 cm, with dedicated metal spacer shims inserted between the jack plates and the advancing box culvert

This system is unique in the market and its adoption avoids the need for temporary concrete artefacts (which would in part be abandoned in the ground and in part demolished at the end of jacking operations) and above allows for opposing elements to be fitted during the curing phase of the final castings (with appreciable savings in terms of safety overheads and lead times).

Several years of successful underpass projects: