Milestone

Webuild completes Serra Lunga tunnel on Salerno high-speed line

By Staff Writer  |  15 August 2026

A consortium led by Webuild has completed excavation of the 800 metre Serra Lunga tunnel on the Salerno to Reggio Calabria high-speed and high-capacity railway, and has begun excavation of the Sicignano tunnel.

The company reported the progress on 10 August 2026. Both tunnels sit on Lot 1A, Battipaglia to Romagnano, part of the construction of 35 kilometres of railway in the Province of Salerno. The works are being carried out on behalf of Rete Ferroviaria Italiana.

Serra Lunga was excavated by the tunnel boring machine Leucosia, which has a cutterhead of more than 13 metres in diameter and is among the largest mechanical excavators the company operates in Europe. Working in ground described as highly variable, the machine reached peak excavation rates of around 15 metres a day, and installed more than 2,900 precast segments to complete the tunnel's final lining. More than 100 specialist technicians worked on the machine.

Serra Lunga is the second tunnel completed on Lot 1A. The first, Caterina, was excavated by the tunnel boring machine Mireille, which had previously worked on Line 16 of the Grand Paris Express in France and was subsequently refurbished at the company's facility at Terni. After being relocated by approximately 400 metres, Mireille has started a drive of more than 2.5 kilometres towards the future Sicignano tunnel, through the hills of the Sele Valley between the municipalities of Buccino and Sicignano degli Alburni.

Elsewhere on Lot 1A, excavation has started on two cut and cover tunnels and on the Cerreta natural tunnel, and work continues on viaducts. Eight natural tunnels are to be excavated on the lot using four tunnel boring machines. More than 2,000 people are at work on the projects, supported by a supply chain of over 1,300 companies.

What the practitioner should take from this

Tunnelling by machine concentrates risk in two places: the ground and the machine. Both are worth examining whenever a drive is reported as complete.

Ground first. Where conditions are described as highly variable, the contractual question is whether the encountered ground falls inside or outside the baseline the parties agreed. A geotechnical baseline report converts an argument about geology into an argument about a document, which is a far shorter argument. Where no baseline exists, the parties fall back on whether the conditions could reasonably have been foreseen by an experienced contractor, which is a question of fact decided long after the event.

The machine second. A refurbished tunnel boring machine redeployed from another project raises questions of ownership, residual life and responsibility for breakdown. Where the machine is the contractor's own, the risk of an extended stoppage usually stays with the contractor. Where it is supplied by the employer or by a third party, the allocation must be express, because a stopped drive stops everything behind it.

Relocation between drives is the third point. The 400 metre move recorded here is a programme activity in its own right, with its own access requirements and its own weather and lifting risk. On a programme with four machines and eight tunnels, the moves between drives frequently determine the critical path more than the drives themselves.