Gardesana Tunnel Expansion Nears Completion After Landslide Repair

It is beginning to see the end of the tunnel that will connect Limone to Riva del Garda, which became essential after the last landslide on December 22nd that cut the Gardesana road in two at Rocchetta. Work is proceeding quickly, and yesterday a delegation of politicians and technicians from Brescia and Trento visited the construction site.

Participants and technical staff present on site

For Brescia, there were Mauro Parolini (provincial assessor for Public Works), Bruno Faustini (President of the Mountain Community Parco dell’Alto Garda), Battista Martinelli (mayor of Limone), and Pieremidio Baldassarri (assessor for Public Works in Limone and the Mountain Community). Explaining the situation were engineer Raffaele De Coll and project manager Enrico Zambotti, both from the Province of Trento.

Progress of work and technical methodologies

The mountain was drilled perpendicularly (157 meters of excavation) starting from the old state road and extending into the heart of the «Rocchetta», with the new tunnel intersecting approximately halfway along its path. This allowed four work sites to operate simultaneously: from the central point of the new tunnel working south and north.

At the same time, work from Limone and Riva proceed, heading towards the central point. On the site, work speeds are high, and very fragmented rock has been encountered, which, however, is not soaked with water; otherwise, says Raffaele De Coll, «it would have been a disaster».

Measures to accelerate and make the work safer include installing lighter arch frames (semi-circular metal arches), which set within 24 hours and are pre-reinforced with concrete. The result exceeds that of standard arch frames.

For fixing, 4-meter-long „nails“ are used. More time is saved with the highly specialized and complex cementing system, which delivers results in 15 minutes instead of 30. Technical choices had to consider that the tunnel will be temporarily open in July.

Perspectives and technical details

Temporary installations for lighting and ventilation will be set up. The resulting tunnel will have a radius of 5 meters, allowing the construction of a roadway with two lanes of 3.75 meters each. Additionally, two lateral sidewalks will be included.

To fracture the rock, explosive charges are used, each capable of removing about 3 meters of stone. The final blasts are scheduled between June 12 and 15, after which there will be a single borehole, and the distance between Riva and Limone will be shorter and certainly safer.

The excavation of the new tunnel results in approximately 130,000 cubic meters of material, most of which will end up in the lake just south of Riva, to extend the lakeside promenade towards Limone. About seventy workers alternate shifts for the construction of the new 987-meter tunnel.

Regarding the timeline for completing the work provisionally, allowing car and bus passage, the contract calls for completion by next July 27th. If the company exceeds this deadline, a penalty must be paid. However, if the work is finished early—highly likely—the company will receive an incentive bonus: around 40 million euros per day.

There was a growing belief that the work could be finished and open to traffic (excluding finishing touches) around July 15th. Yesterday, some whispered an even earlier date: July 8th.

Next steps and considerations

This may be related to the recent visit of Italian President Carlo Azeglio Ciampi. The first major milestone could occur tomorrow or Thursday, when the two tunnels, being excavated between the middle of the gallery and Limone, are joined.

Yesterday, only 50 meters remained before the last layer of rock fell away. Work will continue for a few more days between the central point of the gallery and Riva, where 200 meters are still needed to bring down the final diaphragm wall.

The finishing work on the new gallery remains to be completed, and these are not insignificant, especially considering their costs, which are significantly higher than those of excavation (45 billion euros versus 28 billion). It will be necessary to see if it is required to follow a European procurement process (which could take months) or if it is possible to proceed swiftly, as was done for this tunnel—substantially compressing the timeline.