This month contractors’ men at the southern portal will be eating their hefty and delicious Italian site lunches in the brand-new canteen buildings just erected in the long, narrow work-site south of Bodio. Offices for engineers and workers from half a dozen contractors’ firms are being finished alongside.

A variety of contracts are under way here, including two driven rock tunnels, a difficult loose ground section and one cut-and-cover section, visible by the bizarre site of the tunnel portal standing as newly-erected formwork in open ground. As the tunnel takes shape it will be covered by a new embankment which will carry a re-routed local highway.

The first of the tunnels, already about 200m in at the end of August, is a 3.2km-long, 5m diameter drive eastwards at right angles to the main route. This will cut through the tip of the mountains to a valley where spoil processing and washing is to take place. "A long conveyor will carry the stone, and there will be room for a service truck to run alongside," explains Mario Orsenigo, AlpTransit engineer.

Local contractor LGV Impresa Costruzioni of Bellinzona is working with France’s Spie Batignolles, known as Infra 2000 in Switzerland, on the SFr23M tunnel using a second-hand Robbins TBM brought in from the Lesotho Highland water project in Africa. It has rock support drills mounted just behind the head. Some crown support is needed in the otherwise good-quality rock because of horizontal bedding.

The second tunnel is aimed at speeding up the main drive. The twin Gotthard bores will curve off gently from the Gotthard main line which runs up the valley alongside the motorway and the Ticino river. But just where it enters the mountains is a huge fan of accumulated rock debris, some 800m of loose boulders – "up to the size of a house", as Mr Orsenigo describes it.

To get through this will require delicate work using a grouted umbrella system of support, he says, and it will take time – far too much time for the Gotthard schedule.

To let the main drive proceed, therefore, the second bypass tunnel will go around the back of the slide, creating two sections of the main tunnel at the end in which the TBMs can be assembled. These can drive north while the difficult slide work continues.

The SFr45M bypass is being driven by drill and blast by a joint venture of Batrigroup, Frutiger from Thun and German firm Bilfinger & Berger. An Atlas Copco jumbo works the gneiss face and, once blown, a German Schaeff shovel and conveyor loader charges Volvo dumptrucks. Work was some 100m in August on the 7.8m-high tunnel.

The first 400m of the fan will meanwhile be tackled by the cut and cover work forming a concrete vault and backfilling; local firm Mancini & Marti from Bellinzona is doing this SFr13M job; the second, more difficult, section is a SFr53M contract with two Italian firm Fondazioni Specialisti, and Pizzarotti along with local firm Muttoni and E Ferrari.

Other work will include forming a canal and reservoir system to hold the water from the main drives, both during drives and when it is in permanent use. Water has to be cleaned and also cooled before discharge into the river because it will emerge from the deep tunnel at up to 45°C.

The main drive has yet to be awarded.
The fan of debris just after the portal area. The fan of debris just after the portal area. The fan of debris just after the portal area. Concreting the first portal section for the cut-and-cover work Concreting the first portal section for the cut-and-cover work Location of the Bodio work-site complex Location of the Bodio work-site complex with spoil disposal, water treatment and TBM assembly arrangements
The spoil-disposal tunnel is well underway. The spoil-disposal tunnel is well underway. Site preparation at Gotthard involves several major tunnels. Here the by-pass tunnel at Bodio is mucked out. Site preparation at Gotthard involves several major tunnels. Here …
Related Files
Location of the Bodio work-site complex