Italian contractors, it would seem, are currently enjoying la dolce vita. Tunnel construction is as much a part of Italian life as Berlusconi’s love affairs.

There are four major projects currently under construction that include significant tunnelling contracts, plus another eight that are at the tender, design or financing stage.

That there are so many schemes involving tunnelling work is of little surprise to Ashurst partner Carloandrea Meacci. The firm’s Energy, Transport and Infrastructure department in Milan has been engaged as a legal adviser on several recent project financings for schemes where tunnelling is a key part of the construction package.

Variante de Valico
Themost significant project being built is the EUR 3.2bn (USD 4.3bn) widening of a 62.5km section of Italy’s A1 between Bologna and Florence and construction of a 37kmbypass, known as Variante di Valico (variation of crossing) through the Apennine mountains.

Stretching from La Quercia in the north to Barberino in the south, the Variante di Valico project includes 18 tunnels with a total combined distance of 17.9km.

Tunnelling work on the scheme has been split into six packages. The project’s latest milestone came on the base tunnel package, which holed through in December 2010. Part of Section Badia Nuova-Aglio (11.2km) of the Variante di Valico, the base tunnel is the largest highway tunnel in Italy with 8.6km length and 180 sq m section for each carriageway. The project is being carried out by Todini Costruzioni Generali (Salini Group) and will complete in 2012.

The tunnel route crosses a rock mass that belongs to the Tuscan formation (Monte Cervarola) and the Ligurian formation (scaly clays). To tackle the geology, drilling and blasting was used for half of the drive and mechanical means for the other half. In Monte Cervarola sandstone, systematic drilling and blasting was used. In the scaly clay, the tunnel face was pre-reinforced with fibreglass pipes injected with grout prior to excavation with a hydraulic breaker.

Tunnelling in the Monte Cervarola rock mass was executed with two Tamrock Axera T12 Data jumbos. Shotcrete was sprayed with CIFA CSS PAS 307 pumps. In the scaly clays, excavators CAT 345 BII and Hitachi ZAXS 350 equipped with breakers Rammer G 100 and G 88 were used. For tunnel support, bolts, twin IPN 180-220 steel ribs and fibre-reinforced shotcrete were installed. Other means used were Dieci Pegasus platforms, Atlas Copco compressors, CTM generators, Flakt Woods ventilators and CIFA formwork.

The other package on the project to hit the headlines recently was the Sparvo project, on which the world’s largest TBM, a 15.62m diameter Herrenknecht Earth Pressure Balance Shield, was accepted by the JV contractor Vianini Lavori /Toto Costruzioni Generali/Profacta in December.

The giant TBM is currently in the process of being dismantled and shipped from Herrenknecht’s Schwanau factory to Italy, enabling final assembly to commence on site in February. It will start excavation of the first tube near Florence in a northerly direction in May 2011 with plans for the new route to open by the end of 2013.

The twin tube Sparvo tunnel will set new record in mechanised tunnelling. At 2.5km long, each tube includes a two-lane road and a third emergency lane.

Loose soil containing explosive firedamp is anticipated along the 5km stretch. In order to achieve a high degree of safety and swift tunnelling performance, the building contractor opted for an EPBM.

The 4,300t machine with its 12,000kW cutterhead power will set a new record in mechanised tunnelling as far as the drilling diameter is concerned.

Lombardy Tunnels PPP
The other main road tunnel project taking place is not so much a single scheme, and doesn’t involve any new construction – it is a EUR 150M (USD 205M) programme of restoration to 96 tunnels in the Lombardy. Run as a public private partnership by Italy’s national highway authority ANAS, the scheme is continually letting out small packages of work – the most recent being on the refurbishment of the SS237 between Tormini and Barghe.

Milan Metro Line 5
On the rail side of things there are two key metro schemes currently under construction, one in Italy’s capital and one in its financial centre.

Milan’s M5 line will run north for 5.6km from Garibaldi main rail station to Bignami with intermediate stations at Isola, Zara, Marche, Istria, Ca’Granda, Bicocca and Ponale – from where the shield has already been relaunched on its southbound run after the first intermediate breakthrough.

At Garibaldi and Zara the M5 line will interchange with the metro lines M2 and M3. The line is to come into operation in two stages: the Zara-Bignami section by March 2011; and, the final, 1.25km long Garibaldi-Zara section by May 2012.

The Design, Build, Finance Operate concession for the project was awarded to a consortium of Astaldi, Ansaldo, Torno, Alstom and ATM for 32 years, including a five year construction phase. Design and construction of the line will cost some USD 740M and it is Italy’s first major urban transport project to use project finance.

The financing, signed in December 2007, totalled USD 817.35M. Debt and equity contributions broadly split 50:50 – total equity is USD 412M, while total debt is USD 405.35M. The debt package breaks down in to a 23-year term loan of USD 269.16M, a construction “bridge” loan of USD 58.83 million to support spending during the construction period, a USD 29.42M standby facility and a USD 14.71M working capital facility – both with tenors of 23 years to support cost overruns at any time during the concession – and a VAT facility of USD 33.24M.

The debt was provided by: Societe Generale, Dexia, WestLB and Mediobanca.

The new line with automatic, driverless trains is eventually to be extended to Monza, it is proposed, with four intermediate stations. There is also a proposal on the cards for a westward extension from Garibaldi to San Siro with nine intermediate stations.

Lovat’s EPB shield TBM, despatched to tunnelling subcontractor Ghella, is advancing well in its drive on the scheme. The 9.4m diameter mixed face shield is driving more than 3.5km through gravel, sands and some weak silts with cover of 8- 12m. The drive, in the north of the city, is mostly above the water table.

Fitted with ripper teeth and scrapers, the cutterhead has power and maximum torque of 2,700kW and 24,940kN at 1rpm, respectively. Tunnel lining is 8.15m i.d., 350mm thick with rings 1.5m long.

Rome Metro Line C
Rome’s Metro Line C is among the most significant and challenging infrastructure projects underway in the world today.

Comprising twin 17.6km tunnels beneath the ancient city, construction of the project is being carried out under a turnkey contract by the joint venture Metro C (formed of Astaldi, Vianini Lavori, Ansaldo Trasporti-Sistemi Ferroviari, Cooperativa Muratori e Braccianti di Carpi, Consorzio Cooperative Costruzioni).

The JV is using four identical Herrenknecht EPB-TBMs, with cutter head diameters of 6.71m and a 10.7m shield length. The four TBMs have all completed their main drives, the most recent being the fourth TBM S-479’s completion of the 2.8km Malatesta-Pozzo drive in July 2010.

The two machines S-409 and S-410 successfully reached the first milestone as October 2009, have been dismantled and were launched for their second drives late last year. On these drives the TBMs will tunnel the routes T3 and T4 from Malatesta to close to Venezia station.

On this stretch the machines will cross beneath the famous Colosseum building with an overburden of 30m.

The design of the four identical Earth Pressure Balance Shields (6,690mm diameter) for Line C is specifically adapted to the geological conditions of the route. An opening ratio in the cutting wheel of some 40 per cent allows a better flow of material into the excavation chamber, thus reducing clogging in the openings.

The high opening ratio also increases the contact pressure of the tools which provides for a better penetration. The cutting wheel, which is rotatable in both directions, is equipped with a total of 100 scraper tools, 16 buckets and an overcutter for soft ground. The discs can be accommodated in 13 casings and can be exchanged for rippers to suit the geology.

Two rotors at the cutting wheel and four stators at the pressure wall provide for a good mixing of the excavated material in the excavation chamber together with the cutting wheel arms, and a good consistency of the material is obtained by injecting foam.

With the help of conditioning, the torque required and wear-and-tear can be reduced to a minimum. The drive’s torque of 7,027kNm with 1.46 rpm is generated by nine hydraulic motors. The four axial piston pumps for the hydraulic motors are driven by four 400kW electric motors.

The shields are designed for a maximum pressure of 5 bar and are equipped with 19 double cylinders which generate a thrust force of 50,558kN. The shields are additionally equipped with two joints. One joint is an active control joint between front shield and centre shield, and the other is a passive joint between centre shield and tailskin. The two joints allow a narrow horizontal radius of a little as 150m.

The machines are also equipped with a bentonite control system to secure a constant pressure in the excavation chamber even outside working hours. If the predefined pressure in the excavation chamber falls, a pressure regulator automatically feeds bentonite from pressure tanks into the excavation chamber.

For the filling of the annular gap between soil and ring segment the so-called bicomponent system is being applied instead of filling the gap with conventional mortar and thick-matter-pumps. The bicomponent system involves pressing into the annular gap a special mortar mixture (component A), and the accelerator (component B) through six openings at the tailskin end with the help of six eccentric screw pumps. After mortar and accelerator have mingled, the mixture becomes solid within a few seconds. This avoids subsidence which can occur, for example, if the mortar hardens too slowly.

The tunnel lining is consists of 300mm thick precast reinforced concrete segments with an internal diameter of 5.8m. Each prefabricated ring is 1.4m long and has six main segments and a key. The rings are of universal double tapered type and fit 19 possible different positions depending on the radius of curvature to be obtained. Segments are cast in a prefabrication plant by using a fixed formwork installation for concrete steam curing.

In total, Line C will be 25.5km long including 17.6km underground and with a total of 30 stations.

Coming up
Rome is also planning an extension of its Metro Line B, and a new metro Line D. However, both are being financed as PPPs and are stuck in the financing stage due to cost concerns and land acquisition issues.

Meanwhile in Milan bidding in December closed on the USD 2.2 billion Milan Metro Line 4 PPP, which will be a 14.7kmtrack from the western suburb of Lorenteggio to Milan’s city-based airport, Linate in the east. There are two bidders for the scheme – Impregilom and a JV of Condotte, Pizzarotti and RATP.

Also in Milan, financing is in progress for the USD 280M extension of Line 5 by 5.6km from Garibaldi station located in the centre of the city to the northwest suburbs, with ten banks agreeing to lend to the scheme in December 2010.

On the railways, tunnelling work on both the Catania railway extension and the dualling of Genoa-Ventimiglia line have both been recently tendered.

And on the roads, Impreilio has won contracts for two major schemes.

The Milan Outer East Orbital is a EUR 1.5bn (USD 2bn) project that is being privately financed under a 50 year concession. It is a 33km new toll road linking the Milan-Venice A4 motorway and the Milan-Bologna A1 motorway between Agrate Brianza and Melegnano respectively. The project will comprise some 23.6km of embankments, 5.5km of cuttings, 1.8km of viaducts and some 2.1km of tunnels.

The Lombardy ‘Pedemontana’ motorway meanwhile includes 13km of tunnels. The project comprises construction of the first section of the Como and Varese orbital roads and of the link between the A8 and A9 motorways (from Cassano Magnago to Lomazzo). Construction work includes approximately 47km of motorway and secondary roads. Impregilio’s work is the first contract awarded on what is a EUR 4bn (USD 5.5bn) privately financed PPP scheme.


Rome Line C site by Monumento Nazionale a Vittorio Emanuele II