INTRO: Formal authority has been granted for construction to start next year on the Milano - Bologna high speed line. This will form the last section of a high speed route which will transform rail travel in Italy’s primary north-south corridor

BYLINE: Roberto Renon

Managing Director


CONSTRUCTION work is due to start in the second half of next year on the long-planned Milano - Bologna high speed line. This follows the government’s formal approval of the project on July 23 1997, and means that Italy will have three high speed lines under construction at the same time. Work is already well under way on the Roma - Napoli and Bologna - Firenze sections (Table I).

Known from its shape as ’the Grand T’, the Italian TAV (Treno Alta Velocità) network will eventually extend over 1300 km. It will effectively duplicate the country’s three busiest rail corridors: the Po valley route from Torino and Milano to Venezia, the north-south dorsal from Milano to Roma and Napoli, and the link from Milano to Genova.

Since the project was launched, the technical specifications have been updated to allow for full integration with the embryonic European high speed network, meeting the characteristics defined by the Master Plan of the European Transport Commission in conjunction with the International Union of Railways. These include speeds in the 250 to 300 km/h range, axleloads up to 17 tonnes, and larger loading gauge clearances. Rail section, gauge, power supply and signalling will all be designed to provide interoperability with the high speed networks in other European countries.

Unlike the new lines in France and Spain, those in Italy have been designed for both passenger and freight trains. This requires a high degree of interconnection with existing routes, imposing specific design and construction constraints. This affects both the geometric characteristics of the track and the dynamics of the infrastructure. However, it ensures that high speed services can be fully integrated with other operations, so helping to make the best possible use of the new infrastructure.

Maximum speed on the new lines will be 300 km/h, and to avoid future capacity problems any slower trains must be able to run at a minimum of 80 km/h. Dynamic parameters have been chosen to ensure optimal passenger comfort within this speed range, while limiting overall maintenance requirements.

Maximum gradient has been specified at 1·8%, which is comparable with the 1·25% typically found on conventional mixed-traffic routes but considerably less steep than the 3·5 or 4% grades possible on lines restricted purely to high speed passenger services. The figure of 1·8% was selected following extensive traffic simulations to ensure that it was acceptable for both fast passenger and slower freight trains; adopting a steeper grade than 1·25% has given more freedom in selecting alignments and integrating structures with the environment.

To meet interoperability requirements and ensure sufficient power at high speeds, traction power will be supplied at 25 kV 50Hz rather than at 3 kV DC, the standard FS voltage. Use of multi-voltage traction units will enable seamless operation between the old and new networks.

Because of the time taken to obtain the necessary authorisations for building the various line sections and interconnections, the overall cost of the Torino - Milano - Napoli corridor has risen from 29000bn lire to 34000bn. This total comprises 27075bn for the actual lines, 5983bn for the stations and junctions, plus a contingency reserve of 942bn. We are confident that it will be possible to complete the project within the limits of this revised budget.

Milano - Bologna

The Milano - Bologna axis is a fundamental component of both the Italian and the European rail network. It handles around 25% of all freight traffic carried by FS - more than 20 million tonnes a year. Any growth above this figure is currently constrained by lack of capacity, as the existing double-track line is effectively saturated. In theory, the line can handle 250 trains per day. In practice, during peak periods it is already handling more than 257 passenger and freight trains a day.

Construction of the high speed line will create a four-track corridor, providing a 50% increase in capacity: 214 trains on the old line and 142 on the new.

The proposed high speed line between Bologna and Milano has a total length of 180 km and extends from Melegnano, to the south of the bridge over the River Lambro, to Lavino, east of the river of the same name, crossing a very substantial part of the plain of the River Po.

To avoid further occupying agricultural land in the Padane plain and to minimise the landtake of the new infrastructure, the alignment has been chosen to run as far as possible parallel to either the Milano - Bologna motorway or the existing railway.

Of the 180 km of new line, 130 km will parallel the motorway, with a further 10 km alongside the present main line. Separate alignments were adopted only where physical constraints made it impossible to keep the road and railway together - for example at the Po crossing. In some cases separate alignments were used to avoid visual intrusion of new rail bridges or viaducts next to motorway junctions and service stations. In other cases, for example at Modena, the new line has been routed to avoid populated and industrial areas altogether by looping around the town.

Around 87% of the alignment is on embankments, 11% on viaducts and 2% is in covered sections where artificial tunnels have been built for environmental reasons.

Eight interconnections will be provided to link the line with the existing network, so extending the benefits of high speed services to local and regional routes. Interconnections are situated at Melegnano, Piacenza (east and west), Fidenza, Parma, Modena (east and west) and Lavino. It is also planned to construct a new station near Reggio Nell’Emilia with both passenger and freight facilities; this will serve the central part of the Po valley.

Bologna - Firenze

Despite being the shortest of the new lines at 78·2 km, the Bologna - Firenze section has a very high proportion of complex civil engineering work. This includes 73·1 km in tunnel and 1·2 km on bridges or viaducts; a mere 3·9 km is either in cuttings or on embankments.

The line also presented the construction teams with challenging problems associated with the mountainous Apennine terrain and its extremely complex geological nature.

The line now being built augments a direttissima opened in 1934 from Bologna to Prato, itself bypassing a tortuous route through Pistoia.

It leaves the southern outskirts of Bologna on open ground, and crosses the Savena river on a short bridge. Soon after it enters the first of the tunnels, the 10850m Pianoro tunnel. It emerges at the deep valley of the River Laurinziano, crossed on a 126m viaduct, and then traverses the River Crocione on a box-girder structure. Next it enters the 3855m Sadurano tunnel, returning to the open air high above the valley of the River dei Cani, which it spans on another box-girder structure. This is followed by a short section in cutting, leading up to the 9243m Monte Bibele tunnel. At the end of this tunnel the line continues in the open, crossing the valley of the River Idice on a 126m skew viaduct, before reaching the north portal of the 10415m Raticosa tunnel - the summit of the line at 413m above sea level.

On leaving the tunnel, the line crosses the deep gulley of the Diaterna river, on a 91m viaduct. The next underground section, the Scheggianico tunnel (3558m), ends at the Santerno valley, crossed on a 73m viaduct. This marks the halfway point, and the San Pellegrino Traffic Control Centre is located here. There are emergency crossovers between the two tracks, sidings and train sheds for servicing and first-aid operations, along with a building for Auxiliary Services and the Electrical Equipment Service.

The line then enters the 15282m Firenzuola tunnel, from which it emerges in the Mugello plain. It then bridges the River Bagnoncino with another box-girder structure and disappears into the Borgo Rinzelli tunnel (717m). After crossing the Scarperia - Borgo San Lorenzo road and passing through the 654m Morticine tunnel, the line commences its longest stretch in the open, over 1 km, to cross the Sieve plain. The Sieve river is crossed by a viaduct spanning 635m.

The northern entrance of the Vaglia tunnel, about 18 km in length, is situated at the end of this stretch. The line then continues briefly in the open to Castello station on the outskirts of Firenze, where it joins the conventional network.

Among the civil works already in progress on the Bologna - Firenze line in the Emilia Romagna region, the most interesting is probably the Osteria ’window’ near Monghidoro. This 143m access tunnel leads into the Raticosa tunnel on the high speed line, also accessed via the Castelvecchio bore starting near Firenzuola on the Tuscan side, of which some 373m have already been completed.

Firenzuola is also the site of the Rovigo window, providing emergency access to the Firenzuola tunnel, of which 239m have already been excavated. The San Giorgio window, a third bore for access to the Firenzuola tunnel, is being excavated at Scarperia; about 255m had been completed by mid August.

At Cardetole, work is under way on the artificial tunnel section at the northern end of the Vaglia tunnel, which at 18 km is the longest on the route. Between Vaglia and San Piero a Sieve, the 422m Carlone window has already been completed to give access to the Vaglia tunnel, of which 161m have been excavated towards Firenze and 245m towards Bologna. Table II summarises the key features of the nine tunnels on the Bologna - Firenze line.

Roma - Napoli

The high speed line from Roma to Napoli entails the construction of about 220 km of new track. Heading east from Roma Termini station, the line first runs alongside the Roma - Aquila motorway and then turns south on a 4000m radius curve.

The line soon reaches its highest point, 370m above sea level approached on maximum gradients of 2·1%, and then crosses the hilly area of San Cesareo by means of the longest tunnel on the Roma - Napoli section, the 6619m Colli Albani tunnel.

Leaving the tunnel, the alignment enters a corridor shared with the Roma - Napoli motorway and the existing Roma - Casino - Napoli railway, thus reducing its environmental impact to a minimum. There are junctions with the existing FS network at Frosinone, Cassino and Caserta. The first two are designed for 160 km/h, while the third will permit trains to leave the high-speed line at up to 220 km/h.

The new line has an overall length of 204 km between Roma and Napoli and requires construction of a further 27 km of track in the form of junctions with the existing network. Embankments will form 38% of the route, cuttings 26%, viaducts 19% and tunnels 18%.

Construction work has begun at 54 out of a projected total of 67 sites. The route has been divided into 1049 lots, of which 514 are currently being worked on. Expenditure so far has amounted to 1735bn lire, about 31% of the estimated final total.

Colli Albani tunnel

The Roma - Napoli project involves construction of 710 separate structures, of which the Colli Albani tunnel and the 7771m Padulicella viaduct are undoubtedly the most complex and important. The twin-track Colli Albani tunnel (Table III) is 6619m long and is situated in the municipalities of San Cesareo, Roccapriora, Zagarolo and Labico in Roma province.

Emergency access galleries will be provided every 2 km, which will also facilitate maintenance work. These will further act as pressure relief ducts to counter the piston effect generated by trains passing through the bore at high speed.

Work on the Colli Albani tunnel is well under way and 5840m of the main bore have already been completed. Both access galleries have been finished and are currently in use by construction traffic to and from the main bore. Waterproofing work and the casting of tunnel lining components are also well advanced. o

CAPTION: The first major tunnel south of Roma on the new line to Napoli runs under the Albani hills. This picture was taken near the northern portal

CAPTION: The Milano - Bologna section of Italy’s TAV network will have interconnections to existing FS main lines at Piacenza east and west, Fidenza, Parma and Modena east and west. The line avoids the built-up area at Modena by passing well to the east of the town

CAPTION: Access ’window’ for the Firenzuola tunnel on the Bologna - Firenze TAV line will be available for emergency use once the line opens to traffic

CAPTION: Much of the TAV line between Bologna and Firenze runs in tunnel. This is the Osteria tunnel near Monghidoro

TABLE: Table I: Status of the Torino - Milano - Napoli route

Section Start of Construction Entry into

work time (months) service

Torino - Milan -- 58 2003

Milano - Bologna -- 58 2003

Bologna - Firenze July 10 1996 78 2003

Firenze - Roma 1970 264 1977-92

Roma - Napoli February 8 1994 62 2001

TABLE: Table II: Tunnels on the Bologna - Firenze route

Name Tunnel Maximum Total Average Constr.

length grade % ’window’ ’window’ time in

m length m grade % months

Pianoro 10 850 0·15 489 7·56 57

Sadurano 3 855 0·15 -- -- 60

Monte Bibele 9 243 0·15 1 547 9·70 56

Raticosa 10 450 0·15 2 473 11·85 70

Scheggianico 3 558 0·15 377 11·28 32

Firenzuola 14 282 0·15 3 553 11·39 57

Borgo Rinzelli 717 0·15 -- -- 25

Morticine 654 0·15 -- -- 25

Vaglia 18 497 0·15 402 12·37 70

TABLE: Table III: Colli Albani tunnel

Length of natural tunnel 6361m

Length of artificial tunnel at northern portal 250m

Length of artificial tunnel at southern portal 25m

Length of No 1 emergency access 270m

Length of No 2 emergency access 228m

Average lining thickness 80 cm

Average excavation section 135m2

Uniform grade throughout tunnel 1·7%

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