Rome Metro – where engineering meets art tender estimate of €2.5bn and there Rome’s Metro Line C is a fascinating project on many levels. was talk of the whole line being As the two TBMs mining the latest section were preparing commissioned early in 2013, rather than in 2015 as expected. to pass by the city’s famed Colosseum, Kristina Smith took a The earliest ambition for Line C was that it would cross the tour round site. city from the northwest to the southeast with almost 40 stations. One of the first signs of the of Line C on behalf of the City Intersecting twice with the existing tunnelling works underway of Rome. “The Colosseum has metro Line A and once with Line beneath the centre of Rome been completely monitored with B, it would reduce congestion in are the huge metal braces sensors for horizonal and vertical the city centre and improve air supporting some of the city’s displacement and vibration since quality and passenger journeys. The historic monuments. The Aurelian 2015.” line is Rome’s first driverless one Walls are braced either side This latest section of Line C and features technology such as with a system of shoring in two consists of just two stations, Fori platform screen doors. locations. Similar support is visible Imperiali and Amba Aradam, 3km Metro C’s package of works on the Church of Santa Maria of parallel tunnels and two shafts. encompassed six sections of line – in Dominica and the Pilot of Known as Section T3, it runs right T2 through to T7 (see Figure 1) and Aqueduct Celimontano. There are under – and through - Rome’s 30 stations, 19 underground. The others too. historical heart. original plan envisaged sections T4 Contractor Metro C, a The technical and logistical and T5 opening first, followed by consortium of companies challenges encountered here the remaining sections, although led by Astaldi, is mining two illustrate some of the difficulties the sequence has been revised over 6.7m-diameter metro tunnels the wider program of works has the course of the programme. 35m below the surface using faced: the need to protect Rome’s Sections T7 and T6a, running Herrenknecht EPB machines. ancient monuments; hugely from Monte Compatri in the When TJ visited site in early May, significant – and disruptive - southeast up to Parco di Centocelle one of the two machines had archaeological finds; a variety of opened first, in November 2014. stopped for a thorough health ground treatment; and changes to The second section – T5 and most check, 350m before it would pass the design. of T4 – from Parco di Centocelle closest to the Colosseum at a to Lodi opened in June 2015. distance of 15m in plan. And San Giovanni station, the first Rome’s Line C Ambitious plans is operational “We expect potential When the Metro C consortium interchange with Line A, opened in as far as San movements of a few millimetre,” won the contract for Line C back May 2018. Giovanni. The says Andrea Sciotti, director in early 2006, it offered both Currently section T3 is expected stretch from there of operations for Roma the lowest bid and the shortest to be open by 2021, according to to Fori Imperiali is now under Metropolitane, the organisation potential programme. Its bid price Sciotti. To date, funding for the construction. set up to manage the construction was €2.17bn compared to the line only as far as Fori Imperiali, the station close to the Colosseum has been secured, with design up to Venezia Station given the go-ahead. Metro C has submitted project finance proposals for a further section. As for Section T1, which T3 Stretch was never part of Metro C’s works, that has been on hold for a long time. According to Sciotti, the cost for the line so far to Fori Imperiali will be €3bn, €800m of which will be spent on Section T3. Sciotti suggests that some of the reasons for the price escalation compared to the time of contract award include archaeological problems 20 Tunnelling Journal ROME METRO – WHERE ENGINEERING MEETS ART and changes to the standard covering seismic design. Both San Giovanni and Amba Aradam stations, which is currently under construction as part of T3, have been moved to a greater depth and the alignment of tunnels to and from them changed accordingly since the early designs. This is because the archaeological layer of ground, containing multiple artefacts from Rome’s long history, was found to be deeper than expected here. These two stations have also been redesigned so that they can double as museums. San Giovani, which is already open, features archaeological finds from multiple depths and periods of history in glass cases which are part of the station. “San Giovanni gives the public the story of the site. We can take the train passing between the old strata. We can read the depth and historical age of different cultures, so we can read the story of the site from ground level to prehistoric age,” explains Sciotti. Amba Aradam station has around 2.5 bar at the bottom of supplied by H+E, have brought the Section T3 of moved location since the the excavations. Both the station muck out. Rome’s metro Line C runs though the preliminary design. It was first boxes, which are formed with As well as the visible above- historical heart of placed in Largo dell-Ambra diaphragm walls, and the shafts ground support to some of the city. Aradam and is now in Piazzale have been waterproofed. Shaft 3.3 Rome’s historic buildings and Ipponio, a public garden. The will provide space for a crossover structures, various sections of The depth of San ground treatment have been Giovanni and revised design sees the whole as well as access for maintenance Amba Aradam station contained in one box, and emergencies while shaft 3.2 deployed along different parts stations were rather than two boxes linked by will be a ventilation shaft. of the T3 section. Where the lowered to avoid tunnels. The linked design became “If there is trouble during tunnels pass under the Aurelian the layer of impossible when archaeologists operation of the train, the system Walls, which were built in the 3rd archaeological interest, shown vetoed the use of jet grouting is designed to automatically take century to protect Rome against here in red. because it could damage the train to the nearest station attacks, compensation grouting underground artefacts. and the ventilation system starts has been used to firm up the Ironically, the new position to push the smoke and the heat ground beneath the structures. was assessed to have lower in the opposite direction,” says The protection measures were archaeological risk, but once Sciotti. successful, reports Sciotti, with excavations were underway this The stretch of tunnel between around 5mm of settlement and no location revealed perhaps the shaft 3.3 and San Giovani station damage to the walls. most exciting finds of the whole was constructed using traditional Compensation grouting will also route. methods rather than by TBM. “We be used where Line C underpasses did a 3.3m micro tunnel first, did the Colosseo Station for Line B. Archaeological surprises radial injections to increase the Originally, the plan was for Line Metro C began construction of strength of the ground and then A to link directly into this station, the T3 section in 2013, with the enlarged the tunnel,” explains with a new section of station construction of Ambra Aradam engineer Daniele Ricci, who works constructed directly under the Station and shaft 3.3, which lies for Roma Metropolitane and is existing one. However, this design between San Giovani and Ambra responsible for the civil works. was rejected for two reasons, says Aradan stations. It began work on The two TBMs, Herrenknecht Sciotti. the second shaft, 3.2, between machines which have been busy First it would have caused Ambra Aradan and Fori Imperali building Line C since 2009, started extended disruption to Line B. stations and then excavation for boring in 2018 having been And second, the new site for the the station subsequently. refurbished. The stretch between station does not have any risk The water table in this area shaft 3.3 and Amba Aradam was or archaeological discoveries. is 6 or 7m below ground level, mucked with trains. From Amba “In ancient times, there was a leading to a water pressure of Aradam onwards conveyors, little hill in this area, the Velian Tunnelling Journal 21 ROME METRO – WHERE ENGINEERING MEETS ART Hill, which was removed around 1930,” explains Sciotti. So, the Fori Imperiali station will be 50 or 60m from the existing Colosseo one, with the two stations connected by a foot tunnel. Excavations for the station box for Amba Aradam station have revealed impressive archaeological finds. In March 2016, a 900 sq m barracks dating back to the time of the Emperor Hadrian in the 2nd Century AD were uncovered. This was followed by the further discovery of a luxurious villa belonging to a Roman military commander. The barracks, found 9m below ground level, includes 39 rooms off a long corridor and a central fountain. Some of the well-preserved elements of the Controversy “It’s also very difficult to H+E conveyors in buildings included a mosaic floor, Looking at the mainstream news understand which kind of artefact use on the Rome marble floors and wall frescos. stories relating to Line C, it seems you will find buried in the ground. Metro Line C. There was also a grave alongside that the technical challenges and If you find special things it takes the barracks containing 13 adult achievements of the engineers time to excavate.