Puerto Cabello-La Encrucijada Rail Line in Venezuela is 50% CompleteThe Ezequiel Zamora central railroad system in Venezuela connects, in its first stage, Caracas with the suburban Tuy valley towns, in particular the dormitory city of Cúa (see alignment in pink on map). The Tuy valley or Tuy Medio is a vast valley south of Caracas in Miranda state. President Hugo Chavez inaugurated that first stage of Ezequiel Zamora central railroad system on 15th October, 2006. This 41.4 km rail line includes 24 tunnels (20,378 metres in all), 27 viaducts and four stations (Caracas, Charallave north, Charallave south and Cúa). Read E-News Weekly 46/2006, 13/2003, 39/2002 & 4/2002.Further west, Ezequiel Zamora central railroad system will link, in a second phase, Puerto Cabello to La Encrucijada and then, in a third phase, La Encrucijada to Charallave in the Tuy valley, stretching for a total of 178.8 kilometres.The Puerto Cabello-La Encrucijada section is under construction and is expected to be operational in 2011. Italy and Venezuela signed in January a letter of intent for the construction of the missing stretch of the railway linking Caracas with Puerto Cabello. The intergovernmental agreement, signed by Venezuela's state railway autonomous institute IAFE and the Italian embassy, is for the construction of the 70 km-long La Encrucijada-Charallave stretch. The letter of intent is the basis for awarding the contract to an Italian partner which is expected to be the consortium of construction companies formed by Astaldi, Ghella and Impregilo, who also won the contract to build the other two sections of the Ezequiel Zamora railway system, Caracas-Cúa and Puerto Cabello-La Encrucijada.In the future, Venezuela's central railroad system will link Caracas, Charallave, Cúa and Puerto Cabello, stretching for 220 km in total. Benefits of the lineThe Puerto Cabello-La Encrucijada section, built by the Ministry for infrastructure through IAFE, forms part of the second phase of Ezequiel Zamora central railway system. It runs through the municipalities of Mariño, Alcántara and Girardot in Aragua region, and through seven localities in Carabobo state (Juan José Mora, Puerto Cabello, Naguanagua, San Diego, Guacara, San Joaquín and Mariara). This railway transport system will be well integrated to the road network, as well as to the main national ports and airports. It is an intermodal transport project both for passengers and freight. Once in operation, the line will benefit approximately 3.5 million people, in Aragua and Carabobo states. The traffic is estimated at some 40,000 passengers each day and 14.6 million per year and the line will also carry 11.3 million tonnes of freight annually. Some 6,470 direct and indirect jobs have been created, involving technicians, skilled professionals and workers, to construct this modern transportation network. The Puerto Cabello-La Encrucijada rail link represents a total investment of some VEF8 billion. Visit www.iafe.gob.ve and www.infraestructura.gob.veGeneral dataThe design and construction of the line that will link Puerto Cabello to La Encrucijada have been entrusted on 21st December, 2001 to Grupo Contuy, an Italo-Venezuelan consortium formed by Impregilo, Astaldi, Ghella Sogene and Otaola Ingeniería. Visit www.impregilo.it, www.astaldi.com, www.ghella.com and www.otaolagroup.comThe technical management, project control, engineering review, and the technical and administrative inspection have been commissioned by IAFE to the Ferrocentro consortium, made up of EICV, Inelectra, Systra and Beta Ingeniería. Visit www.eicv.com.ve, www.inelectra.com, www.systra.com and http://betaingenieria.comThe railway path stretches for 108.8 km and includes 15 tunnels of lengths ranging from 126 metres for the shortest to nearly 8 km for the Barbula tunnel, making a total length of 33,477 lineal metres. The bored cross-section is 88.60-108.04 square metres. In addition, the construction of 33 viaducts or bridges (24.73 km of viaduct in all) is under way and the line will serve seven stations.The complex orography and the lack of existing infrastructure in the Aragua and Carabobo regions have presented a substantial logistic challenge to access and supply adequately the many construction sites. About 50% of the construction of the Puerto Cabello-La Encrucijada line was finished as of 15th January, 2008. GeologyThe geological formation along the route of the tunnels mainly consists of metamorphic rock like gneiss, schists and amphibolites. The amphibolites are not or little weathered, the gneiss feature different grades of meteorisation and the schists are moderately to highly meteorised, with intrusions of calcareous rock. In general, there has been little presence of water throughout tunnelling.TunnelsThe construction of the tunnels is required by the existence of a rugged topography in the 37 km area located between El Palito refinery and Barbula, in Carabobo state, and by the necessity to provide a low gradient route through the mountains, as outlined in the project design. The tunnels cross the mountains without impact on the environment and the habitat in this area. Breakthrough of the Corona tunnel in October 2007 As of 31st January, the overall advance rate of the tunnels was 65%. To date, six tunnels are fully excavated and concrete lined (La Cabrera, Tapa-Tapa, Pastora, San Joaquín, Guacara and Pequeño). Concrete lining or excavation is under way in the remaining nine tunnels.Among the tunnels still to be excavated is the 7,702 m Barbula tunnel, between Las Trincheras and Naguanagua. It is now 35% completed. Engineers estimate the tunnel will be the last to be finished, in 2010, due to its long length and topographical complexity. The other tunnel under build is the 2,993 m Guaremal tunnel, between the regions of El Cambur and Las Trincheras. It is now 50% completed. To know the main technical data of all the tunnels and the advance rate for concreting works, view a table here.Excavation of the 5,242 m Corona tunnel ended on 16th October, 2007 when the last fraction of rock separating the two drives fell down inside the tunnel. This is the third longest among the 15 tunnels under construction on the line. It was built by two crews of workers from the north and south portals.Tunnelling methodsThe tunnels have been excavated using conventional methods and, in view of the numerous work sites, a wide range of the main well-known techniques has been employed. Some tunnels have been drilled and blasted while excavators supplied with hydraulic breakers have been operated on others. Some tunnels also required reinforcement of the face and/or contour of the cavity.In the case of drill and blast tunnelling, two- or three-boom jumbos fitted with powerful rock hammers have bored holes into the rock and explosives have been placed in the holes and the site blasted. Where mechanical systems are best suited for the rock excavation, crews use suitable hydraulic breakers mounted on powerful excavators.Blasted rock or softer ground is loaded by wheel loaders into dumper trucks able to drive in rugged terrain to the disposal sites, in full compliance with the most stringent environmental and safety requirements.Where the best conditions are encountered, the permanent reinforcement involves fibre reinforced shotcreting and/or occasional or systematic rock bolting of the crown. In poorer rock conditions, the first phase support involves steel arches, welded mesh, shotcrete and bolts. In addition, when needed, glass fibre rods and/or forepoling reinforce the tunnel face and ensure ground stabilisation.The project plans involves placing a final concrete lining once excavation is completed, in general reinforced concrete produced from plants installed near the work sites. View pictures here.Latin America's longest railway tunnelThe Barbula tunnel will be Latin America's longest railway tunnel. It is the eighth tunnel in the Puerto Cabello-La Encrucijada direction among the 15 tunnels spread out along the line. It is a tunnel mined in some of the most difficult ground conditions. Its peculiar geology is characterised by clay and alluvium which require special ground improvement by jet grouting to solidify the soil mass and ensure impermeabilization of water bearing soils prior to tunnel excavation.Skilled crews work 24 hours per day in three shifts of 15 tunnellers, along with foremen, mechanics, machine operators, drivers, and electricians. Nearly 12 hours are necessary for each excavation cycle. The first step is the drilling of the blast holes by a Boomer drill rig, which takes two and a half hours. The geologists prepare the drill pattern, which indicates where the holes have to be drilled prior to charging the explosives, a task that takes another two hours. The blast phase lasts 40 minutes.Once the area is detonated, a waiting phase is necessary to enable gas dispersion. Finally, four hours are necessary for the dump trucks to make runs to haul rock, debris and other spoil out of the tunnel and on to dump sites elsewhere. The last step is the final concreting to line the tunnel with a smooth and perfect concrete ring. Read E-News Weekly 49/2002 & 5/2002. 07/08.