San Eduardo Tunnel Under Construction in EcuadorThe San Eduardo tunnel project is located in the northwest part of Guayaquil in Ecuador. The length of the twin bored tunnel is 2 x 1.29 km. The tunnels will distribute traffic between Avenida de los Bomberos, Via Daule and Avenida Carlos Julio Arosemena. Construction of the tunnels commenced on 24th July, 2006. Tunnelling is expected to conclude at the end of this year. The project should be commissioned in July 2008. The geology consists of sandstone, breccia, greenish and calcareous siltstone. The rock is of very good quality (RMR of 83 and RQD between 90 and 100%). More than 200 workers and technicians are working on the project. The tunnels are being driven from four attacks. To dig the tunnel, the new Austrian tunnelling method is used in a top heading / bench sequence by means of drilling and blasting, with a computerized Sandvik Tamrock three-boom Axera T-11 jumbo on each drive (four in total). The machines drill horizontal blast holes, of about two metres, in the tunnel face. The next steps consist of loading the explosives, triggering the subsequent detonation and hauling out the blasted rock. The rock is hauled away by means of a Hyundai 760 loader and five 10 cu m trucks. The excavated cross section is 66.7 sq m in top heading and 40.2 sq m in bench. The total cross section is 106.9 sq m. Each tunnel will accommodate three traffic lanes. The drilling tools are supplied by Sandvik. The dynamite is Goma-2 ECO, the detonators are non electric (detonating cord 80 gr/ml). The supplier is Maxam (previously UEE). All is manufactured in Bolivia. The supplier of the ventilation system is Industrias y Servicios El Tigre of Peru. Visit www.miningandconstruction.sandvik.com, www.maxam-corp.com, www.iys-el-tigre.com and www.hyundai-ce.comOnce the mucking-out task is finished, a worker operates again the Tamrock jumbo to drill this time various vertical holes, 4 m deep, around the contour of the face. A crew of workers then introduces 4 m-long 25 mm-diameter cement grouted steel anchoring bolts in the holes to fasten a layer of 150 x 150 x 7 mm welded fabric produced by the local market. This part of the process makes the tunnel safe and stable. Then, a robotized Sika PM-407 shotcreting machine and a PM-500, shared by the four faces, spray HP-25 concrete without fibres. From a control panel, the operator controls the nozzle that sprays the concrete that dries almost immediately on the tunnel walls. The steel mesh is then covered and sealed. The setting time takes an hour. There is also an Aliva manual shotcreter for emergencies. Sika also supplied the concrete admixtures (alkali-free setting accelerator Sigunit L480 AF, microsilica fume SikaFume and plastifier Sikament N100). The bolts are from the local market. The workers also install HEB-100 steel arches in the poor ground sections (RMR from 40 to 60). The steel arches are from IPAC and Centroacero (curved and short). Visit www.sika.com.ec or www.sika.ch, www.centroacero.com.ec and www.ipac-acero.comThe support tasks last five hours, half of a total cycle. After the inner support of the tunnel has been achieved (bolts, mesh and concrete), a new cycle begins with the drilling of horizontal blast holes. Each ten hours there is a blast in the tunnel. Two SkyTrack 6036 telescopic handlers and two Manitou telescopic trucks, with lifting height of 14 m, are also used at the four faces. Visit www.manitou.comAverage advance ranges from four to six daily metres. The contracting JV OHL-Semaica is working on four drives, two in the north and two in the south. The tunnel is 13 m wide and 8 m high. As of 8th March, 2007 progress had reached a total of 551.05 metres, divided as follows: 110.70 metres at drive 1; 44.40 metres at drive 2; 235.30 metres at drive 3 and 160.65 metres at drive 4. A total of 45,000 cubic metres of rock will be excavated. The predicted date for breakthrough in each tube is September 2007 and November 2007. Visit www.ohl.es and www.semaica.comThe two tunnels will be connected by transverse passages for escape, built every 300 to 350 metres, that will be fitted with gates built in special high resistance fireproof steel. Also, there will be a lay-by approximately halfway through each tunnel where cars affected by a breakdown or other problem will be able to stop while driven in the tunnels. The lay-bys provide a fourth lane and are 40 metres long.US consultancy Louis Berger, Tahal Group of Israel and Consultoría Técnica Cía. Ltda. of Ecuador are supervising the construction. Click ec/17. 12/07.