ACCIONA, which will construct Line 1 of the Metro de Quito (Ecuador), is preparing one of the three tunnel boring machines (TBMs) at its heavy plant depot in Noblejas (Toledo) that will construct the Ecuadorian capital’s first metro line.The other two tunnel boring machines will be prepared and checked in Germany.
The machine itself is 9.3 metres high (equivalent to a three-storey building). It weighs approximately 1,660 tons and is capable of boring through the earth at an average speed of between 15 and 18 metres per day.The tunnel boring machine (TBM) will excavate a 4 km section, advancing non-stop 24 hours a day.
ACCIONA’s managers in Noblejas are carrying out tests on the TBM to check that it is suitable for the geological conditions at the site (materials, hardness…) and for the altitude and atmospheric pressure in Quito, among other variables.Once the tests have been completed, the tunnel boring machine will be dismantled and then shipped and reassembled on site at the entrance to the future tunnel of the Metro de Quito at the end of 2016, before beginning work in 2017.
A total of three tunnelling machines will construct the 22 km and 15 stations of Line 1 of the Metro de Quito.Two machines will be checked and tested in Germany before being sent to Quito, in addition to the TBM that is being prepared in Noblejas.
Excavating tunnels is one of the most complex challenges in civil engineering and can be done using various methods (mechanical, TBMs, conventional explosives…). However, the use of TBMs such as the one in Noblejas is the fastest and safest approach as it is ten times faster and reduces inconvenience and incidents for residents (especially in urban tunnels such as the Metro) by avoiding the need for traffic diversions, reducing noise, etc.
It also minimises the risk to workers by fitting segment or lining rings (which form the internal structure of the tunnel and weigh up to 5.1 tons each) behind the shield section of the TBM, as the front section of the machine continues to excavate the tunnel.This means that the work is carried out without the workers coming into contact with the rock or soil at any time, minimising the risk.
In the case of the Metro de Quito, each 1.5 metre section that the TBM advances is fitted with seven ring segments that slot together to form the tunnel lining.
Quito City Council has awarded ACCIONA the contract to construct the metro for the Ecuadorian capital in a project estimated to be worth $1.538 billion (around €1.398 billion).The contract consists of the construction of the Metro’s first line, which will be 22 km long and completely underground, as well as 13 stations, which will join the two stations that ACCIONA has already constructed (after being awarded the construction contract for the first phase of the Metro).This line will connect the north and the south of the city of Quito with a travelling time of just over half an hour. It will have a capacity to transport around 400,000 passengers per day.
This metro line is the first part of a new public transport system for Quito.The project will generate savings of $50 million per year in fuel costs thanks to improvements in urban transport, with a subsequent reduction of 67,000 tons of CO2.The work to construct the Metro de Quito will provide employment for more than 2,300 people, of which 100 will work directly on each of the three tunnel boring machines used for the project.
ACCIONA has extensive experience of complex tunnelling projects.Its most emblematic tunnelling works include the 4.6 km dual Legacy Way tunnels in Brisbane, which cost AUS$1.5 billion (around €988 million), as part of a consortium with the Italian firm Ghella, and which won an award as an outstanding international project.
At present the company is also working in a consortium with Ghella to design and construct the 20 km twin railway tunnels for the Follo Line Project in Norway.This is the second and the largest of the four EPC (turnkey) contracts included in this project, and is Norway’s largest infrastructure project to date.
ACCIONA, as part of a larger consortium, recently won major contracts for metro works in Brazil, including construction of the Línea Este for the Metro de Fortaleza (Metrofor) in an initial project worth around BRL 2.3 billion (approx. €533 million), and two contracts for Line 2 of the Metro de Sao Paulo (three stations) for a total of BRL 704 million (€163 million) and BRL 565 million (€130 million).
Other major ACCIONA projects in this sector include the Bologna railway tunnels for the high-speed line between Milan and Naples (Italy); the Pajares tunnel in Asturias (Spain), the eighth longest in the world; and the northern tunnel of the M-30 ring road in Madrid, which will be constructed by the world’s largest EPB tunnel boring machine.