November 13-16 2017 will see leading international specialists in the global tunnelling sector attend the AFTES Congress in Paris which will include a special one-day event on November 15th. Launched in 2015 by the International Tunnelling and Underground Space Association (ITA-AITES), the first two ITA Tunnelling Awards events attracted more than 450 attendees and 200 entries. Several months prior to this event, judges scrutinise these applications to select a list of finalists for each of the nine categories. One of these categories must be highlighted as it comprises mammoth projects with a budget over €500m. The major project of the year category must also be highlighted this year, because all the finalists have developed transportation projects in big cities.
Major project of the year finalists:
- Tehran Metro (Iran) : a high speed project
One immense project to be mentioned is the extension of the Tehran Metro: from the south east of Tehran, the line goes through the city center to end up in the North West of the city. Line 6 of the Tehran Metro will be 31.2km long with 27 stations. This tunnel project is one of the longest in Iran. Started in 2015, this “lightning-project” has ended a mere 22 months later, in 2017, and a special record was established with 800m of tunnel excavation completed within a week.
This huge construction project required 35 access tunnels to build the “NATM” part of the main tunnel and the volume of steel used in this project is 20x greater than the steel used in the constructing the Eiffel Tower.
As the line passes beneath city center, various instruments and processes were used to decrease the risks arising from surface/subsurface obstacles (24-floor building, bridges, other metro tunnels, aqueducts…): ground leveling points, building settlements points, convergence pins, extensometers, inclinometers, crack meters…
- Qatar Rail Metro (Qatar) : Tunnelling under sensitive structures
Tunnelling beneath city centers, beneath buildings and especially specific structures has emerged as an increasing concern in the tunnelling industry. The Qatar Rail Metro is one good example of efficient management of mining under sensitive structures. The Doha Metro includes the construction of twin bored tunnels and 31 stations. Planned to be operational in 2020, the elevated and at-grade rail network will be built in 2 phases. The first phase are the Gold, Red and Green Lines with the second phase including an additional Blue Line. Not only did the project see 20 TBMs burrow silently beneath the city without a hint of disruption to the population, but the twin-bore single track tunnels were constructed using EPB technology, in order to mitigate the risks related to surface settlements, collapse, rapid water ingress through karstic features, excavation under sensitive structures or below man-made sea water channels, with the application of face pressure. Cost: €16.2bn
- Delhi Metro Phase 3 Expansion Networks (India) : Safety first for “THE” mega project in India
“Safety First!” was probably the leitmotiv of the metro phase 3 expansion project in Delhi.
This project is one of the most ambitious underground construction work for India as it comprises of 106 km of tunneling with 34 stations having to cope with numerous technical challenges such as unforeseen geological conditions, densely populated areas…
For 5 years, and thanks to many safety initiatives, the accident occurrence rate has been reduced which has led to a Lost Time Injury Frequency rate (LTIFR) of less than 0.02 in Phase – III compared to 0.19 in Phase – II.
Internal monitoring through site inspections and safety management initiatives such as Safety Trainings, Weekly Site Safety Walk & Monthly Safety Review meetings, were organized in
When operational, the project will reduce vehicle greenhouse emissions to approximately 3.1 million tons per year. Fuel consumption will be reduced to 141,353 thousand litres/ year.
- Confederation LRT Line (Canada) : a delicate excavation
The Confederation Line is a state-of-the-art LRT system and Ottawa’s largest transportation infrastructure project since the building of the Rideau Canal.
The Confederation Line is a P3 project between the City of Ottawa and Rideau Transit Group (RTG) funded by the Canada Federal Government and the Province of Ontario. The tunnel spans 2.9 kilometers, is on average 15 meters below the surface and features three stations on the Confederation Line project – Lyon, Parliament and Rideau.
In all, the project comprises thirteen stations and a 12.5-kilometre route, with 10 kilometers running above ground and 2.5 kilometers underground. Three stations are located underground in the new downtown tunnel.
The main excavation challenge for Lyon and Parliament stations was the close proximity of the basements. The stations are 18m wide in between buildings, 20m apart. The construction process foresaw an excavation by stages in order to transfer the ground loads from the arch to the invert through the cavern support, avoiding the loads into the basements.