Page 91 - CO April 2017 Full Issue

PROJECT FOCUS Please tell us about the extensive So, one cannot really model a crossing based groundwork that was undertaken before on what has already been achieved. We have, the actual tunnelling work. however, looked for precautions taken and At the outset, we had to select suitable problems faced in diferent river crossings as interaction designs and technologies for the successful well as projects that have been executed in delivery of the project. Te designing of extremely high water bearing conditions and this project was entrusted to specialised applied this to our own geological situation world-class design companies such as that we will encounter. ATKINS, SYSTRA and Tunnelconsult. We chose Herrenkeneckht Tunnel Boring Have any innovations been made as part Machines (TBMs) for this project, based of this project? on their track record in manufacturing We have done a number of innovations and machines tailor-made for specifc project have improved upon numerous processes requirements. Herrenkeneckht is also while planning the project. engaged in maintenance of the two TBMs Due to site constraints the TBM has to be deployed for the Kolkata Metro project. driven through Howrah Station in advance. We are working together to ensure fawless Tis is a delicate operation where the TBM delivery of the project, especially the under- can encounter difficulty in crossing the the-river stretch. diaphragm walls. We designed a “Sof Eye” KMRCL had carried out soil investigation of styrofoam replacing M-40 concrete. Tis work at the pre-tender stage for feasibility has worked extremely well. Tis is a frst highlights in India’s Metro infrastructure study. In addition to this, we carried out soil design of its kind attempted in India by our space before this? investigation work near the entire tunnel in-house design engineers. First thing that comes to mind is the sheer alignment, deploying foating barges and At Afcons, we follow the culture of scale of projects being envisioned. Te gap pontoons in the river portion. We have also continuous improvement through between concept and actual execution is conducted extensive condition surveys of innovation. shrinking rapidly. We have incorporated the buildings in proximity to the alignment world's latest and best practices in our before carrying out tunnelling. design and implementation processes thereby delivering savings in time, cost and What have been the surprises that the space. geological survey of river bed has thrown Our engineers have rapidly scaled up their so far? skills to utilise the best practices with Tere have been no surprises thrown so far minimum gestation. with regards to the geological survey of the Metro rail frst arrived in India as early as river bed. Te tunnels will be constructed 1984 with the north-south Kolkata Metro. along the safest layer below the river bed. But the rush for Metro infrastructure What are the eventualities that you are actually began afer its success in Delhi. anticipating in your journey under the bed It was the frst time in India that tunnels of river Hooghly? How have you equipped were constructed for Metro using TBMs. It yourself to handle these situations? changed the outlook and future of Metro We are not anticipating any surprises. construction in India. We expect a similar However, we are well prepared and have impact with the underwater tunnelling by taken all possible precautions and measures. What took so long for India to come up Afcons. We have a team of highly-experienced with a project of this nature? tunnel crew on board, should an entry into The experience of the existing Metro Does Afcons have projects similar to this the cutting chamber be required under high corridor in Kolkata and the success of in the pipeline, given that you are making hyperbaric pressures during river driver. In the Delhi Metro network contributed Metro infrastructure in several other cities the remote possibility of river water ingress, to the sanctioning of the second phase in India? the TBM is designed to shut down like a of the Kolkata Metro that will have the We have recently been awarded the submarine, for safe evacuation. underwater Metro tunnel. The tunnel, underground Metro projects in Ahmedabad. which runs underneath river Hooghly, is We have completed two underground Is the underwater Metro tunnel under aimed at connecting Howrah and Sealdah projects in Chennai Metro. It is a matter of the river Hooghly going to be modelled railway stations, two of the busiest railway pride for us that Chennai Metro Rail Ltd over similar projects in the world, like the stations in the world. (CMRL) chose us to takeover abandoned Tames tunnel or Sydney Harbour? underground projects. This clearly Each underwater crossing has its own Tis is a momentous feat in terms of Metro demonstrates the confdence we enjoy from challenges and diferent geological features. infrastructure. What have been the other various clients in the country. u APRIL 2017 |construction opportunities 93