The Coastal Road Project in Mumbai by Brihanmumbai Municipal Corporation (BMC) required 3.45 km twin undersea tunnels to be constructed, starting from Priyadarshini Park and ending at Girgaum Chowpatty. BMC awarded the construction of this Coastal Road to Larsen & Toubro (L&T).
L&T specially imported a Tunnel Boring Machine (TBM) Mavala with an excavation diameter of 12.19 meters, making it the largest TBM to be used in India. L&T was in a dilemma as their project was running behind schedule due to the ongoing Covid pandemic. As per their original linear plan, they were to dig a 25 m deep shaft and then assemble the TBM and gantries inside the shaft. This linear method meant that they could not commence assembly of the TBM and the gantries till the 25 m shaft was dug and ready. Moreover, assembly inside the 25 m deep shaft was costly, time consuming, and required very heavy crane solutions.
After the shaft was ready, the TBM parts were to be lowered one by one using a crane, and then the TBM would be assembled in the shaft. The planned Lifting, Lowering, and Assembling activities were time-consuming in nature. Also, a vast area of land was to be prepared for operations of the heavy crane. The cost of land preparation was substantial, considering its proximity to the sea.
Freight Wings was entrusted with the task of carrying out the execution. Scope of work included Transportation, Skidding, and Launching of the fully assembled TBM having L=12.5 m, Dia of 12.2 m. and a weight of approximately 1500 tons, and 3 Back-Up Gantries weighing 350 MT each, with dimensions L= 26 m, W=8 m, and H=9 m.
The scope of work also included transportation, inclining, tailing, skidding, launching and positioning of the Cutter Head Section of the TBM. The Cutter Head weighs 350 MT and has a dia of 12.5 m x 3.5 m width. Launching of all the above items was to be done in a 25 m deep shaft.
Freight Wings transported the TBM’s assembled shield with a concentrated load of 1500 MT by using 4 rows of 2.4 m wide self-propelled modular transporter (SPMT) from the assembly area to the launch ramp. The 12.5 m dia. assembled shields with concentrated load of 1500 MT over 7.8 m length were lowered by Freight Wings into the launch ramp, using their 2500 MT capacity customized Mega Lift Strand Jack system. The company utilized their own specialized equipment for this project, which included the following:
- 16 nos. of 345 MT Capacity Strand Jacks (Digitally Synchronized) powered by Power Packs.
- 2 Power Packs and 56 Axle Lines of Self-Propelled Modular Transporters (SPMTs).
- 154m Heavy Duty Skidding Girders with Skidding Shoes and Teflon Pads.
- 2500 MT Capacity Mega-Lift System, Tailing System, & Modular Tower Lift System.
Freight Wings achieved the momentous feat in spite of the pandemic-induced restrictions. Their ingenious solution and timely execution enabled L&T to multitask and finish the assembly and lowering of TBM in record time. It was a truly ‘made in India’ effort!