A Lesson in Smart Solutions
A rapid and green transit network is at the heart of Nagpur’s transformation into a Smart City. In a bid to give the city its first Metro service, Mumbai Metro Rail Corporation Ltd (MMRCL) has commissioned the 41.7-km Nagpur Metro Project Phase I, with Afcons as one of the partners.
“We are executing Reach 2 (North South corridor) and Reach 3 (East-West corridor) of Nagpur Metro Project Phase I. Reach 2 comprises a 5-km double decker structure and 1.7-km viaduct starting at Automotive Square on Kamptee Road to Sitabuldi. Last November, MMRCL asked us to complete a stretch of about 600m between Zero Mile to Sitabuldi by February 2019 in order to commission Reach 1 by the first week of March,” says Amarsinh Raut, Chief Project Manager, Nagpur Metro Project, Reach 2.
As time was short, the site team along with the design team came up with smart solutions to ensure priority section was ready within three months.
Heavy Lifting in Record Time
At Sitabuldi, a 44m composite steel girder span had to be placed at the priority section over the busy Govari flyover. After the drawings were approved in November 2018, fabrication of 230T composite girders, including procurement, was achieved in a record time of 45 days in Pune. They were transported to the site in just 12 days.
“As Govari flyover could not be shut for a long time, we had to be really quick. We deployed three cranes of 275T, 220T and 200T capacity to erect the steel girders using the tandem lifting method. We took just four nights to erect four steel girders, followed by concreting,” says Raut.
Owing to the time constraints, temporary bearings were used for the steel girder erection. The entire deck was lifted with six span jacks and the temporary bearings were replaced with the permanent ones in a single day. The span was lowered the very next day. The entire stretch was ready in the last week of February this year, well within the deadline set by MMRCL.
The Show Must Go On
As part of the fast-tracked activity, two piers had to be constructed on either side of a busy traffic intersection of Govari flyover. Keeping in mind the safety and space constraints, it was not possible to erect staging from ground level to support the pier cap formwork. The site team innovated by using brackets to support the formwork. The brackets were fixed at the top of the pier with the help of bolts, which helped in avoiding any inconvenience to vehicular traffic and pedestrians.
Also, in a bid to minimise wastage of reinforcements, the Reach 2 team introduced fusion welding machine to weld the cut pieces at site. The welded rebars were used as earthing bars in pile, pile cap, pier, pier cap and segments.
The Two-in-One Behemoth
In this section, Afcons is building a Metro-cum-flyover stretch over single piers. This is a unique exercise, and only the second such in the country. Afcons’ design team conceptualised a Double Decker Launching Girder in-house, and the fabrication of two such equipment was done in just three months.
“Double Decker Launching Girders give better productivity as compared to the conventional ones as the spans between two piers can be erected one after the other after the completion of one auto-launching cycle. We saved 1.5 days for every span, which would not be possible had we used conventional launching girders,” explains Raut.
Project File
Name: Nagpur Metro Project Phase I
Length: 41.7 kms
Afcons’ Scope: 17.087 kms (41%) in two stretches - Reach 2 (North-South corridor) and Reach 3 (East-West corridor)
Reach 2: 5-km double decker Metro-cum-flyover structure and 1.7-km viaduct from Automotive Square on Kamptee Road to Sitabuldi
