The efficiency of Lean at work in the Nagpur Metro

Nagpur Metro Phase 1 consisted of two corridors, North-South and East-West, with a total length of 41.7 km. Of this, 17.087 km (41 per cent of the viaduct) was awarded to Afcons in the Reach 2 (North-South corridor) and Reach 3 (East-West corridor) stretches. Afcons executed the Reach 2 package in the North-South corridor, which consists of a 5-km double-decker structure and 1.7-km metro viaduct structure that starts from Automotive Square on Kamptee Road and ends at Sitabuldi. The double-decker flyover structure consists of two decks: flyover level and metro level. The decks are constructed with precast segments. The flyover level consists of two segments: spine and wings. The team adopted Value Stream Mapping (VSM) to improve the cycle time by ~50 per cent, from 28 days to 14 days. Some key interventions were: Improvement in sequence of construction operations allowing for simultaneously launching wing segments and launcher (after erection of three cantilever arms)Analysis of idle time to optimise use of trailers for transportation of both segments and wingsSimultaneous operations for wings alignment, shutter fixing and rebar fixingMinimising time at site operations through use of boom placer instead of stationary pump and higher grade of concreteUse of manlift for stressing to decouple working site and ground traffic.