Lucknow (LKO): The city’s Metro-Rail project achieved another milestone on Sunday with the Lucknow Metro Rail Corporation (LMRC) beginning installation of pier caps on Metro pillars along Kanpur Road. The first cap was placed at Transport Nagar in the presence of CM Akhilesh Yadav who was the chief guest at a ceremony to mark the occasion.
Pier caps are concrete platforms upon pillars that support ‘U-girders’, a structure that in turn directly bears the load of Metro tracks. LMRC said that in first few days, the caps will be installed between 5am to 8am to cause minimum hindrance to traffic flow. Subsequently, the placement of pier caps and U-girders will be shifted to the 12 midnight to 6am slot. The chief minister said he would also like to be present when the first U-girders are installed in early May.
LMRC plans to install one pier cap per day. The time-taking process needs large 330 tonne cranes to lift the pre-cast structure from the ground and place it on top of the pillar. The actual lifting and placement takes only about 15 minutes, but setting up the crane in the right position takes about 6-7 hours. The cranes also occupy a large part of road, leaving little space for the traffic.
After placement of the cap, its alignment on the pillar takes another hour. A concrete mixture to connect the two structures is then allowed to dry for 2-3 days. On the fourth day, when concretization is complete, pre-stressing of concrete cables is done to make the structure more compact and reduce load size on the foundation.
LMRC said that once the caps’ installation gathers pace, placement of U-girders on top of pier caps will follow. A pier cap measures about 10×3.5 metre while U-girder measures 27×10 metre. Two parallel U-girders are placed between two pier-caps to make the support system for tracks in both directions. This structure between the 2 pier-caps is called a ‘span’.
BEARING THE LOAD
Total 244 pier-caps and 478 U-girders have to be placed on the entire priority section
Installation of U-girders to begin from first week of May
Traffic in Transport Nagar halted from 8.30am and 9.30am on Sunday due to CM movement and Metro construction
Most construction to be shifted during night hours to ease traffic movement
Installation of pier caps and U-girders is expected to be complete by March 2016
Pier caps would take 3-4 days to settle. LMRC to place one cap per day