To save time and conform to the latest international technologies, the Delhi Metro will use 25-metre long girders on some of the elevated viaducts to be constructed for the ambitious Phase-III, work on which will begin after the Union Government approves the project.
Using 25-metre long girders in the Phase-III will save time as well as minimise the inconvenience caused to people during the construction of the project, which will see another 107 km of the national capital getting connected with the Metro.
Delhi Metro had used 25-metre long girders in constructing the Airport Express Corridor, which was completed in just 27 months. In the Phase-II, DMRC used 4-6 metre long girders for construction which takes more time.
“These 25-metre girders are precast in the casting yards, brought to the site on trailers and launched with the help of cranes which takes lesser time than the conventional segmental launching technique involving the use of launching girders,” DMRC spokesman Anuj Dayal said.
The use of the 25 metre girders will help DMRC expedite construction work in the stretches where the movement of trailers and cranes is possible.
Due to this, Mr. Dayal said, the number of traffic diversions and barricading on the roads will be of lesser durations.
For the construction of longer spans, which will come up over traffic intersections, the 25 metre girders will rest on specially designed pier caps cantilevering towards the tracks on both the sides, Mr. Dayal said.
Custom designed concrete decks will be put on the top of these pier caps to bridge the gap between the 25 metre long girders.
The Phase-III has been cleared by Urban Development Ministry’s Empowered Committee and the proposal is currently before the Group of Ministers. After getting the GoM’s nod, it has to be cleared by the Union Cabinet.
Apart from this technique, DMRC will also use steel girders on spans measuring 40 to 50 metres. Such steel girders have been used earlier in Phase II and Phase 1 at various locations, he said.
For curing of the civil structures to enhance their strength and durability, ‘sophisticated curing compound coating’ are also being explored as per international practices.
“Concrete of the quality of M-50 and M-60 will be used depending on specific requirements. The parapets on the elevated viaducts will also be much sleek and therefore, easier to handle,” he said.