Upgrade of Mannai Roundabout
- Project: Upgrade of Mannai Roundabout
- Client: JH construction
- Location: B ring road
Equipment/Machines used:
Crawler cranes, Mobile cranes, Manlifts, Scissors lifts, Excavators, Trucks, Loading shovels and back propping.
Scope of work:
The existing fly over roundabout demolished to allow for a larger intersection junction to be constructed. The work was of a criteria nature as the traffic flow going through the underpass had to continue as normal during peat road usage times.
How the work was executed:
The existing roundabout flyover was constructed from series of concrete box girders approximately 25m long x 1.2m wide x 1m deep each weighing 90 tonne.
It was decided to separate them and lift them as complete sections using a 300-tonne crawler crane. To do this the ends and middle of the beams were propped to ensure no movement would occur during the cutting process. Before the cutting work started a water/material-catching deck was suspended below the beams to ensure that live traffic could continue to move through the underpass during the cutting process.
The concrete girders were next separated by using floor saws and wire saws to free each section and suitable lifting points were provided. The lifting of the sections was done at night when the underpass below was closed.