and the construction workers, the successful completion of the station, and blessings for future commuters. The construction of tunnels between the City Hall and Raffles Place stations required the draining of the Singapore River. The contractor used the cut-and-cover construction method since the tunnels, which cross over one another, would pass through a shallow part of the river. The tunnel boring machine was launched from Empress Place, which is just by the river bank. Due to the acidity of the Singapore River, a layer of concrete was added to the concrete frame around the tunnels, with a waterproofing additive for the base slab concrete. The concrete frame was designed to prevent any corrosion and floatation of the tunnels. Due to requirements by the Ministry of Environment ensuring that the work site does not occupy more than 40% of the river width, the work would proceed in three stages. The cofferdam in the first stage occupied about of the river width from the riverbank at the Immigration Building site. However, this restriction led to a limited work area. The piles installation was hindered by the boulders in the river, which had to be drilled through. The works were close to the historical monuments of the Immigration Building and the Cavenagh Bridge. These two sites had to be closely monitored for any ground movement. Monitoring instruments such as inclinometers and levelling pins were used to detect any structural movement. There were concerns that the Cavenagh Bridge would not be able to absorb any significant strains with the settlement of the bridge's anchor blocks. Saddles, joined by prestressing cables, were placed on either side of the bridge to unload and loosen the links and bridge wedges. However, these wedges could not be loosened. Instead, other temporary supports were placed to relieve any stress on the bridge. After finding some cracks on the entrance façade of the Immigration Building, the contractors underpinned the columns at the entrance. The first stage of the construction was completed in May 1985, with a delay of seven months. To speed up the construction, the Environment Ministry agreed to lift restrictions on the work area. The rest of the construction was completed in one stage, taking up the remaining of the river width. The subsequent stage also used fewer piles with the mixed use of cut slopes. Installation of the 2nd stage cofferdam began in May and works were