Wednesday, 9 April 2014

Napier - Final Preparations

We go aerial at the NPR site today. Contract T217 oversees the construction of Napier station and the adjacent tunnels to Orchard Boulevard. The site has already seen repetitive sewer diversions around the junction of Napier/Cluny Road as mentioned in the previous update. The area south of the station where the launch shaft is to be located has been cleared as well. The site office is located at the western end of the site.

Contract T217
Napier station will be stacked and designed in-house by LTA, featuring 3 levels - Subway/Concourse/Upper Platform (B1), Mezzanine (B2) and Lower Platform (B3, RL82.55). The station has been designed with knock out panels for a future underground infrastructure to cut through the mezzanine level. 2 barrier-free entrances will be built on either sides of Napier Road.

Excavation of this station will be vastly relied on dynamite blasting. Due to the sensitivity of the area, noise barriers as high as 12m will be constructed around Gleneagles and MFA around the station site. The POB at Gleneagles will be demolished.

A launch shaft will be built south of the station to facilitate 2 launches by a single TBM. The TBM will be slurry-type. The lower northbound tunnel will be bored first. Upon completion of the upper tunnel, all TBM accessories will be retrieved while the shield is abandoned in situ. The upper tunnel will then be bored with a new shield.

A cross passage will be located along Sherwood road, behind the PRC's Embassy. Due to the semi stacked configuration of the tunnels, this CP will be constructed by excavation from the surface to a depth of 42m and an audit will be mined to link both levels of tunnels. The excavation site will be eventually capped and backfilled hence does not serve as an escape shaft.

Site overview of the station box (Looking SE)
Final power grid diversions along Holland Road (looking SW)
Pedestrian Overhead Bridge (POB) at the left corner will be demolished and reinstated
North-South view of the station box
Site for launch shaft (looking south)
Looking north to Cluny Road
Future Entrance A to be located on Gleneagles side (looking NE)
An upcoming traffic diversion would be in place for this junction when structural work commences
CP3 to be located at Sherwood Road
A road diversion and noise barrier will be put into place

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