Saturday, 2 August 2014

Downtown Line 3 shafts

Some readers were wondering what are Prison, Stadium and PIE shafts. So thought it would be a good idea to explain in a post what these are and where they are located that more people may understand.

In essence, the three shafts are cylindrical-shaped shafts that are constructed from ground level down. Once excavation has completed, these are used to launch 2 TBMs twice, once for each bound in each direction. For instance, TBM A will bore the Expo bound track from the shaft to station 1. TBM A will then be brought back once that drive has been completed and relaunched for the Expo bound track towards station 2. Once the drives are completed, a cross-passage (emergency walkway that connects both tunnels) will be built within the shaft prior to it being back filled.

An exhibit explaining about the shafts on 11 July 2013 - DTL3 tunnel works commencement ceremony
Construction sequence

Contract 926 will utilise two of the three shafts - Prison shaft and Stadium shaft. Prison shaft is located near the prison in between Tampines West station and Bedok Reservoir station. From here, two TBMs are launched for their drives - TBM Lizzi and TBM Hayley by contractor CMC di Ravenna from Italy.

Stadium shaft is located near the Tampines Stadium, hence the name Stadium shaft. It is located between Tampines West and Tampines Central stations. From here, two TBMs will be launched - TBM Chloe and TBM Beatrix, also by CMC di Ravenna.

Location of Stadium shaft
02 July 2012
13 March 2013

Contract 923A is for the construction of tunnels between Tampines East and Upper Changi stations. This contract utilises the final shaft in DTL3 - PIE shaft. It is located at the PIE exit to Upper Changi Road East. From here, two TBMs were launched from the shaft for their drives to Tampines East station. The TBM shield skins were abandoned in-situ and new skins with the internal components assembled for their final drive towards Upper Changi station. The TBMs are named Hermes and Argo.

Location of PIE shaft
A few more details from a site visit


  1. Where is the map to show location of prison shaft?

    Is it in prison grounds?


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