J108 - How to transfer a launch gantry

 

5 April 2023 - Preparation works underway for the launch gantry to be slid over to the other
trackway towards Pandan Reservoir.
Image by Alfred Yeo Chi Jin

With thanks to Alfred Yeo Chi Jin, a resident of Bukit Batok West for contributing these photos with regularity, we have been able to observe the process of transferring a launch gantry from one trackway to another. The transfer was completed over a course of several days by sliding the supports across a beam that helped to keep the gantry in place.

5 April 2023 - A close up view of the support beam that is used to slide the gantry over. Further
installation of the last beam segment to fully slide the gantry is underway.
Image by Alfred Yeo Chi Jin

5 April 2023 - A view of a completed support beam at the northern end of the gantry.
Image by Alfred Yeo Chi Jin

5 April 2023 - The gantry prior to the full shift taking place.
Image by Alfred Yeo Chi Jin

Hydraulic jacks are typically used to help slide the gantry and support legs across the support beam until the gantry has been placed in the correct location. Once it is slid across over the period of a few hours, inch by inch, final checks are conducted to ensure that the final position is as intended. Once cleared, the gantry is ready to begin lifting works for the subsequent span.

7 April 2023 - An aerial view of the shifted launch gantry.
Image by Alfred Yeo Chi Jin

7 April 2023 - A close up view of the shifted launch gantry.
Image by Alfred Yeo Chi Jin

7 April 2023 - A view of the gantry from street level.
Image by Alfred Yeo Chi Jin

7 April 2023 - A close up of the shifted gantry from street level.
Image by Alfred Yeo Chi Jin

7 April 2023 - The shifted gantry on the Pandan Reservoir-bound trackway.
Image by Alfred Yeo Chi Jin

7 April 2023 - A close up view.
Image by Alfred Yeo Chi Jin

7 April 2023
Image by Alfred Yeo Chi Jin

7 April 2023
Image by Alfred Yeo Chi Jin

7 April 2023
Image by Alfred Yeo Chi Jin

7 April 2023
Image by Alfred Yeo Chi Jin

Once the launch gantry begins lifting segments, the span seems to go up pretty quickly. A well oiled machine & lifting team can become rather familiar with the process and this helps quicken the time needed to lift a span. However, lifting is the "easy" part as post-tensioning works still need to take place after the segments have been lifted and aligned so that the span is able to remain suspended between the piers.

13 April 2023 - Launch gantry in position.
Image by Alfred Yeo Chi Jin

13 April 2023 - Most of the segmental box girders (SBGs) have been lifted into position.
This is the fifth span overall and the first span on the Pandan Reservoir-bound trackway.
Image by Alfred Yeo Chi Jin

13 April 2023 - An overview of the span. A typical span is approximately 12 to 13 SBGs long.
Image by Alfred Yeo Chi Jin

13 April 2023
Image by Alfred Yeo Chi Jin

13 April 2023 - The next pier north is a movement joint expansion pier, hence the crosshead is of
a different design. The height difference likely made it a less likely candidate for the transfer
of the launch gantry from the Tengah-bound trackway to the Pandan Reservoir-bound trackway.
Image by Alfred Yeo Chi Jin

We'd like to thank Alfred Yeo for sending in the pictures and permission to use them for this post. Likewise, if you see something or would like to let us know about upcoming or ongoing works near you, do feel free to drop us a line. We'd love to feature your shots and aren't afraid to credit you. You can find out more on the contact us page of the blog.

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