Circle Line When the
Circle Line (CCL) was initially planned, this station, tentatively named "Thomson", was planned to be a shell station. The station was to be opened only when the surroundings were more developed. The contract for the construction of rapid transit system facilities for Thomson station was awarded to
Taisei Corporation at a sum of . The station was later announced to be opened with the Stage 4 CCL stations in 2008 and was renamed to "Caldecott" through a public poll. The station opened on 8 October 2011.
Thomson–East Coast Line Caldecott station was first announced to interchange with the 22-station Thomson Line (TSL) on 29 August 2012. Contract T213 for the design and construction of the TSL platform and associated tunnels was awarded to
Samsung C&T Corporation at a sum of S$285 million (US$ million) in July 2013. Construction started in 2014, with completion initially targeted to be completed in 2020. On 15 August 2014, the
Land Transport Authority (LTA) announced that TSL would merge with the ERL to form the TEL. Caldecott station, being part of the proposed line, would be constructed as part of TEL2, which consists of six stations between
Springleaf and Caldecott. The station was the terminus of the TEL before the line extended to
Gardens by the Bay station. Originally slated to be completed by 2021, however due to the
COVID-19 pandemic, the restrictions imposed on construction works led to delays in the TEL line completion, and the date was pushed to 2022. To facilitate the construction of the interchange station, Exit A of the station was permanently closed from 15 November 2020. Due to the mixed ground conditions of soil and rock and the presence of groundwater, the TEL tunnels at Caldecott station were mined instead of the cut-and-cover method. This construction method also minimised disruption to a service road connecting to St. Joseph's Institution International school. About of rock was removed via electronic rock blasting. On 14 December 2020, it was announced that the opening of TEL 2 was delayed to the third quarter of 2021 so the rail system software for the line could be reviewed. As announced during a visit by Transport Minister
S. Iswaran at Caldecott station on 30 June 2021, the station began operations on 28 August 2021. Prior to opening of phase 3 of TEL, trains turnaround by using the cripple
siding on the south end of the station. ==Station details==