The Singapore Civil Defence Force extracted three bodies from the site but were unable to retrieve the last due to unstable soil.

Heng Yeow Pheow, an LTA foreman whose body was never recovered, was posthumously awarded the Pingat Keberanian (Medal of Valour) for helping his colleagues to safety ahead of himself.

The CCL tunnels were realigned, with Nicoll Highway station rebuilt to the south of the original site underneath Republic Avenue.

[15][16][17] In 1996, the joint venture was investigated for breaching safety rules in a previous project; infringements included loose planks on its scaffolding.

[18] The site was on land reclaimed during the 1970s and consisted of silty old alluvium and a 40 m (130 ft) layer of marine clay resulting from sea-level changes of the Kallang Basin.

[19][20] The station and tunnels were constructed from the "bottom-up": cut-and-cover excavation was supported by a network of steel king posts, walers, and struts to keep the site open.

[27] All machinery was turned off as the SCDF used a life-detector device in the collapse site but nothing was detected and sniffer dogs were brought into the search.

[28][29] Prime Minister Goh Chok Tong visited the site on 21 April; he praised the coordination between the SCDF and the Public Utilities Board (PUB) for the ongoing rescue efforts and expressed relief at the small number of fatalities.

The SCDF had to vertically excavate through a pile of rubble and debris located within three cavities, two of which were flooded and blocked by twisted steel beams and struts.

The operation presented significant difficulty due to the limited space for manoeuvring within the cavities and the lack of visibility in flooded areas.

The LTA detected stability problems on 23 April at 1:05 am and grouting was implemented to stabilise the soil while water was pumped out from cavities, allowing rescuers to further investigate.

[21] While the surrounding buildings were assessed to be safe,[25] they were later monitored for stability with additional settlement markers and electro-level beams that were installed at the nearby Golden Mile Complex.

Senior District Judge Richard Magnus was appointed Chairman; he was assisted by assessors Teh Cee Ing from the Nanyang Technological University (NTU) and Lau Joo Ming from the Housing and Development Board.

[54] Because all parties involved would need two-and-a-half months to prepare due to complex technical content, the inquiry was postponed to 2 August.

[60] Nishimatsu's senior on-site supervisor Teng Fong Sin claimed ignorance of the significance of the trigger values taken from the retaining wall.

While he was also alerted to other ground movements, Nishimatsu addressed these cracks by applying cement patches, and no further corrective actions were taken because the buildings did not suffer any structural damage.

[65] According to a system analyst from Monosys, the project's subcontractor, the strain-detecting sensors recorded readings that were still below trigger values at 3 pm.

[61] LTA supervisor Phang Kok Pin, whose duty was to confirm the correct installation of support beams, said he visited the pit typically once or twice a day.

He conducted only sporadic inspections and heavily relied on reports from Nishimatsu contractors to confirm the accurate installation of the beams.

[77] To meet deadlines, Chikushi had accelerated the hacking of a wall that led to the removal of support beams in the excavation, and approved the grouting method that left gaps under some cables running across the site.

[78] The final phase of the hearing, which involved the consultation of experts on the causes of weakening of the retaining wall, began on 24 January 2005 and concluded on 2 February.

[79] The COI released its final report on 13 February 2005; it concluded the incident was preventable and had been caused by human error and organisational failures.

[81] The COI report said the "warning signs", such as excessive wall deflections and surging inclinometer readings, were not seriously addressed, and blamed the collapse on the contractor.

The money from the public donations was diverted into a trust fund that was set up by Heng's Member of Parliament Irene Ng from which expenses for his children's upkeep could be drawn until 2019.

A qualified person from LTA, who was project director of the CCL and responsible for monitoring the site's readings,[98] faced charges under the Building Control Act.

Safety requirements are now set above industry standards, which include doubling scaffold access for evacuation routes in an emergency and one man-cage at each excavation area for rescuers.

[104][105] Under the Safety Performance Scheme, contractors are now offered incentives or penalties and are required to maintain a Risk Register that identifies all hazards.

[105][106] The contractors and LTA meet every six months over safety performances, and identify and mitigate potential risks during the progress of works.

[116] The LTA decided against rebuilding at the original site due to higher costs and engineering challenges posed by debris left there.

[104] On 29 September 2005, the LTA marked the start of the new Nicoll Highway station's construction with a groundbreaking ceremony,[123] during which the diaphragm walls were first installed.