Investigation Results Released: Crane Collapse on Rama II Road Claims 2 Lives, Blamed on Preventable Design Flaws
A crane collapse on Rama II Road in January killed two people, with investigators concluding the disaster resulted from improper fastening system installation and thermal expansion rather than material defects or natural causes.
On May 26, Deputy Secretary of Transport Jiraphong Theppituk, chairman of the fact-finding committee, announced the investigation results regarding the concrete beam and crane collapse on Highway 82 (Rama II Road), joined by Highway Department Director Piyapong Jiwattanakulpaisarn and State Railway of Thailand Acting Governor Anan Pothnim.
Jiraphong stated that on January 15, a massive crane used for bridge construction, along with prefabricated concrete components weighing several hundred tons combined, collapsed onto Rama II Road at kilometer 30+300 in Tha Chin Subdistrict, Mueang District, Samut Sakhon Province, while the public was using the route. Two people were killed and two injured.
The Ministry of Transport established a fact-finding committee immediately on the same day and appointed an engineering subcommittee comprising national-level experts led by Associate Professor Anak Siripanichkul, President of the Engineering Institute of Thailand. The committee held 8 main meetings and 4 additional engineering subcommittee sessions, conducting comprehensive investigations including:
– Site inspection of the accident location to examine damage firsthand – Collection of 21 documentary pieces from the Highway Department covering contracts, construction drawings, crane manuals, and safety reports – Testimony from 13 involved parties including the employer, designer, and contractor – Testing of concrete material quality in laboratory and field conditions – Structural analysis using computer modeling (Finite Element Method) – Systematic examination of all 7 hypothetical causes
After eliminating hypotheses through engineering evidence, the subcommittee concluded the root cause was not poor-quality materials, soil subsidence, or natural disaster. The collapse resulted from accumulated installation defects that eventually led to failure.
The bridge under construction had a slope, requiring the hundreds-ton crane to stand on this inclined surface. The contractor attempted to solve this by stacking 8 layers of steel plates over 80 centimeters high and adding a sand layer—comparable to stacking nearly 1 meter of bricks and placing heavy trucks on the sloped area. This resulted in incorrect crane fastening system installation, changing from the manual-specified Pin-Roller system (allowing thermal expansion) to a Pin-Pin system (completely locked on both sides).
Morning sunlight raised metal temperature approximately 8 degrees Celsius, causing thermal expansion. Due to both sides being locked, lateral pressure developed, pressing down on the stacked steel plates on the sloped surface. The steel plates began sliding off layer by layer rapidly, causing the crane's supporting legs to collapse and the entire crane to fall.
The committee found fault with both the contractor and the work supervisor. The contractor (Italian Thai Development Public Company Limited) improperly installed the crane fastening system, changing it from Pin-Roller to Pin-Pin without approval.
