The Nicoll Highway collapse was a construction accident that occurred at approximately 3:30 p.m. Singapore Time (UTC+8:00) on 20 April 2004 in Singapore when a tunnel being constructed for use by MRT trains collapsed. The tunnel was part of the construction of the underground Circle Line, near Nicoll Highway station. The supporting structure for the deep excavation work failed, resulting in a 30-metre (100 ft) deep cave-in that spread across six lanes of Nicoll Highway. The collapse killed four people and injured three.