Kio Avenue 5 and Changi Village. Localised chokes in the drainage along Airport Boulevard, Ang Mo Kio Avenue 5 and in Changi Village were blamed for the floods. Lanes along Airport Boulevard and at the junction of Tampines avenues 9 and 12 had to be closed for one to two hours. A partially completed bridge at the Punggol Waterway collapsed under the weight of rainwater on Sunday morning. The eastern area around Changi and Pulau Ubin received the highest rainfall. As of 31 January 2011, 200.8mm of rain had pelted down on Pulau Ubin, and 178mm in Changi. The rain had subsided by Monday evening. Wednesday, 4 May 2011 Heavy rain caused flash floods in several areas including Ang Mo Kio Avenue 1 and Bishan Street 13. About 90mm of rain fell in less than an hour from 3 pm, said the Public Utilities Board (PUB). The floods subsided in about 20 minutes. Wednesday, 1 June 2011 Torrential rain caused flooding at the junction of Novena Square, a tree to fall elsewhere and claimed the life of one victim when a boy fell into a swollen drain along Whampoa. Despite the drain being guarded by a railing, the boy is believed to have stepped through a break in the railing at the flooded junction of Martaban Road and Minbu Road. He fell into the submerged drain, which is about 1.2m deep. The strong currents swept the boy away, causing him to drown. Sunday, 5 June 2011 A torrential downpour that lasted several hours early on Sunday morning triggered flash floods across several parts of the island. Senett Estate, Potong Pasir, MacPherson, Toa Payoh, Bukit Timah and Orchard were the areas hardest hit by the floods. Tanglin Mall, Forum Galleria and Traders Hotel were affected by the flood and partially flooded. St Regis Residences had its basement carparks flooded as well. Previous flood affected shopping malls in June 2010, Lucky Plaza and Liat Towers were not affected as flood barriers were activated at the start of the downpour although some shops were still partially affected. Tanglin Mall and St Regis did not receive flood alerts from the PUB which was due to a technical glitch in the flood alert software, which PUB will rectify. PUB also explained the flooding to the buildings are due to a heavy rainfall directly into the basements and the buildings' internal drainage pumps unable to cope