A car flipped on its side on the Central Expressway (CTE) yesterday morning, causing heavy traffic along a 5km stretch of the expressway.
Photographs posted on citizen journalism website Stomp showed motorists trying to push the black sedan back on its wheels.
The accident occurred in the direction of the Seletar Expressway, after the Jalan Bahagia exit.
At 12.11pm, the Land Transport Authority (LTA), through its traffic news Twitter account, advised motorists to avoid the first lane on the CTE, and said there was congestion until the Kramat Road entrance.
About 20 minutes later, the LTA tweeted that the congestion trailed back to the Merchant Road exit.
The Singapore Civil Defence Force said that it was alerted to the accident at 11.47am and dispatched an ambulance to the scene, but the driver, a man in his 20s, declined to be taken to hospital.
The police, alerted to the incident at 11.48am, are investigating the incident.