Overloaded vehicles frequently travelling on a bridge on Shenshan Expressway are to blame for the partial collapse of it on Sunday, according to the preliminary investigation.

No casualties were reported in the accident, but the bridge, which is about 500 metres from the Shenzhen end of the 280-kilometre expressway, collapsed after a lorry carrying more than 30 tons of goods passed over it.

"The lorry was designed to carry 10 tons of goods at most, but the actual load was 20 tons more than the limit," said a spokesman for Guangdong Transportation Group, which is responsible for building, operating and managing the cross-city expressways in Guangdong yesterday.

"We believe it was the overload of the lorry that caused the collapse, but the real reason is that the road has been seriously damaged by a growing number of overloaded lorries since the expressway was put into use a decade ago," he said.

The company sent out an expert team to investigate Sunday's accident and may announce the official results this week, he added.

The expressway, which links Shenzhen with eastern Guangdong's Shantou, two special economic zones, has witnessed busier traffic in recent years because of the booming regional economy.

According to an official from Guangdong Road Bureau surnamed Lin, nearly all the lorries running on the Shenshan Expressway are overloaded, the newspaper Southern Metropolis News reported.

They usually carry sand, steel bars, cement and all kinds of raw materials, said Lin. One truck they previously stopped, which was designed to carry 1.95 tons, actually had 40 tons of goods.

The problem could cut the usual 20-year lifespan of the expressway by half, he noted.

While the law enforcement department is not allowed to check vehicles travelling on the expressway, it can stop them at around the tollgate.

The final section of the Shenshan Expressway will be closed for nearly one month because of the accident.

(China Daily April 18, 2006)