An overpass on the Middle Ring Road in Shanghai is severely damaged when a truck overturned spilling its load of concrete piles on May 23, 2016. 

5 people have been detained after an overpass on the Middle Ring Road in Shanghai was severely damaged when a truck overturned spilling its load of concrete piles.

The weight of the truck and its cargo caused the surface of an overpass to tilt, leaving a gap between bridge sections of about 40 centimeters in places.

Zuo Tianfu is deputy chief of Shanghai's traffic police.

"When the truck reached the pile No. ZN835, the surface of the overpass tilted in the horizontal direction and the pre-fabricated tabular piles tumbled down from the truck, with some dropping onto the overpass surface and the ground below. The damaged road surface caused four passing cars to sustain damage. But there was no death or injury from the accident."

Those detained include the truck driver and the director of Shanghai Jianjing Logistics Company, which operated the vehicle.

The overpass was designed for cars and buses, with a maximum loading capacity of 20 tons to 30 tons.

The truck which turned over had an aggregate load of 100 tons.

Li Jun, deputy director general of Shanghai's Municipal Road Bureau, said the overloading was to to blame for the accident.

"As the Middle Ring Road is designed to be used by buses and cars, the loading capacity is lower than for other bridges and express highways. Trucks are forbidden on the overpass. The truck was seriously overloaded and two trucks were driving on the same side of the overpass, causing the accident."

It could take at least two weeks to repair the damage to the overpass, and the closure of the road is expected to seriously affect the public transport system.

The inner circle of the Middle Ring Road is still closed to traffic from the S5 Shanghai-Jiading Highway to the North-South Elevated Road.

Many commuters have chosen to take the Metro instead of driving to avoid anticipated congestion on some of the city's highways and streets.