Probe into collapsed bridge walkway

Much of Durban’s infrastructure is aging and crumbling – highlighted this weekend when a pedestrian walkway linked to one of the city’s busiest routes over the Umgeni River collapsed.

However, the eThekwini municipality has committed more than R1 billion a year to managing and upgrading roads, bridges and other infrastructure.

Yesterday, the eThekwini |municipal engineering head, |Adrian Peters, told The Mercury the collapse of the Ellis Brown Viaduct, which crosses the Umgeni near the Blue Lagoon, was symptomatic of a bigger problem; much of the city’s infrastructure was reaching the end of its life cycle. The Ellis Brown Viaduct was built in the 1950s.

“Old bridges are not necessarily a problem but they should be inspected regularly. We are so close to the sea and the environment is very corrosive,” said Peters. “In this case though we do need to establish what went wrong.”

The cause of the collapse would be investigated but vandalism for scrap metal has not been ruled out. That part of the bridge was also very exposed to the elements.

“Impact from a vehicle appears unlikely,” he added.

Peters said the entire east side of the bridge was being isolated with concrete barriers.

Both of the traffic lanes would be open today.

An in-depth report would follow as soon as an inspection had taken place.

The cycle lane on the opposite side of the bridge had |recently been revamped.

He had been assured by the city’s structural engineers that the road bridge for cars was “perfectly safe”.

Peters said a complete inspection of roads was done every two years and road structures, such as the bridges over the Umgeni, were inspected |annually.

“Some infrastructure across all service areas has reached the end of its life cycle. We are monitoring the situation closely to ensure that we have a renewal programme that minimises the risk of failure. This failure is quite perplexing,” he said.

Peters explained that the beams supporting the pedestrian bridge that collapsed were connected to the main bridge by a mechanical linking system.

The original links were made of a brass alloy. Where they were corroded they had been replaced by a stainless steel alternative.

“As far as can be recalled, the area in question was one of the zones most recently replaced, but this still has to be confirmed. The only way that the beams could have fallen over is for these links to have failed for some or other reason,” he said.

“The Durban climate and environment is not very conducive to steel structures.”

There are at least four bridges that cross the Umgeni River in the Durban area. These include the N2 Umgeni River bridge, Ellis Brown viaduct, Connaught bridge and the Athlone bridge.

“Bridges can theoretically stand forever but may collapse when the design conditions change such as overloading or if affected by a natural disaster or accidental damage.”