Broken Adelaide overpass 'for sale' online

A damaged overpass that has closed a major road in Adelaide for three days has gone up for sale online - and pranksters are offering more than $100,000 for it.

A satirical eBay listing has sprung up for the bridge that passes over South Road, which has been closed since Wednesday morning because of the crumbling overpass.

Engineers are working to repair the overpass so that cars can return to the busy arterial road but it is expected to remain closed into the weekend.

The eBay ad describes the item as a "pedestrian bridge, only 7 years old" and lists the cost price at "$30,000,000" and its condition as "for parts or not working".

"We are pretty keen for a quick sale as the bridge is causing a couple of traffic issues so best offer gets it," the seller wrote.

"It would make a great farm bridge for getting those milkers across the creek."

A buyer asked if the bridge could be used for storing nuclear waste, to which the seller replied: "I think it is hollow, so should be good to go."

As of Friday afternoon the bridge had a top bid of $100,090.95, with $10.40 postage to anywhere in Australia.

eBay's rules state that a bid is a binding contract so users have to pay for any item they win.

However, it seems unlikely that the ad-maker has the authority to sell the bridge or the means to post it.

The closure of South Rd has caused major disruption for thousands of motorists, while local businesses in the affected area are losing trade.