Just two slender cords of concrete and steel cross the River Murray - between Blanchetown and the sea -leaving a major transport corridor at risk of blockage in emergencies.
According to Murray Bridge Councillor Andrew Baltensperger, the risk of an accident causing disruption is too great.
"If something big happens here, it basically shuts Adelaide off from Victoria," he said.
"Last month we had that dreadful accident and that basically proved it - the Swanport Bridge is very narrow and there's nowhere to go if anything goes pear-shaped."
Traffic was banked up for kilometres along both sides of the Murray Bridge on June 16 after cars and trucks were diverted away from the scene of a fatal accident on the Swanport Bridge.
Authorities restricted traffic on the old bridge to one direction at a time that night, as repair work on the overpass needed to be done.
At a council meeting on Monday night, Cr Baltensperger said it was time to investigate whether there was a better alternative for traffic management if the Swanport Bridge was closed.
Councillors voted 8-1 in favour of asking the State and Federal governments whether there was any prospect of the old bridge getting an upgrade or construction of a new bridge around the city. Cr Baltensperger told The Standard he would like to see the Swanport Bridge widened to four lanes, ideally in the next few years, though he was quick to add the disclaimer "I'm no engineer".
A proposal to build a third road bridge was mentioned in a 2007 urban growth plan prepared for the council.
A map showed the site of a potential third bridge across the river located between the RSL, on the east side, and Mannum Road, near Thomas Foods, on the western side.
The idea was not mentioned anywhere else in the document, but it resurfaced in the council's 2013 town centre traffic plan.
"This crossing (would) allow an opportunity to relocate heavy vehicle movements from Adelaide Road, thus allowing Murray Bridge to focus on a more cosmopolitan feel by reducing the width of Bridge Street and promoting a pedestrian-activated space," the 2013 plan stated.
The old Murray Bridge is owned by the State Government and the Swanport Bridge by the Federal Government.
Each bridge carries between 2000 and 10,000 vehicles per day, according to the Department of Planning, Transport and Infrastructure.
The only alternative river crossings within a reasonable distance are the ferries at Mannum and Tailem Bend, which have load restrictions.