Workmen have been seen reinforcing the barriers on the Old Tram Bridge after it was closed earlier this week.
Lancashire County Council said there were a number of concerns over the structure of the bridge which crosses the River Ribble into Avenham Park.
On Wednesday, barriers were put up and pedestrians and cyclists told to use an alternative route to cross the river as the Old Tram Bridge was not safe to use.
The footpath which runs underneath the bridge on the south side of the river was also closed for safety reasons and people were advised to use the Viaduct Bridge.
Now the men in hi-vis jackets have been seen putting additional barriers at either end of the bridge.
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A spokesman for the county council said there was no further update on when the bridge would re-open to the public.