Preparations are being made to close all the roads surrounding Sheffield City Hall, the conference’s main venue, and a fence has also been put up around the area.
Only busy West Street, to the rear of the city hall, will remain open during the conference, while nearby Leopold Street and Pinstone Street will be closed “if necessary”.
The fence has been installed at the request of South Yorkshire Police as part of measures to control any unrest which may occur as a result of the Liberal Democrats’ gathering, which will run until Sunday.
As many as 1,000 police could be on duty over the weekend amid expectations thousands of protesters could attend the event which it is estimated could cost £2m for policing.
Sheffield-based contractor Betafence, which has a factory in the city’s Shepcote Lane, has provided the temporary barriers, which are marketed under the brand name Publifor.
A spokesman for the firm said: “This type of fence has previously been used outside the European Parliament in Strasbourg and at the G8 summit in L’Aquila, Italy in July 2009.
“It is also currently used at sporting stadia across continental Europe including the Olympic Stadium in Rome, the San Siro in Milan and the Udine Stadium in Turin.”
It stopped people attempting to gain unauthorised entry into areas either on foot or in vehicles and helped to control large crowds.
Last night, the South Yorkshire Passenger Transport Executive announced that buses would be diverted in Sheffield city centre to cater for the road closures.