Police are using emergency powers to close two Cambridge city centre roads.
It comes as Extinction Rebellion Cambridge begin a week-long protest, setting up a base at the roundabout between Trumpington Road and the Fen Causeway.
Police have been working with Cambridge City Council, Cambridge County Council and local transport links on ways to mitigate any disruption.
In order to ensure Cambridge city remains open for business, police are using emergency powers to close Fen Causeway and Trumpington Road.
Alternative routes have been planned for vehicles and buses and the police, city and county council are urging people to consider different ways of travelling for the week.
Pedestrians and cyclists will not be affected.
For Fen Causeway diversions are in place along Newnham Road, Silver Street and Trumpington Street (Highways are lifting the restrictions on Silver Street for the week).
Those wanting to travel along Trumpington Road will be diverted down Lensfield Road, Hills Road and Brooklands Avenue.
The route of Trumpington Park and Ride buses will be diverted, with some bus stops suspended and additional temporary ones added. There will be further information at all bus stops.
City centre businesses, colleges and other organisations close to the blockade have been advised so they can plan appropriate contingency measures.
Superintendent James Sutherland said: “We review all reports of protest both spontaneous and planned.
“We have to strike a balance between the need to allow peaceful protest within the city and the disruption that the protest itself causes.
“Whilst the protests are likely to cause disruption, we are working with our partners to mitigate this and the level of disruption caused by the protests will be constantly reviewed throughout the week.”