Preparatory work for a £1.6m scheme to replace a roundabout on Norwich's ring road will cause drivers disruption next week.

The roundabout where Sweet Briar Road meets Dereham Road is used by about 40,000 vehicles a day and is often clogged up with traffic at rush hour.

Council bosses agreed in January to an upgrade for the roundabout, which they say will ease congestion and pave the way for better bus services.

The approved changes will see the current roundabout replaced by a larger one and new pedestrian crossings installed. New 30mph speed limits would be introduced in parts of Sweet Briar Road and Guardian Road.

During the public consultation, 65 people had their say on the scheme, of which about a third, including Norfolk police, supported the improvement.

But there were a string of concerns raised. Almost a third of comments were concerns that, during and after the work, more traffic will use Hotblack Road and Waterworks Road.

The work on the roundabout, due to last more than six months, is due to start in August. But from Monday, May 8, there will be five nights, until Saturday, May 13, when temporary four-way traffic lights are in place overnight.

The traffic lights will be in place from 7pm until 7am each night, but they will not be in operation during the day.

That is so that a highway drainage survey, including cleaning of gullies and pipes, can be carried out.

Engineers will also conduct a survey of the utilities which run near the site, including detection of underground utility cables and pipes.

The work is part of the wider Transport for Norwich plan. That project, which includes the Norwich Northern Distributor Road, has also seen work in areas such as Westlegate, All Saints Green, Golden Ball Street, Tombland and Grapes Hill.