Work is also under way to build a relief road from Dorchester to Weymouth
A public exhibition is set to open in Weymouth displaying information about a £9m Olympic transport project.
The scheme aims to help the town cope with an increase in traffic when it hosts the 2012 sailing events along with Portland.
Work will start from 7 June to redesign five roundabout junctions, including those in King Street and The Esplanade.
The public exhibition will be open daily at Weymouth library from 19 to 25 May, except on Sunday.
The Department for Transport grant will be used to replace traffic lights on the roundabouts on the King Street and Boot Hill corridor.
The signals will be designed to manage traffic flow and give buses priority at junctions.
David Diaz, Dorset County Council project manager, said: "It's a good opportunity for people to make themselves familiar with the new junction designs, as the first signalised junction will be open in six months time.
"There will be disruption to traffic during the construction of the junctions, but hopefully people will recognise that this short-term inconvenience is out-weighed by the long term benefits of the package."
Dorset will play host to 400 international athletes during the 2012 Olympic and Paralympic Games.
Sailing events for the Games are to be held at the new-look Weymouth and Portland National Sailing Academy.
In another project to ease traffic work on a £87m relief road is progressing between Dorchester, Weymouth and Portland.