Work to build a bridge over the Weymouth Relief Road at the top of Ridgeway Hill will close one of the three lanes of traffic until the new road is open.

Signs will be put up on Tuesday to warn motorists that a section of the Ridgeway will be closed from Monday, May 11, for safety reasons.

Dorset County Council says part of the new bridge foundation is in the Weymouth-bound carriageway at the top of Ridgeway Hill, meaning that this section of the lane has to be closed.

Southbound traffic will be diverted into the middle lane to avoid the work.

The council’s head of highways Andy Ackerman said two-way traffic will be maintained at all times.

The relief road will be open by spring 2011.