The widening of Route 18 through Weymouth and Abington is neither on time nor on budget.

The project, estimated in 2013 to cost $37.6 million, is now expected to cost $77 million, said Patrick Marvin, a spokesman for the Massachusetts Department of Transportation.

In an e-mail, Marvin said bids for contracts were being accepted and work is expected to begin this fall. Work initially was slated to begin in 2015.