Officials from West Bridgewater and Rayham Park are beginning negotiations after the town accepted an offer from the facility to be considered a surrounding community for the proposed slots parlor on Route 138 in Raynham. West Bridgewater joins Taunton and Easton in being designated a surrounding community, which allows each to negotiate mitigation funds from Raynham for the expected additional costs of traffic and public safety needs if the slots parlor opens. Town Administrator David Gagne will be part of the town’s negotiating team along with Selectman Jerry Lawrence and Town Counsel David Gay. “I think we have a pretty good idea what we’re going to ask for,” said Gagne, who has said traffic congestion is likely to get worse on Route 106 and the section of Route 24 that runs through town. Any agreement negotiated with Raynham will have to be ratified by selectmen.