The Bellam Boulevard offramp, where local traffic converges with commuters headed to the Richmond-San Rafael Bridge, will be changed from three lanes to four.
Planners are working to weed out weaker options in an effort to streamline environmental review of a proposed connection between northbound Highway 101 and eastbound Interstate 580 in San Rafael.
The project, estimated between $192 million and $315 million, would create a new freeway connector allowing northbound Highway 101 drivers to merge directly onto eastbound Interstate 580.