A new northbound Highway 101 onramp at East Washington Street in Petaluma opened Wednesday morning.
Part of a $23 million overhaul of the busy interchange, the new onramp is expected to alleviate traffic on the congested East Washington Street overpass.
"It's exciting for the community," said Petaluma City Councilman Mike Harris, who is also on the Sonoma County Transportation Authority. "It's traffic relief that we have been wanting and needing."
Opening the new onramp eliminates a bottleneck for motorists, Caltrans officials said.
Westbound drivers on East Washington Street no longer turn left across traffic to access the existing northbound loop onramp. Instead, they merge right onto the new ramp behind the Raley's grocery store.
Eastbound drivers on East Washington Street will continue to use the northbound loop onramp.
Petaluma police said there were no reports of traffic incidents at the interchange as of Wednesday afternoon.
Nancy Brocco, a Petaluma records technician, said a westbound driver in the left lane cut in front of her to access the new onramp.
"I didn't even realize it was open until I looked over and saw it," she said.
Caltrans in August estimated that the onramp opening would be as much as a year away due to the installation of rubberized asphalt, but later determined that the material was not needed.