A traffic infrastructure renovation at the intersection of Gilman Street and Interstate 80 has moved closer to realization after Caltrans approved a proposed double-roundabout design to address chronic traffic problems and a high number of accidents and complaints.

The proposal includes two roundabouts, circular intersections in which incoming traffic yields to traffic traveling around the juncture. This design reduces fatal traffic accidents by as much as 90 percent, increases traffic flow — leading to reductions in emissions and fuel consumption — and promotes safer pedestrian access, according to the Insurance Institute for Highway Safety.

Eight entry points currently lead into the intersection, which is regulated only by stop signs. Backups at the two intersections, at the east and west access points for I-80, are among the problematic interchanges in Berkeley and lead to a slowing of freeway traffic.

The project will now proceed to an environmental-impact study in order to assess the consequences of the proposed construction. The impact study and the engineering and design work will cost approximately $3.5 million, and the construction costs are estimated at $9 million to $10 million.

Funding for the roundabouts is contingent on the passage of Measure BB, an Alameda County Transportation Commission sales tax. If the measure is passed by voters, the environmental review would be completed by 2017. Engineering and design work would then be finished by 2018, followed by groundbreaking in 2019.

Dave Campbell, advocacy director for Bike East Bay, says that this project will help close the gaps in bicycle-lane access and that funding for bike infrastructure is often only available as part of a larger initiative. The project will include bicycle pathways enabling cyclists to more easily transition between North Berkeley and the Bay Trail, a series of pathways that circumnavigates the Bay Area’s shoreline.

“Voter support for (Measure) BB is so important, because it’s going to fund improvements like this,” Campbell said. “These old interchanges that were built 40 to 50 years ago need to be upgraded to modern safety standards.”

As of June 2014, Caltrans has listed 21 existing roundabouts within the California State Highway System, with 35 in active development and 64 in the planning stage.

Beth Bush, a business manager for Hawkins Traffic Safety Supply, a business located in the vicinity, is skeptical about its effectiveness.

“I drive it every day, and I know how to maneuver it because that’s part of this issue — familiarity,” she said. “There is a sign that says, ‘No left after 5 p.m. to 7 p.m.,’ but folks still make the left turn.”

In a press release, the city of Berkeley expressed a desire for the new design to act as a “welcoming gateway” to the city in addition to providing improved access to the waterfront and nearby recreation areas.