Caltrans plans to begin construction this spring on a new traffic roundabout at a busy Highway 101 interchange in San Rafael.

The project site is along the east side of the highway at Civic Center Drive and Redwood Highway. Traffic from Manuel T. Freitas Parkway and the offramp from northbound Highway 101 also will feed into the roundabout.

On Monday, the project team updated the San Rafael City Council on the project’s benefits and construction timeline.

“The benefits to the city of San Rafael is improved safety, improved traffic operation on the local street and improved bicycle and pedestrian mobility as well as an increased accessibility to the bus stops,” Daniel Cuellar, Caltrans project manager, told the council.

The project was infused with a $8.4 million state grant. Construction alone is estimated at $7.5 million. The total investment, including engineering and right-of-way acquisition, is expected to be $11.5 million, said Matt O’Donnell, spokesperson for Caltrans.

Construction is expected to begin in May and last six months.

Originally planned as a project to relocate an unsafe bus stop and make accessibility improvements for transit riders, the roundabout has become the centerpiece feature. The northbound bus stop is dangerous because it requires transit riders to cross freeway-bound traffic.The project would relocate the bus stop to Redwood Highway, which runs parallel to the freeway. A bus exiting the freeway would go through the roundabout to reach the stop. After picking up passengers, it would get right back onto the freeway.

“The roundabout was deemed a positive traffic control device for this location in order to maximize the quick use by buses so they would be unhindered, as opposed to a traffic signal,” said Matt Korve, an AECOM design engineer supporting Caltrans.

After several public meetings, Caltrans and city staffers met with bicycle groups whose members were concerned about limited bicycle protection through the roundabout. The plan has been updated in response.

One major change is the addition of a two-way pedestrian and bicycle path separated from traffic. The original plan called for only a one-directional path.

A retaining wall at the corner of Redwood Highway would be extended to accommodate the new bi-directional path.

Warren Wells, policy and planning director of the Marin County Bicycle Coalition, wrote to the council to support the project.

“This outdated interchange design is long overdue for a refresh, and we eagerly await its implementation,” Wells said.

However, he said the new two-way path that would be created by Caltrans does not extend south to the next intersection, meaning the path for southbound cyclists would end mid-block.

“The City will have to implement its own project to connect riders from the southern limit of the Caltrans project to at least the signal at Merrydale/Scettrini,” Wells wrote. “Although coordination with Caltrans may be a challenge, we hope that these two projects can be aligned as closely as possible, so as not to leave riders traveling through the area with an unclear path of travel.”

On the west side of the freeway, the southbound bus stop would remain between the southbound onramp and offramp. Stairs to Freitas Parkway would be removed, and an accessible path would be added. A refuge median would be added to the Freitas Parkway crosswalk.

All curbs and sidewalks in the project areas will also be upgraded to meet Americans with Disabilities Act accessibility standards.

Construction will be divided into seven phases. The project team said there would be some overnight construction that could include ramp closures.

The bulk of the work will happen during phase 3 of the project, when the intersection at Redwood Highway and Civic Center Drive is expected to be closed for about two months.

During the full closure, detour routes will be in place to bypass the construction. No dates have been set.

City Council members are pleased about the project.

“We’re so happy. We’re so looking forward to this coming forward,” Councilmember Rachel Kertz said.

“It will make the area much, much, much safer,” Mayor Kate Colin said.