Stretch of Highway 101 in Santa Rosa remains among Bay Area’s most congested freeway segments

Motorists driving south on Highway 101 during the evening commute long have been accustomed to hitting a wall of red taillights when they reach the Santa Rosa city limits.

Starting around Hopper Avenue, the three-lane highway frequently is jammed at that hour with commuters, shoppers leaving Coddingtown Mall and others who have been tending to business in the city’s western additions.

A new study confirms what these folks already know, which is that the highway from Hopper to Baker Avenue south of Highway 12 is one of the most frustrating, time-sucking experiences along the Bay ?Area’s entire network of freeways.

For the second year in a row, the roughly 4½-mile stretch through Santa Rosa ranked 48th on the list of the region’s 50 most congested freeway segments compiled annually by the Metropolitan Transportation Commission.

The study found that motorists spent the equivalent of 570 hours in 2014 puttering along at speeds of 35 miles per hour or less during peak commute hours, from 3:30 to 6:15 p.m.

“A lot of people are getting off work and heading home and feeding into everywhere,” CHP Officer Jon Sloat said. “All of the major industrial areas around Santa Rosa are feeding in. And the Highway 12 intersection adds to congestion.”

The most congested Bay Area freeway segment in 2014 was along Interstate 80 from Hercules to Oakland. Motorists there spent 8,750 hours in congested conditions that year. Second on the list was the morning drive on southbound I-880 from San Leandro to Milpitas, followed by the afternoon commute on southbound Highway 101 from Fair Oaks Avenue in Sunnyvale to Oakland Road in North San Jose.

Another local stretch of Highway 101 that has earned a notorious reputation for bottlenecks, the Novato Narrows south of Petaluma, did not make the list of the Bay Area’s most congested freeways.

For motorists traveling through Santa Rosa, the good news is that things appear to be getting better. While the overall rank of the Highway 101 segment was unchanged from 2013 to 2014, the actual amount of time motorists wasted in traffic over that two-year period decreased by 120 hours.

That’s despite an increase in the number of vehicles traveling Highway 101 over the same period of time.

From 2012 to 2014, southbound traffic on the freeway increased by about 8 percent south of the Central Windsor exit; 10 percent south of River Road; and about 7 percent south of College Avenue, according to Caltrans.

Traffic south of River Road increased from an annual average daily number of 90,000 vehicles per day in 2012 to 99,000 vehicles per day in 2014. That includes vehicles going in both directions on the highway.

Caltrans expects the numbers will have climbed even higher in 2015, according to Allyn Amsk, a spokesman for the agency.

At the same time, traffic generally is flowing faster on the highway during commute hours, by about two to four minutes, depending on the time and location, according to Suzanne Smith, executive director of the Sonoma County Transportation Authority.

She and other traffic experts attribute the speed-up to ramp metering, which was first implemented on Highway 101 in September 2014 and now is in use on dozens of ramp locations.

“Instead of having a blob of cars enter the freeway at once, it’s like a zipper, where motorists merge onto the freeway and are better able to utilize the capacity of the freeway lanes,” Smith said.

The improved traffic flow on Highway 101 bucks the trend across the Bay Area region, where traffic congestion increased 3 percent in 2014 to an average of 2.7 minutes per commuter each weekday from 2.6 minutes in 2013, according to the MTC study. That was the Bay Area’s highest recorded level of congested delay on a per-commuter basis, and a nearly 40 percent increase over the figure of 1.9 minutes per commuter per day registered in 2010.

The study noted that freeway congestion around the Bay Area is increasing at a faster rate than either population or employment.

No major Highway 101 improvements through Santa Rosa are on the immediate horizon, which means motorists for the most part will have to endure current conditions.

A long-sought upgrade to the Hearn Avenue interchange is still years away, according to Amsk with Caltrans.

The $20 million project currently has enough funding for environmental review and design. But Amsk said the earliest construction could begin is 2019. The project is sponsored by the city of Santa Rosa with oversight from Caltrans.

Smith said given the constraints of construction work through the downtown Santa Rosa corridor and the costs of large infrastructure projects, “the answer to traffic congestion in the future is going to rely more on new technology, carpooling and transit.”

You can reach Staff Writer Derek Moore at 521-5336 or derek.moore@pressdemocrat.com. On Twitter @deadlinederek.