The electronic signs have been installed between the Bay Bridge and Carquinez Bridge. Each lane has a sensor that gives drivers information. A green arrow means traffic is flowing. The signs can also tell drivers when to change lanes because of a crash or stall and suggest driving speeds based on conditions.
Thursday's test was from 10:30 a.m. to 11 a.m. in Berkeley. More signs will be activated later this year.
Roughly 270,000 drivers a day brave a stretch of I-80 near Emeryville. Some drivers say their commute is miserable.
"Once you get in the city it's backed up all the way to the freeway," said Brian Everett, a commuter from Antioch. "Once you get on the freeway, it's backed up all the way to wherever you're going."
Far from just a nuisance, Caltrans knows it's dangerous.
"There are twice as many accidents here on 80 as on comparable corridors in Southern California," said SMART Corridor project spokesperson Ivy Morrison.
Later this year, Caltrans will activate more digital road signs.
"It's the most extensive system of its kind in the entire state of California," Morrison added. "We anticipate about a 10 percent reduction in travel times and also at least a 10 percent reduction in secondary accidents."
Still, some drivers take matters into their own hands.
"I try to take some shortcuts, they never seem to work though," Everett said.
ABC7 News asked Richmond commuter Stacy Sarkis if she's ever taken a shortcut off the freeway and driven down San Pablo Avenue. "Oh yes, and what's that like? Miserable," Sarkis said.
Caltrans has a fix for that too. The same computers that run the signs can extend the green lights on San Pablo and activate signs that route drivers back to the freeway once they've passed the accident.
Drivers are hopeful, though they know it won't solve the real problem.
"There's too many people and too many cars," Everett added.
Here's video of Caltrans testing its new digital freeway signs: pic.twitter.com/ZgJAQTNvzS— Jonathan Bloom (@BloomTV) September 3, 2015