Tina Manos was riding her bicycle back home to Eureka from the North Spit one Saturday when the side mirror of a passing pickup truck struck her in the back. She flew off her bike, hit the ground and was knocked unconscious.

Manos, a kinesiology professor at Humboldt State University who researches and teaches bike safety, was taken to the hospital and treated for a concussion, bruises and a broken rib.

"Thank goodness it wasn't worse," she said by phone recently. "I was wearing a helmet, and the helmet cracked. But it was traumatic for me."

She doesn't remember anything about the collision that happened nearly three years ago. She learned from the police report that witnesses had seen what happened, and that the man who'd hit her had stopped and been questioned by officers.

"From my understanding, it was a gentleman in his 80s and I think he had misjudged the distance," Manos said.

Proponents of a bill working its way through the state legislature say it could help drivers make better judgments and reduce the number of such passing-by collisions. SB 910 -- introduced by Sen. Alan Lowenthal in February, passed by the Senate and now awaiting attention on the Assembly floor -- would amend the California Vehicle Code to require a vehicle to give a bicycle at least three feet of clearance when overtaking and passing it on the left. The law currently requires that drivers pass to the left "at a safe distance without interfering with the safe operation" of the overtaken bicycle.

The bill also would amend the law to allow a vehicle to cross over the double yellow line -- if safe to do so -- in a substandard-width lane to give a bicycle that three-foot buffer -- a maneuver currently prohibited. If it's not safe to cross over the double yellow, the lane is substandard, and the vehicle decides to pass anyway, it would have to slow down to 15 mph while passing the bicycle.

Local bicycling advocate Bill Burton, who runs the recycled-bikes advocacy program Library Bike in Arcata and who helped write the bill, says SB 910 removes the ambiguity of what "safe distance" means, as well as relieves drivers of the fear of being fined if they scoot over the double yellow a little to pass a bicycle.

"It's not a revenue-generating bill," Burton said by phone from Sacramento last month, where he was lobbying for the bill's passage. "The idea is to mellow out driving behavior. That three feet of space creates a safer situation."

One time, on Highway 299, Burton had to bail off his bicycle into the gravel shoulder when a cattle truck's trailer was about to nail him. But mostly, he said, he's noticed that truckers and cars usually cross over the double yellow line in narrow situations to give him room. Those double yellows, he noted, were designed for places where cars would not have enough time to pass a large truck. It makes sense to have a different rule for bicycles because they can be passed so much more quickly.

Burton said 18 other states already have similar laws in place. In California, groups have pushed for such a law in the past, to no avail. The current bill has bipartisan support, he said. It sprang from a "bike congress" that Los Angeles Mayor Antonio Villaraigosa convened earlier this year after a taxi cab cut him off in traffic, causing him to fall and break his elbow, according to Jim Brown, communications director for the California Bicycle Coalition. The congress conceived of a "Give-Me-3" campaign and soon posters plastered city buses advising motorists to give cyclists three feet of passing space. The coalition is cosponsoring SB 910 and has expanded its Give-Me-3 campaign statewide.

The bill has some formidable opponents: the Teamsters Union, the Automobile Club of Southern California and the California State Automobile Association. According to a legislative analyst's report, the Teamsters worry that the one-size-fits-all nature of the bill ignores different road conditions and the difficulties some commercial drivers could have meeting the new provisions. The auto clubs, meanwhile, say that requiring a vehicle to slow to 15 mph when passing a cyclist could cause more rear-end collisions "or swerving that could further endanger the bicyclist and other roadway users," writes the analyst.

At least one local trucking company supports the bill. Gary Alto, owner of Alto Brothers Trucking, said by phone recently that, knock on wood, none of his drivers have hit a cyclist from behind nor been cited for crossing the double yellows. Nor have they ever been cited, he said, for crossing the double-yellow to give a bicyclist more room -- although his brother was cited for that in Oregon some years back, he added with disgust.

He likes that SB 910 would make such passing legal.

"I think it's very good for safety aspects," he said. "It allows us to get away from the bike -- as long as it's safe; you can't do it on a turn."

A few years ago, he took part in filming a documentary on truck/bicycle safety, on the frontage road by Clam Beach. "I drove the truck," he said. "And they had the CHP there. ... They had me actually speeding and ... people documenting what the bicyclist did when the truck went by."

It wobbled in the truck's turbulence.

"The more room we've got, the better off we are," Alto said.

An obvious key to the law's effectiveness would be enforcement. If SB 910 passes, the amended provisions would be incorporated into the California Department of Motor Vehicles' driver's handbook. Presumably, cops would start whapping close-shave drivers with fines -- easy enough to prove if they actually knock a poor cyclist over (or if someone sees them drive by too closely). And, presumably, they'll stop cracking down on conscientiously law-breaking motorists -- although they're not really doing that anyway, at least here in Humboldt County.

Officer Paul Dahlen, with the California Highway Patrol office in Arcata, said that his officers don't cite drivers who cross a solid double-yellow to give safe space to a cyclist or other obstacle on the side of the road, as long as the driver isn't endangering someone approaching from the opposite direction.

"We, as law enforcement officers, understand what they're trying to do," he said recently in a phone interview.

Erin Komatsubara, a media spokesperson at CHP headquarters in Sacramento, cautiously confirmed this rule of thumb.

"Everybody has to follow the law," she emphasized, repeatedly. "In extenuating circumstances, officers are allowed to use their discretion."

Dahlen said sideswiping of bikes by passing cars, while common elsewhere in California, is rare in Humboldt. In the past eight months, there were no such collisions.

The state Assembly has between Aug. 15, when it returns from break, and Sept. 8 to look at SB 910. If the Assembly approves, the bill would go to the governor to sign.

Manos, the professor who was sideswiped near the Samoa bridge, looks forward to having what she calls a "three-foot halo" in place around cyclists. But it can't stop there.

"These legal things need to be coupled with the infrastructure," she said. "There really needs to be more marked and designated lanes, more bicycle paths with the freedom of not having to worry about the car being right up next to you."