Flashing blue and red lights in your rearview mirror can snap you out of that engrossing telephone conversation pretty quickly.
So, too, can the impact from the pedestrian you just hit in the crosswalk.
To prevent injuries or fatal accidents, police around the region are out in full force, looking for people violating cell phone laws. Through enforcement and education, they hope to drive down the number of wrecks caused by distracted driving, which is the primary cause of 28 percent of all wrecks nationwide.
Ralph Whittle, 58, became the victim of a distracted driver last month when a car hit him as he walked in a crosswalk at College and Stoddard avenues in Modesto.
He was on his way to a music class at Modesto Junior College when he was swept off his feet by the grill of a Volkswagen, driven by a young woman, a fellow MJC student, who was chatting with a friend about where to meet.
Whittle remembers his feet in the air as he was flipped onto the Volkswagen's windshield before he fell to the ground on his hip. He suffered major bruising and still experiences neck and shoulder pain, but considers himself fortunate that he wasn't more seriously injured.
During the past week, Stanislaus County law enforcement agencies have targeted distracted drivers, resulting in dozens of tickets to people texting while driving or using their cell phones without a hands-free kit.
The so-called maximum enforcement effort is one of three scheduled in the next six months in the greater Sacramento region to target distracted drivers. A grant sponsored by the U.S. Department of Transportation's National Highway Traffic Safety Administration will pay for officer overtime associated with the crackdown.
Teenagers and young adults sometimes seem able to communicate only via their cell phones, but people of all ages, races and socioeconomic groups can be cell phone obsessed.
Most people tell officers they were making a quick phone call or answering a call just to tell the person on the other end that they were driving.
" 'Real quick' means you look down and someone pulls out in front of you and you are in a bad situation," said California Highway Patrol officer Chuck Leon.
Wednesday, Leon stopped a man who said he was taking a quick "business call." After getting a ticket, the man said he would invest in a hands-free device for his phone.
Another man pulled over by Leon at Pelandale Avenue and Salida Boulevard said he has a hands-free device "but my car's a mess and I couldn't find it."
The phone call he answered came from his wife, telling him where to pick up their children. Ticket in hand, the 27-year-old's advice to other drivers was to "turn off your phone while you're driving."
Don't distract others
That's one of the habits traffic officers are trying to instill in drivers: Turn off the phone, put it out of reach and record an outgoing message telling callers you don't answer your phone while driving.
They also want people to refrain from calling or texting others they know are driving.
All of the people Leon cited Wednesday were so distracted they didn't notice when his marked patrol car pulled up alongside their vehicles and he looked directly at them.
A woman Leon caught texting at a red light on Dale Road was surprised she couldn't use her phone while she was stopped in traffic.
Leon pointed out: "Even when the light turned green, you didn't go because you were too distracted with your phone."
The state Vehicle Code states that a driver cannot "write, send, or read a text-based communication."
Some might argue that applies only to texting, Facebooking, tweeting, e-mailing or some other type of communication with another person.
But Modesto police officer Ben Croutil said you need only to be reading or writing data on your phone for the law to apply. That means typing an address into your GPS, matching songs on the radio with the Shazam application or using any other kind of application on your phone, he said.
Officers can, and are, using other vehicle codes to address distracted driving of all types. A driver can get a ticket for unsafe speed for watching a video on the monitor in his car because that kind of activity isn't safe at any speed, Croutil said. Similarly, there is no law against applying makeup while driving, but as soon as it causes a person to veer over a lane line, the driver is getting a ticket.
Recipe for disaster
People who hold their cell phones near their lap to text might be making it harder for officers to detect what they're doing, but Leon said the hand left on the steering wheel will naturally move in the direction of the eyes, so it'll drop, steering the car into the lane next to you.
You can try to conceal it or try to argue your way out of a ticket, but all your efforts will have been in vain if you injure or kill someone else because you were too distracted to prevent an accident.
Cell phone usage was determined to be a contributing factor in a wreck that killed a 4-year-old boy last year in Stanislaus County, according to California Highway Patrol officer Eric Parsons.
Melissa Moody, 29, crashed into the back of the car in front of her, which caused her car to spin into oncoming traffic at Bradbury and South Walnut roads in Turlock, where she was broadsided by another car.
Moody's 4-year-old son was killed in the wreck and her 2-year-old daughter suffered major injuries. She pleaded no contest to misdemeanor vehicular manslaughter earlier this year.
Her attorney, Kirk McAllister, said "following too closely" was the primary factor in the wreck, but Parsons said cell phone usage was an associated factor. Officers found the Facebook application on her phone open, he said.
The woman who hit Whittle, the MJC student, got a point on her driver's license and is on the hook for his medical bills, which exceed $10,000.
"Be aware and be considerate," Whittle said. "It's the holiday season and everyone wants to be with their families, so do your part."
Bee staff writer Erin Tracy can be reached at firstname.lastname@example.org or (209) 578-2366. Follow her on Twitter, @ModestoBeeCrime.
BEHIND THE WHEEL
Things you should know when you get in the driver's seat with your cell phone:
Just because your phone isn't up to your ear doesn't mean you are getting out of a ticket. People who think they can hold their phone out in front of them while it's on speaker are wrong. You can keep it in your center console on speaker phone, but that's about it.
The law allows you to use your phone to dial a number while driving, but then you need to put it down. Still, law enforcement urges drivers to pull over to dial a number.
You can use your phone without a hands-free kit for emergency purposes such as calls to law enforcement, a fire department or a health care provider. But remember, law enforcement can verify whether you called 911, so don't lie.
Just because you are stopped at a red light or in a traffic jam doesn't mean you can talk or text on your cell phone. The distraction can cause you to hold up traffic or prevent you from taking necessary evasive action.
If you are using ear buds as your hands-free device, you may have only one in while you are driving.
Cell phones aren't the only thing that can distract you. Applying makeup, turning around in your seat to yell at the kids, even changing the radio station can be distracting enough to cause a wreck. "You are in a 6,000-pound vehicle traveling 35 miles per hour at 50 feet per second," said Modesto police traffic Sgt. Craig Breckenridge. "You take your eyes off the road for just two seconds and you have a 6,000-pound bomb waiting to go off."