ALBANY — It could soon be illegal in New York to send text messages while driving — but cops won’t be able to stop you for it.

Despite the fact that a new study shows texting is far more dangerous than other distractions, the bill passed by the State Legislature bars police from stopping someone they see texting while behind the wheel.

The texting prohibition, part of a major set of changes to the state’s teen driving laws, would affect drivers of all ages. But the bill permits only “secondary enforcement” by police, meaning texting while driving would not be enough on its own to qualify as an offense.

Instead, police would have to first ticket for another infraction, such as speeding, before ticketing for texting.

As a result, safety groups say the law has been weakened to the point that many drivers — and police — will simply ignore the ban.

“Secondary laws are much tougher to enforce,” said Anne McCartt, senior vice president of research at the Insurance Institute for Highway Safety, a national industry research group in Arlington, Va. She said a number of studies have found drivers and passengers in states with secondary enforcement of seat belt laws, for instance, don’t buckle up as often as those in states that require “primary” enforcement.

“It’s hard enough to enforce, but make it secondary enforcement and it becomes almost impossible,” said Judith Stone, president of the Advocates for Highway and Auto Safety, a research and advocacy group in Washington, D. C. “It minimizes the deterrent value of the law. It’s like saying, ‘We’re not serious about this.’ ”

Safety groups say secondary enforcement laws are usually done to appease critics in the political process. In the case of the New York bill, which passed both houses with only one “no” vote, the Paterson administration originally proposed a ban on the use of all electronic devices while driving, including iPods.

The Assembly amended it to remove the iPod ban, apply the texting ban only to teen drivers and then put in the secondary enforcement provision over concerns that police would profile young drivers, according to a government source. The final texting bill was expanded to include all drivers, but with the secondary enforcement provision left intact.

Disenchantment with New York’s law — which still awaits Gov. David A. Paterson’s signature— comes as a new federally funded study by the Virginia Tech Transportation Institute shows a crash is 23 times more likely while texting than not.

Tuesday, the AAA Foundation for Traffic Safety also released a new survey finding 80 percent of motorists believe distracted driving is a “very serious threat” to their safety. Overall, 35 percent of drivers feel less safe on the roads than they did five years ago.

Drivers now fear text-messaging drivers — 87 percent — nearly as much as drunken drivers, 90 percent. Still, 18 percent of those same drivers admitted to texting while driving in the past month. And while the vast majority of drivers lamented the dangers of distracted driving, more than two-thirds say they talk on a cell phone while driving.

The Virginia Tech study called for a ban on texting following its findings in a study that placed cameras and other recording devices in the cabs of 200 truckers at seven fleet companies around the country.

The increased danger when texting was far higher than with other distractions, such as entering data into a dispatching device, reading a map or dialing a cell phone.

The study found the potential for a “true crash epidemic” if texting laws are not enacted and enforced.

“It’s all about paying attention to what you’re doing,’’ said Rich Hanowski, director of the Center for Truck and Bus Safety at the Virginia Tech research group. Hanowski, who led the study, said the research’s results involving truckers can easily be transferred to car drivers.

The study examined factors including an “eye glance analysis” that looked at what the eyes of the truck drivers were doing at the time an incident on the road occurred. Hanowski said anything that takes a driver’s eyes off the road for more than two seconds is especially dangerous. When text messaging, drivers on average shifted their eyes from the road to the text screen for nearly five seconds.

Paterson is expected to sign the texting bill, which is part of a larger effort aimed at strengthening teen driving measures, such as requiring more training time behind the wheel and fewer teen passengers in a car driven by a teen. The bill, originally proposed by Paterson’s Department of Motor Vehicles, has not yet been sent by the Assembly to the governor for his consideration.

Proponents used a number of high-profile crashes to convince lawmakers of the need for the ban, including the June 2007 crash that killed five Fairport High School graduates. The driver’s phone had sent a text message shortly before the accident.