PALO ALTO, Calif. — Driving around a college campus can be treacherous. Bikes and scooters zip out of nowhere, distracted students wander into traffic, and stopped cars and speed bumps suddenly appear. It takes a vigilant driver to avoid catastrophe.

Jesse Levinson doesn’t worry much about this when he drives his prototype Volkswagen vehicle around the Stanford University campus. A computer vision system he helped design keeps an unblinking eye out for pedestrians and cyclists, and automatically slows and stops the car when they[0x12] enter his path.

An array of optical and radar sensors monitor the surroundings of a growing number of cars traveling the nation’s highways and, in some cases, even track the driver’s physical state. Pedestrian detection systems, like the one that Levinson, a research scientist at Stanford’s Center for Automotive Research, has helped design, are already available in luxury cars and are being built into some midrange models.

The systems offer auditory, visual and mechanical warnings if a collision is imminent — and increasingly, if needed, take evasive actions automatically. By the middle of this decade, under certain conditions, they will take over the task of driving at both high and low speeds.

LEGAL AND INSURANCE ISSUES ARISE

But the new systems are poised to refashion the nature of driving fundamentally long before autonomous vehicles arrive.

“This is really a bridge,” said Ragunathan Rajkumar, a computer science professor who is leading a Carnegie Mellon University automated driving research project partly financed by General Motors. “The driver is still in control. But if the driver is not doing the right thing, the technology takes over.”

Although drivers — at least for now — remain responsible for their vehicles, various legal and insurance issues have already arisen, and researchers are opening a line of study about how humans interact with the automatic systems.

What the changes will mean to the century-old U.S. romance with the car remains to be seen. But the safety systems, the result of rapid advances in computer algorithms and the drastically falling cost of sensors, are a practical reaction to the modern reality of drivers who would rather talk on the phone and send text messages than concentrate on the road.

Four manufacturers — Volvo, BMW, Audi and Mercedes — have announced that as soon as this year they will offer models that will come with sensors and software to allow the car to drive itself in heavy traffic at speeds of up to 37 mph. The systems, known as Traffic Jam Assist, will follow the car ahead and automatically slow down and speed up as needed, handling both braking and steering.

At faster speeds, Cadillac’s Super Cruise system is intended to automate freeway driving by keeping the car within a lane and adjusting speed to other traffic. The company has not said when it will add the system to its cars.

CURRENT LIFE SAVERS

Already, actions like steering, braking and accelerating are increasingly handled by software rather than the driver.

“People don’t realize that when you step on anti-lock brakes it’s simply a suggestion for the car to stop,” said Clifford Nass, a director at the Center for Automotive Research at Stanford.

How and when the car stops is left to the system.

The automobile industry has been motivated to innovate by growing evidence that existing technologies like anti-locking braking systems and electronic stability control have saved tens of thousands of lives.

In November, the National Highway Traffic Safety Administration recommended that all new cars be equipped with collision avoidance technologies, including adaptive cruise control and automatic braking. Two states— California and Nevada — have passed laws making it legal to operate self-driving cars as long as a human being is inside, able to take over.

The agency recently reported that one system, electronic stability control, or ESC, which digitally detects the loss of traction and compensates automatically, saved 2,202 lives from 2008 to 2010. Federal safety regulations began phasing in electronic stability control on small trucks and passenger vehicles in 2007.

SILICON VALLEY LABS

Innovation and deployment of the crash-resistance technologies accelerated after 2010, with news that Google had a secret program to design self-driving cars. Google has not said whether it intends to sell its vehicles.

Ten automakers have advanced research laborator-ies based in Silicon Valley. The most recent one was established by Ford Motors in Mountain View, Calif., in June.