LOS ANGELES — On a bad night at the ports, trucker Alex Gutierrez will endure a collision so jarring that, if it happened on the streets, he'd be exchanging insurance information on the side of the road.

On a good shift, he'll have several such collisions.

It's all in a night's work at the Los Angeles and Long Beach ports.

Several months into a radical revamping at the ports that is keeping cargo terminal gates open almost around the clock, Gutierrez will coax his truck through an average of one haul every two hours, slamming the aging cab into a cargo container and chassis to hook them together. That pace is a tremendous improvement over last year, when a backup of more than 90 ships and an acute shortage of dockworkers forced drivers to wait for hours.

But even a perfect shift won't compensate Gutierrez for another night away from his family, the 40-year-old driver said. He's making plans to quit.

"There's just no way I'm going to be driving this truck at 45," Gutierrez said.

At a time when record imports are pouring in from Asia, the truckers who work the largest U.S. seaport complex say they are struggling because of the strain of longer work hours and the pain of high diesel prices. With truckers in short supply nationwide, a steady loss of experienced drivers could threaten the ports' recent return to smooth operations, some warn.

OffPeak, the program to push port traffic away from peak daylight hours to reduce congestion, wasn't designed to make port work more lucrative for drivers, who don't receive extra pay for night hours. Officials had hoped that it would shorten the lines into the port, providing more loads per shift.

Short-haul port drivers like Gutierrez occupy the bottom rungs of the trucking industry, lacking the higher incomes and union clout of long-haul drivers. Usually independent owner-operators, they can afford only the oldest, least fuel-efficient and most polluting trucks.

The average port trucker will earn $50 for moving a loaded container to or from the port and $35 for an empty one. A typical haul will include both a pickup and a drop-off, so, on a good night, a driver can collect $340 in gross income.

But most nights aren't trouble free, and drivers say that they can face delays when a paperwork snafu interrupts a haul. And there are other hardships.

Alfonso Gonzalez, 51, said that he preferred his old hours because he finds it difficult to sleep during the day, and he suffers from an eye condition that makes approaching headlights look as if they are surrounded by a bright halo. Now, Gonzalez said, less work is available during the day, and he has to work nights, too.

"If I can't find enough work during the day, I will wind up working 12 or 16 hours because I have to keep working into the night," Gonzalez said. "Sometimes you have to work that long to get the $300 or $400" needed to make a profit on a given night.

Gutierrez would rather be at his Compton home at night where he can hold his 2-year-old daughter, Rachel Alexa, and help his wife Berta make sure their sons, Rigo and Alfredo, are studying and not watching television. On weekends, he would rather go to the boys' baseball games or watch football. And he'd love to forget the feeling of pumping $200 worth of diesel and knowing it won't fill the tank.

"My wife and I talked it over. She's going to school and will be a teacher, and I'm going to go into real estate," Gutierrez said as he stapled the night's paperwork together at the Maersk Sealand Pier 400 terminal.

Gutierrez's battered dark green 1989 Cummins Big Cam Freightliner is long past its prime, requiring hours of weekly maintenance to keep it roadworthy. His first load of the night — a 50,000-pound container of compressed hay cubes bound for Yokohama, Japan — is ready for him at the Los Angeles Harbor Grain Terminal.

Gutierrez's truck has more than 500,000 miles on it, of which 200,000 are his miles. He spends upward of $1,200 a month on fuel for a truck that gets 5 to 7 miles per gallon. Until recently, maintenance and repairs accounted for $250 a month with insurance amounting to $7,000 a year. Throw in highway taxes and permits and Gutierrez was clearing $30,000 or so a year.

On this night, when Gutierrez arrives at the APL terminal with his hay cubes, the pace is slow. He waits at the gate as the phone there rings 20 times before a clerk picks up and allows him to enter.

Inside, Gutierrez is given a place to drop off the container, but there are no empty spaces in the assigned row. Other drivers, perhaps in a hurry to move on to another job, have left the wheeled chassis that carry the containers in the wrong space. Gutierrez not only must find another space, but he also has to stop and report where he left the container or risk a $100 fine.

No one knows exactly how many drivers have stopped working the ports. Several of Gutierrez's friends have quit, taking jobs in construction or at supermarkets. None of them, he said, misses the ports.