Metro officials anticipate additional sections of the light-rail track could break, adding to the multiple gaps they’ve already identified in the system. And the veteran of another light-rail system said even more sections will come apart, no matter how much care contractors take while laying the steel tracks.

“You’re going to get breaks,” said Ron Benson, deputy general manager of the TRAX rail system in Salt Lake City.

But officials with Metro and other systems where tracks have split apart said the much-publicized — yet not fully understood — gaps on the Arizona system shouldn’t jeopardize passenger safety.

The breaks raised speculation about faulty construction or design on the 20-mile, $1.4 billion system.

But officials at other agencies agree such cracks are common the first winter after rail is put down, as cold temperatures cause metal to contract and split. Problematic areas become obvious the first year and are less frequent in following years, Benson said.

He characterized breaks as nuisances, not serious threats.

The 19.7-mile long TRAX had four breaks on new lines before the system was ready for passengers. At least two breaks followed once trains carried commuters, including one recently on a track in service seven years, Benson said.

As on the Metro line, most gaps are two inches. The breaks aren’t ideal but are passable.

“You could run over a three-inch break. You wouldn’t hardly even know it,” Benson said. “You’re not coming off the track.” At most, passengers would feel a bump, he said.

Metro wouldn’t knowingly ride over a gap, said Joe Marie, director of operations and maintenance. Once service begins in December, the first train of every day will run without passengers at 3-5 mph as a conductor inspects the route for breaks or other problems.

Metro will conduct even more inspections by foot, Marie said.

“Every foot of the 20 miles will be inspected on a weekly basis,” he said.

If a break is found, Metro would shift the train to a parallel track until crews fixed the gap.

Marie acknowledged a rail could break midday but said that wouldn’t pose a risk in most cases. A gap of 5 or 6 inches would be passable, he said. But it’s likely a train could go over Metro’s largest gap, 7 inches, while causing a bump and making lots of noise.

“We’re not talking about a derailment situation,” Marie said. “We’re talking about something that doesn’t sound right.” The trains won’t go over 35 mph in most cases, so they’re not likely to jump the tracks.

TRAX operators identified breaks before a train ever could pass over them, Benson said.

When they’ve been found, workers have welded metal pieces in the gap and had the track back in service within three hours of discovering the problem. Each repair cost about $2,000.

Five breaks occurred on the Hiawatha line in Minneapolis before its trains carried their first passengers. New metal was welded into the gaps and no other tracks have broken since the gaps were discovered in late 2003 and early 2004, said Bob Gibbons, Hiawatha’s director of customer services.

The breaks in the Phoenix line sound common for a new system, Gibbons said.

“I don’t think it means you have shoddy rail or shoddy welding,” Gibbons said.

Even heavy-rail tracks break in cold, Benson said. Union Pacific tracks adjacent to TRAX lines broke in many places recently when Minneapolis temperatures plunged to 6 degrees, he said.

“The Union Pacific has been repairing breaks like mad,” Benson said, adding the railroad constantly deals with breaks.

Metro officials announced 11 breaks earlier this week but later described the number as an oversimplification. Eight breaks have occurred, Metro spokeswoman Marty McNeil said later.

Nine other spots are chipped or fractured and are a concern.

“We think there’s a chance they’re going to break,” McNeil said.

Metro has hired New Jersey-based Zeta-Tech Associates to identify the cause and possible fixes. Transit officials refused to speculate on repair cost or if warranties cover the fixes until the consultant releases a report in a few weeks.

The initial breaks on the Salt Lake line didn’t cost taxpayers anything, Benson said. Such repairs were warranty items and covered for one year after passenger service began, which Benson said is a common contract clause authorities negotiate with contractors.

The Metro repairs would likely come from a contingency fund of $43 million if they aren’t covered under warranty.