As it turns out, LIRR is spelled L-A-T-E

You’re guaranteed to be late at least once a week if you travel on the Long Island Rail Road’s Montauk line, if its 89.4 percent on-time performance rating doesn’t improve.

According to the Long Island Rail Road 2010 operating report released yesterday, the LIRR had its worst on-time performance rating in five years — with 92.8 percent of trains pulling into stations on time.

“It’s not a surprise,” said Ira Greenburg, the head of the LIRR commuter’s council on the MTA Board. “The MTA and the Legislature have to focus on improvements so that people can get to work on time. Sure, they say it was snow, a fire — but if it wasn’t that, it would be another issue.”

The LIRR fell short of its 95.1 percent on-time performance goal. In 2010, trains broke down less frequently even though they were often late in arriving at stations. (The LIRR considers a train on time if it comes in within five minutes and 59 seconds of its scheduled arrival time.)

“We are not happy with the performance,” LIRR spokesman Salvatore Arena told Metro. “A fire at the Jamaica station and unusual weather events played a major role.”

“There’s always a 10-minute delay for one reason or another,” said LIRR commuter Barbara Horn, a professor at Nassau Community College. “The fares are very costly and makes people think of other modes of transportation.”