The Hawaii Fire Fighters Association today endorsed Kirk Caldwell for Honolulu mayor, citing what the union called his proven track record and support for the city’s $5.27 billion rail transit project.

Union president Robert Lee said the organization’s executive board reached the decision after reviewing its 2010 endorsement, which also went to Caldwell.

“It was very clear, with the choices that we had, who we were going to endorse,” Lee said. “it wasn’t really much of a competition for us.”

Caldwell is running against Mayor Peter Carlisle and Ben Cayetano, a former two-term governor who is the only one of the three candidates opposed to the rail project.

Lee said the union supports rail because of its potential to reduce traffic congestion.

“If you look at the traffic that goes on on that side of the island — rush hour traffic — it’s very easy to say that by not doing anything to address the traffic, people are dying,” Lee said. “We can’t get there fast enough.

“If we can’t get there fast enough — as everyone is aware, minutes make a difference whether you live or die — it’s very clear that if we don’t do something about the traffic, people will continue to die.”

The HFFA represents about 2,900 members statewide.

Caldwell also has been endorsed by the State of Hawaii Organization of Police Officers.