The California Public Utilities Commission (CPUC) closed the world's shortest railway in June after inspectors found the safety mechanism on the wheels had been worn down. But the operator installed new wheels and the funicular reopened July 5.
On Tuesday officials told the L.A. City Council the railway is safe for passengers, but they're still trying to determine why the flanges were so worn.
The movement of the two cars, Olivet and Sinai, through a transition two-thirds up the hill was not behaving as originally designed, said Richard Clark from CPUC.
"It was quite bumpy and rough and the patterns of wear on the track structure and guard rails gave us great concern," Clark said. "We're still trying to determine what the actual root cause of the problem is."
Railway President John H. Welborne disputed the claim that the root cause is unknown.
"The root cause is friction. Wheels wear," said Welborne. "There is always going to be friction when steel rubs on steel. The question is what is the appropriate amount of wear."
The railway rakes riders on one-minute trips up and down Bunker Hill for 25 cents. It reopened last year after a nine-year closure prompted by a 2001 accident that killed someone and injured seven others.
The railway now operates between 6:45 a.m. and 10 p.m.
City News Service contributed to this story.