LOS ANGELES (AP) — Los Angeles County transit authorities are struggling to fix a flaw in a commuter train track that increases the risk of derailments.

The Los Angeles Times (http://lat.ms/N7rZsR) says Metropolitan Transportation Authority workerswelded extra metal on a junction of the Expo light-rail line south of downtown. But the weld — designed to fix an track alignment problem — has been redone several times because of frequent wear.

State regulators on Wednesday said the weld has broken twice since May. It will be re-welded Friday night. The repair will thicken a key part of the junction between the recently opened Expo line and the busy Blue Line that makes a sharp turn.

Officials say the problems have not endangered passengers or affected trains.

Copyright 2012 The Associated Press.