The Long Island Rail Road says testing on its fire-damaged switching system will last through the weekend as passengers faced a fourth day of schedule changes and delays.
LIRR says about 68 percent of its usual evening rush hour trains were in operation Thursday on the nation's largest commuter railroad.
And officials said that the process of testing and replacing wires and switches has actually uncovered new problems.
"Some additional damage is yet being discovered -- requiring further equipment replacement," the LIRR said in a statement. "It is likely that the testing and additional replacements will take several days to complete."
On Friday, the railroad says it plans to run its popular afternoon express to Montauk, known as the Cannonball, as well as its usual weekend Hamptons Reserve Service.
The LIRR is repairing a complex network of wires and switches following a cable fire on Monday.
The commuter rail system carries about 265,000 daily riders.
For more information on service changes, check the LIRR's website.