Problems are still plaguing the Long Island Rail Road's effort to install a system that can slow or stop a train in an emergency.

Positive train control, or PTC, is a federally mandated electronic crash prevention system that is set to be installed on all LIRR trains. It automatically slows down or stops a train that goes too fast or violates a signal.

During a committee meeting Monday, a Metropolitan Transportation Authority contractor said a mistake was discovered in how PTC was being installed on train cars, which is now delaying the project even more.

After several delays, the LIRR was given another extension, this time to 2020, to finish implementing PTC. The agency could be fined up to $27,000 a day if it doesn't.

MORE: Defective equipment delays PTC installation on LIRR

State Sen. Jim Gaughran says PTC needs to be finished by the deadline or sooner and that hundreds of thousands of LIRR riders count on the MTA to ensure their safety.

News 12 spoke with some commuters who say they weren't surprised by the delay, with one person saying "there's always issues."

MTA officials say they still expect to meet the 2020 deadline.