Saturday marks five years since the fatal Metro-North derailment in the Bronx that killed four people.

Three of the victims in that derailment were from the Hudson Valley.

An investigation revealed that the engineer fell asleep at the control. The train was speeding when it approached a sharp curve near the Spuyten Duyvil station and jumped the tracks.

The derailment prompted calls for the installation of an automatic braking system known as Positive Train Control (PTC), which former employees of the MTA say would have prevented the crash.

"The train would've been arrested mechanically," says Kent W. Patterson, a retired project manager for the MTA. "The speed would've been reduced and stopped in a safe manner."

Despite a congressional mandate in 2008, the MTA failed to have PTC installed.

After the derailment, the MTA was given until Dec. 31 of this year to install PTC on all of its railways.

Commuters who take Metro-North say they would feel safer if it was installed.

"There has to be somebody who is in control of the train and if that's a machine, then it's a machine," says Stephanie Coggins, who rides Metro-North twice a day.

The MTA, however, is expected to miss its Dec. 31 deadline and is asking for a two-year extension.

Last month, Metro-North successfully tested PTC on the Hudson line.