3:25 P.M. UPDATE: The South Shore Line is report that, as of 3:20 p.m., Positive Train Control communications have been restored, and all stopped trains "will be resuming service shortly."

The PTC issue caused the following delays:

• EB Tr 11: 20-30 minutes
• WB Tr 224: 20-30 minutes

ORIGINAL: SOUTH BEND, Ind. -- The South Shore Line announced at 2:55 p.m. Tuesday, all train traffic has stopped due to Positive Train Control issues.

The amount of the delay is unknown at this time.

According to the Federal Railroad Administration, the Positive Train Control (PTC) system is designed to prevent train-to-train collisions, over-speed derailments, incursions into established work zones, and movements of trains through switches left in the wrong position.