Hours after a 28-car Norfolk Southern train derailed Saturday in Springfield, Ohio — the third incident for the freight railroad in just over a month, including the toxic disaster in East Palestine, Ohio — internal emails show railroad officials making broad safety adjustments for rail cars.

An internal Norfolk Southern email sent Sunday and obtained by CNBC with a time stamp approximately 11 hours after the latest derailment indicated that Norfolk Southern was planning to reduce train length in an effort to prevent future incidents. Sources tell CNBC the email was given to Norfolk Southern yard managers, who are union workers in charge of stacking the trains.

A Norfolk Southern spokesman told CNBC that guidance has since been updated and the train carrier is now mandating that any trains over 10,000 feet use distributed power, meaning the trains would be powered from several locations across the length of the train, not just from the front. Distributed locomotives are wirelessly controlled from the leading locomotive in both power and braking as needed to assist in the management of in-train forces.

Norfolk Southern told CNBC other railroad carriers currently have this safety practice in place.

“At Norfolk Southern, the safety of our crews and the communities we serve comes first,” Connor Spielmaker, spokesman for Norfolk Southern, wrote via email. “Part of enhancing safety is continuously evaluating how we operate our network, and we have been examining immediate ways to move that goal forward. Today, as an interim step, we are ensuring all trains longer than 10,000 feet are operated with distributive power. We will build on this interim change to drive final policies that are appropriate for each segment of our railroad.”

Norfolk Southern told CNBC it is actively reviewing all safety protocols to make sure trains are operating appropriately across the network.

Still, Jeremy Ferguson, president of SMART-Transportation Division, the country’s largest rail union, said his workers are being told the railroad will limit train length.

“I have seen Norfolk Southern documents to yardmasters [Monday] morning from the field that is telling us trains no longer than 10,000 feet regardless of distributed power,” said Ferguson. “The train that derailed on Saturday already had distributed power, so their comment to CNBC does not make sense. I will say it is a good move by Norfolk Southern to take the right steps in reducing the train lengths, because the trains are too long.”

Train lengths have been a contentious issue for railroads and labor unions in negotiations. Railroads currently run on what’s called precision scheduled railroading, or PSR, which has led to much longer trains — as long as three miles.

Trains are stacked based on the destination, not weight distribution, with stacking of the first destination at the head of the train and in sequence until the last drop-off.

Railroads have redesigned train length in an effort to use fewer people and to move more cars with fewer locomotives, reducing costs and generating higher profits. But railroad unions and customers have raised safety and service concerns.

The derailment in Springfield marks the third derailment since the Feb. 3 East Palestine train disaster, in which hazardous materials spilled.

On Feb. 16, a 135-car Norfolk Southern train traveling from Detroit to Peru, Indiana, derailed approximately 14 miles outside the yard in Romulus, Michigan. According to the investigative report for that incident, the tonnage profile shows heavy cars at the head of the train, in the middle and in the rear, with empty cars scattered throughout.

The derailment is still under investigation, but according to one on-site investigation report, human error is likely to be a large factor: An “engineer panicked and applied heavy dynamic braking which resulted in an emergency brake application and derailment.”

The National Transportation Safety Board announced it is sending investigators to the Springfield site.