After a freight train derailed in Richmond earlier this month, questions have emerged about what caused the crash and whether the extreme heat played a role.

Excluding the July train accident in Richmond, Virginia has recorded four derailments, all at speeds under 9 mph, since January, Federal Railroad Administration data shows. The incidents reflect the broader challenge of preventing derailments, which can stem from track defects, equipment failures, human error, or adverse weather conditions.

J.B. Jones Chair of Mechanical Engineering at Virginia Tech and director of the Center for Vehicle Systems & Safety Mehdi Ahmadian is an expert in how extreme weather affects rail tracks, the role of steel in rail infrastructure and how rail operators respond to extreme weather events.

“I can tell you confidently that the railroads do an exceptional job of maintaining the general condition of the track,” Ahmadian said. “There are thousands of trains and rail cars that operate on this complex railroad network that we have around the country, and by and large, they will travel on those tracks safely and without any incidents.”

Ahmadian, also the founder of the Railroad Transportation Laboratory, designed to help improve rail and truck safety through research and to educate students who will enter the transportation industry and advance public safety, said the U.S. rail network is “extremely complex,” carrying mostly heavy freight and sharing passenger trains in some corridors.

With over 35 years in the industry, Ahmadian said he believes railroads do an exceptional job maintaining track conditions. High-profile derailments can distort public perception, he added.

Ahmadian said one misconception is that all derailments result from extreme heat.

Impact to rail tracks in extreme weather

Regardless of the weather, Ahmadian said railroad tracks can be affected by both extreme heat and cold temperatures. This is one of the biggest challenges for railroad operators when moving passengers and cargo.

Even though train wheels look large, Ahmadian said the actual spot where each wheel touches the rail is only about the size of a quarter, roughly one-inch across.

Under extreme heat, Ahmadian said rail tracks can expand and buckle, resembling a large S-shaped curve. Even the slightest deviation in the track can cause a wheel to drop between the rail tracks, triggering derailment, with each railcar carrying thousands of pounds over eight wheels.

In extreme cold conditions, rail tracks can contract as tension increases, like tightening a guitar string, Ahmadian said. If the force exceeds the rail’s strength, it will break, creating a gap in the track and possible derailment.

Steel remains the best ‘practical material’ for rail tracks

Since the 19th century, steel has been the preferred material for railroad tracks and Ahmadian said it’s still the best choice for rail construction and maintenance.

“There is no better practical material that we can use for the extreme demands of running heavy trains,” Ahmadian said.

Steel has evolved over 150 years and is now specifically engineered to withstand extreme mechanical loads from heavy trains and resist wear. 

Rail tracks can last between 20 and 40 years, depending on traffic volume and other conditions, Ahmadian said, which is amazing considering the continuous heavy loads, thermal cycling between heat and cold and constant environmental exposure.

Ahmadian said rail steel is a cost-effective engineering achievement that can’t be easily replaced.

Rail operators’ response to extreme weather

Passenger rail operators regularly adjust travel schedules that can trigger train delays if weather conditions impact rail tracks. Ahmadian says this is common for maintaining safe travel for passengers.

On hot days, Ahmadian said operators may implement “slow orders,” which require trains to run at reduced speeds on affected segments of the rail track and help reduce the risk of a heat-weakened track causing a derailment.

Ahmadian said rail operators could also temporarily suspend traffic if conditions are deemed particularly risky, typically on the hottest parts of the day. He said services typically resume once conditions are considered safe.

Maintenance crews inspect tracks for cracks or breaks caused by cold-induced contraction on extremely cold days.

Crews also investigate rail tracks ahead of trains, often using pickup trucks fitted with rail wheels to move efficiently along the tracks. Ahmadian said these patrols monitor for lateral rail shifting,  signs of track panel shifting or potential buckling. They then recommend slow orders, repairs, or other interventions, if needed.

Richmond derailment still under investigation

CSX is still working on repairing the damage near the intersection of Dock and 20th Streets in Richmond that contributed to three train cars derailing from a 200-car train into the Riverfront Canal on July 3. 

No injuries and no HAZMAT issues resulted from the accident. Crews continue to remove the grain from the three cars submerged in the canal. A spokesperson said the case is still under investigation.