CSX Replaces One of Nation's Most Complex Rail Crossings

November 18, 2025 – CSX recently completed a complex replacement of the Darby Diamond in Pennsylvania, an intersection where freight rail, a four-lane highway, and two mass transit lines all meet at the same level.
 
This crossing is one of the most challenging to maintain in the country due to its unique combination of traffic and different track gauges between CSX and SEPTA, the local transit authority. The Darby Diamond is the only location where a Class I railroad crosses a four-lane roadway and two mass transit tracks — at-grade in a single intersection. To add to the difficulty, SEPTA’s track is Pennsylvania gauge and CSX uses standard gauge, creating a flange-bearing crossing for the trolleys.  
 
The replacement, which began on October 29, involved removing old crossing materials and installing a new diamond with concrete panels. The project required precise, round-the-clock coordination between CSX, SEPTA, the Borough of Darby, and the State of Pennsylvania. Traffic detours were put in place to minimize disruption to commuters during the construction.
 
"The success of the project relied on conducting thorough daily job briefings, making sure we had the right equipment and materials ready, and having trust in our craft employees,” said Peter Cooper, Senior Track Supervisor at CSX.
 
Due to its complexity and heavy use, the Darby Diamond is typically replaced every five to seven years. The successful and on-schedule completion of this project showcases the CSX Engineering team's meticulous planning and collaborative execution and underscores CSX’s commitment to safe and reliable operations.