On September 8, 2022, about 2:40 a.m. local time, a conductor and engineer of Union Pacific Railroad (UP) train ISILB5-07 were killed when the train collided with railcars stored in a siding in Imperial County, California.[1] Train ISILB5-07 had been traveling timetable eastbound on main track 2 of the Yuma Subdivision when, because of a change of route plans, the train reversed direction into Bertram siding, a signal-controlled siding at milepost 646.1.[2] Upon entering the siding, with helper locomotives in the lead, the train traveled about 802 feet before colliding with a string of 74 empty intermodal railcars that had been stored in the siding since December 2021.[3] The two lead locomotives and one intermodal railcar of train ISILB5-07 derailed, along with two of the empty stored intermodal railcars. (See figure 1.) Visibility conditions at the time of the accident were dark and clear with a haze near the ground, there was no precipitation, and the temperature was 86°F. UP estimated damage to track and equipment to be about $1.2 million.
[1] (a) All times in this report are local time unless otherwise noted. (b) Visit
ntsb.gov to find additional information in the
public docket for this National Transportation Safety Board (NTSB) accident investigation (case number RRD22LR014). Use the
CAROL Query to search safety recommendations and investigations.
[2] (a) A timetable is a publication containing information on the movement of trains or equipment. Timetable directions are based on the rail network, so they can differ from compass directions. (b) Signal-controlled siding refers to the remote control of railway signals and block systems that control train movements onto other tracks.
[3] (a) Helper locomotives are attached to trains and provide additional horsepower to assist on grades. (b) At the time of the accident, train ISILB5-07 was traveling 28 mph. The maximum authorized speed for trains diverting into Bertram siding is 30 mph.
We determined that the probable cause of the Imperial County, California, collision was the routing of Union Pacific Railroad train ISILB5-07 into Bertram siding, which was occupied by 74 empty intermodal railcars, made possible by the inappropriate removal of a computer-aided dispatching system block on the siding at the dispatch center.
Contributing to the cause of the accident were:
- the Bertram siding track not being spiked or clamped, as Union Pacific Railroad rules require for tracks where railcars are being stored long-term, and
- the surface rust on the rails and wheels of the stored railcars that degraded the performance of the track circuit in Bertram siding and caused the computer-aided dispatching system to inaccurately indicate the siding was unoccupied.
