​On March 10, 2022, about 10:31 a.m. local time, southbound Caltrain Train 506 struck three hi-rail construction vehicles at milepost 11.6 on Main Track 2 in San Bruno, California. The train’s locomotive derailed, and all three construction vehicles were destroyed. Released fuel from the construction vehicles fed a fire that spread to one of the passenger railcars. Eight people were transported to local hospitals. One railroad construction employee sustained serious injuries. One train crewmember was treated and released at a local hospital. Six passengers were treated for minor injuries and subsequently released. Visibility in the area at the time of the collision was clear; the temperature was 60°F with no precipitation. Caltrain estimated that the property damage exceeded $1.4 million. 

​We determined that the probable cause of this accident is the roadway worker-in-charge releasing exclusive track occupancy protection leaving workers and construction equipment unprotected on the main track due to his degraded performance from excessive workload.