Collision of a Caltrain passenger train with Hi-rail maintenance vehicles on March 10, 2022 in San Bruno

The train and maintenance vehicles after the collision. (Photograph courtesy of San Bruno Fire Department.)

This is preliminary information, subject to change and may contain errors. Any error in this

report will be corrected when the final report is completed.

On March 10, 2022, at approximately 10:33 a.m. local time, southbound Caltrain 506 struck three stationary track (or hi-rail) maintenance vehicles at mile post (MP) 11.6 on the main track 2 near San Bruno, California. 1 The locomotive derailed and the three maintenance vehicles were destroyed. Fuel from the road-rail maintenance vehicles leaked and fueled a fire that spread to one of the passenger cars. (See figure.) Fourteen people reported injuries: 12 passengers, 1 train crew member and 1 maintenance contractor. Of those, seven were transported to local hospitals and seven were treated and released at the scene. The weather at the time of the collision was clear skies, a 17 mph north wind and a temperature of 60°F. Visibility was at least 7

miles. Caltrain and its contractors estimated the property damage at nearly $1.4 million.

Train 506 consisted of a single lead locomotive and five passenger cars. The three hi-rail vehicles were two flatbed trucks with telescopic boom cranes and a full-size, heavy-duty pick-up truck.

Prior to the collision, the road worker was given exclusive permission to occupy the train dispatcher’s track, and track units entered main track 2 at approximately 9:50 a.m.[2] They proceeded to MP 11.6 and stopped to load construction materials and catenary poles placed in a fenced area next to main track 2.[3]At around 9:58 a.m., the road attendant contacted the train dispatcher and freed up exclusive occupancy of the track.

According to locomotive event recorder data, train 506 was traveling south on Main Track 2 at 63 mph toward Millbrae Station, after making a scheduled stop at 22nd Street Station. Main Lane 2 has a maximum permitted speed of 79 mph. As train MP 11.6 approached, the engineer saw the three vehicles on the track and applied the train’s emergency brake. The train slowed down but did not stop before hitting the vehicles. The train crew immediately began evacuating passengers through the cars to the rear of the train.

Following the collision, employees of the nearby San Bruno Water Corporation construction site used their work equipment to access the scene. First responders included personnel from the City of San Bruno; Central County, including Burlingame, Hillsborough and Millbrae; San Mateo County; the city of South San Francisco; and the Menlo Park Fire Protection District. Passengers and crew were fully evacuated and fire suppression was complete by 11:14 a.m.

At the scene, National Transportation Safety Board investigators examined the crash site, equipment, signal system and lane; conducted interviews; tested the train’s braking system; and collected employee and system records. The National Transportation Safety Board investigation is ongoing. Future investigative activities will focus on safety, training and monitoring of railway workers, and regulatory compliance.

Parties to the investigation include the Federal Railroad Administration; Caltrain; the California Public Utilities Commission; the Brotherhood of Locomotive Engineers and Trainmen, International Association of Sheet Metal, Air, Railway and Transportation Workers – Transportation Division; the Brotherhood of Railway Signalmen; the Brotherhood of Way Maintenance Employees; TransitAmerica Services, Inc. and Balfour Beatty.[4]


[1] (a) All times given in this preliminary report are in local time, unless otherwise stated. (b) A road-rail vehicle is a highway maintenance machine manufactured to meet Federal Motor Vehicle Safety Standards and equipped with retractable flanged wheels for travel on railroad tracks in addition to the highway.

[2] (has a road worker is a qualified employee to establish wayside protection of pavement working groups against collisions with trains. (b) Under exclusive lane occupancy, a train dispatcher denies trains permission to run at certain locations; in this case, the working limits.

​[3] Catenary poles support on the overhead electrical system used to supply power to electrified railway equipment.

​[4] The Brotherhood of the Ways Employees Division spells the word “Employees” in its name with a final e.

Jose P. Rogers