Tsamouris, the Fastener Specialists©
Four missing high-strength Grade 8 bolts are at the center of the MTA’s investigation into the January 10,
2024, derailment of an F train in Coney Island, Brooklyn. The bolts, which were meant to secure a critical
component called the “radius arm” to the train’s undercarriage, were discovered missing from the derailed
car.
Radius arms play a crucial role in keeping a subway car’s wheels and axles properly aligned during
movement. Experts warn that a fallen or broken radius arm can lead to a derailment.
While the cause of the derailment is still under investigation, with track issues and other factors not yet ruled
out, the MTA believes the missing bolts may have contributed to the incident. It remains unclear whether the
bolts broke before disappearing or were improperly installed.
In response to the derailment, the MTA has inspected approximately 50,000 radius arm bolts across its
subway fleet, focusing on R160 cars and similar designs. No systemic issues were found during these
inspections, and officials believe riders are not currently at risk.
At Tsamouris, we recognize the critical role that high-quality fasteners play in ensuring the safety and
reliability of transportation systems.