WaRa 1 freight car (date unknown). A freight car like this one was involved in the Tsurumi rail accident.
The 43rd wagon of a long freight train (type WaRa 1) hauled by an EF15 locomotive on the down-freight railway derailed and the two following wagons overturned, blocking the adjacent "up" passenger railway. Within seconds, a 12-carriage EMU train traveling to Tokyo collided with the freight wagons and the front three carriages (KuHa 76039, MoHa 70079 and KuMoHa 50006 respectively) derailed, falling into the side of the fourth and fifth carriages of another 12 carriage train passing on the down-line to Kurihama. The multiple collision left 161 dead and 120 injured.
The initial JNR investigation found that the speed of the freight train (60 km/h) was not excessive, nor were any problems found with the line or rolling stock. For five years from 1967 until 1972, the RTRI carried out tests on a test track located at Karikachi Pass in Hokkaidō on an abandoned section of the Nemuro Main Line (Shintoku - Niinai) using the same rails and rolling stock and found that the combination of wheelset design, rail cross section and wear, and track geometry all had a role in the derailment. As a result of the investigation, the old method of static track inspection was replaced with new track inspection cars employing dynamic inspection methods and data collection.