Inadequate safety monitoring may have played a role in last week’s fatal accident in which four workers died while clearing weeds from railway tracks at a train station in Tochigi Prefecture, investigative sources have said.

The accident occurred at Shin-Kanuma Station on Tobu Railway’s Nikko Line in the city of Kanuma at around 10:45 a.m. on Aug. 20.

The four victims were from Tobu Construction — a Tobu Railway affiliate based in the city of Nikko in Tochigi Prefecture — and a subcontractor. They were hit by a Spacia X limited express train.