The problem derives from the fact that some of the old carriages on Swiss trains use toilets that deposit faeces directly onto the tracks. The human waste usually stays in place until it dries or the rain washes it away.

But an exception occurs whenever someone uses the toilets on trains stopped at Zurich station. 

Construction workers operating below tracks 10,11,12,13,15 and 16 have reported receiving frequent faecal showers from cracks in the ceiling of the passageway where they are working.

“It is unhealthy, revolting and humiliating to work under those conditions,” Remo Schaedler, co-director of the UNIA trade union in Zurich, told newspaper Tages Anzeiger.

Workers started to complain a month ago, causing the SBB authorities to put Plexiglas panels under the tracks. The problem was not entirely solved, however, as excrement continued dripping down into construction area.

“But it seems the solution is difficult because there has to be a space between the trains’ wheels and the Plexiglas,” said SBB spokesman Reto Kormann.

UNIA and SBB are discussing other options, such as closing the toilets just before a train arrives at Zurich station and opening them again once the train has departed. Another suggestion is to only use the older carriages at the rear of trains, since the construction work is taking place under an area generally occupied by the front end.

Workers have now given SBB an ultimatum to fix the situation completely before Wednesday next week, the Tages Anzeiger reports.