Ten people will go on trial in China for the subway tunnel collapse last year in East China that killed 21 construction workers.

The collapse happened last November in the tunnel that was under construction in Hangzhou, capital of Zheijang Province.

Investigations by the Work Safety Supervision Administration of Zheijang blamed the collapse on violations of construction rules, problems in the supporting systems and moulding procedures, and project monitoring failure.

The ten defendants include the general manager, the chief engineer quality officer of the project, two officials with the contracted monitoring company, two employees of contractor Fourth Bureau of the China Civil Engineering Group, one officer from Hanghzhou Subway Group, and two officials from Hanghzou’s construction quality supervision station.

Eleven other people, mostly officials with the project contractor, received administrative punishment, according to local authorities.

The collapse cost 49.6M yuan (US$7.3M) in economic loss and triggered safety overhauls in subway projects all over China.