China Railway Construction Heavy Industry Corp. Ltd.
Wayss & Freytag Ingenieurbau AG
ESCO Consultant & Engineers Co., Ltd.
Eiffage Infra-Nordwest GmbH
Kiuchi Construction Co., Ltd.
Bochumer Eisenhütte GmbH & Co. KG
Shenzhen Zhongtieerju Engineering Co. Ltd.
China Railway 16th Bureau Group the 5th Engineering Co., Ltd.
ALWAG Tunnelausbau GesmbH
Hitachi Construction Co. Ltd.
China Railway 19th Bureau Group 2nd Co., Ltd.
Nippon COMSYS Corp.Tokyo-to, Japan