pipe roof culvert box advancing method
Junction Box， Connection Box， Connector Box
Changing flat roof to slope roof
diagonal ridge for hip roof，vertical ridge for gable roof
flat- roof-to- slope-roof
flat-roof-to-slope-roof
flat-roof-to-sloping roof
roof pressure roof weight
roof prism (=roof-angle prism)
box-girder and box-pier
box-on-box type substructure
box-type negative-pressure boiling dry-box