The bridge girder laucnher, gantry crane and transporter belong to the large-scale duty machinery, they must be walking type bridge girder launcher
installed according to the erecting priciple.
1,firstly,erecting the bridge girder launcher by truck crane according to the 《Crane operation safety regulations for technical operations》strictly,
the crane shouldn't be replaced by loader
2,the installing site should be closed , non-workers mustn't be allowed to come into. The wokers must wear safety helmet who come into site ,
and the person must tie safety belt who work om the truss girder.
3,the installing site  
4,the commader and technician are responsible for the installing site, according to the priciple (from down to up , and from midlle to both side) 
to insall the parts in order, and checking strictly.