... in use HDG steel grid/steel grating for ditch1.Comprehensive type and broadest range in dimension.1.1 Material Q235 , or ... , 34, 34.8, 35.3, 40, 60, 80……Pitch of cross bars(mm)38.1, 50, 50.8, 70, 75, 80 ... above.1.4 Grating type: flat bar: plain type, plain I type, serrated type, serrated I type; cross bar: round type and square twisted type. HDG steel grid ...