CONCRETE PIPE Maximum Allowable Openings Big Box Manhole Recommended Maximum Opening Sizes Span/ Rise 500 1000 1500 2000 2500 3000 3500 4000 Maximum Pipe Size Plastic only (Up to 450 mm) 675 1050 1500 1950 2100 2700 3000 Opening Provided As required 990 1434 1967 2500 2640 3389 6707 Maximum Box Size 1200 x 900 1800 x 1200 2440 x 2440 3000 x 2400 3000 x 2400 Opening Provided 1550 x 1340 2150 x 1675 2940 x 2940 3500 x 2900 3500 x 2900 Bold text indicates the need for multiple sections to meet internal height requirements. As with all vertically oriented box structures, the following limitations apply: • The maximum allowable openings depicted in the adjacent illustration are for ‘dead end’ or ‘straight through’ configurations only. For multiple pipe or box connections, it is recommended that at least 300 mm of wall length remain on either side of any corner. Dual openings can also be accommodated depending on size and orientation. A minimum distance of 300 mm is typically recommended between openings. For large sized openings (i.e. openings spanning the entire side of the box section), a concrete beam is often left in place for support during shipping and handling of the piece. This beam is removed in the field with cutting and coring equipment once the manhole has been placed. Angled connections are typically accommodated by providing an oversized opening. For pipe connections located on the corner of the vertical box section manhole, please contact your local Lafarge representative for design assistance and/or recommendations. • • • PAGE 54 LAFARGE PIPE eMANUAL