15 cm and 100 cm

15 cm and 300 cm

30 cm and 450 cm

60 cm and 300cm

less strength

difficulty in construction

difficulty in transportation due to heavy weight

less life

rectangular section

circular section

standard form of egg shaped sewer

modified egg shaped section

is economical than circular section

provides self cleansing velocity at low discharges

is more stable than circular section

is easy to construct

grade of sewer

length of sewer

hydraulic mean depth of sewer

roughness of sewer