Section 61(10)(mm) in The West Bengal Factories Rules, 1958
(mm)Ramps with a slope of not more than 1 in 10 may be substituted for requirements of staircase. For all slopes exceeding 1 in 10 and wherever the use is such as to staircase. For all slopes exceeding 1 in 10 and wherever the use is such as to involve danger of slipping, the ramp shall be surfaced with non-slipping material.