Section 70(6)(d) in West Bengal Municipal (Building) Rules, 2007
(d)in case the parking area in the basement is less than 1000 sqm, only one ramp will be required. In case the parking area in the basement is more than 1000 sqm at least two ramps shall be provided. Width of each ramp shall not be less than 3.5 mtrs. and the slope shall not be steeper than one vertical to six horizontal and the distance between the ramps shall be such as may be determined by the Municipal Authority :