(S3.12) – (S4.5)SFLIGHTS CONSISTING PARTLY OF STRAIGHT AND PARTLY OF TAPERED TREADS(S3.12) The requirements of S3.12 as regards tapered treads will be met where the stair is constructed inaccordance with BS585: Part 1: 1989, Appendices B1 and B3, irrespective of the material of construc-tion or whether it contains open rises.FLIGHTS CONSISTING WHOLLY OF TAPERED TREADS(S3.15) The requirements of S3.15 will be met where the flight consists wholly of tapered treads forming ahelix or spiral and is constructed in accordance with BS5395: Part 2: 1984. Where such a flight formsan escape stair the category of the stair must be in accordance with the table to this specification -Table to (S3.15):Helical or spiral flights forming an escape stairAppropriate capacity not exceeding - [Note 1]Stair category [Note 2]10B25C [Note 3]50D [Note 3]100E [Note 3]Notes:1.Appropriate capacity to be calculated in accordance with Part E.2.Refer to Table 2 of BS 5395: Part 2: 1984.3.Handrails must be provided on both sides.INDUSTRIAL STAIRS AND FIXED LADDERS(S3.26) The requirements of S3.26 will be met by the use of industrial stairs or fixed ladders in the circum-stances described in, and constructed in accordance with, BS5395: Part 3: 1985; or BS4211: 1994; orby a Type A Spiral or Helical Stair constructed in accordance with BS5395: Part 2: 1984.STAIRS AND FIXED LADDERS IN AGRICULTURAL BUILDINGS(S3.27) The requirements of S3.27 will be met by the use of stairs or fixed ladders in the circumstancesdescribed in, and constructed in accordance with, BS5502: Part 80: 1990.PEDESTRIAN PROTECTIVE BARRIERS(S4.3) The requirements of S4.3 will be met where the loads are calculated in accordance with BS6399: Part1: 1996.VEHICLE PROTECTIVE BARRIERS(S4.5) The requirements of S4.5 will be met where the loads are calculated in accordance with BS6399: Part1: 1996.Amdt December 1999: 20S