N.Y. ADC. LAW § 27-377 : NY Code - Section 27-377: Ramps

Interior  or exterior ramps may be used as exits in
  lieu of interior or  exterior  stairs  provided  they  comply  with  the
  applicable  requirements  for  interior stairs in section 27-375 of this
  article  or  exterior  stairs  in  section,  27-376  of   this   article
  respectively, and with the following:
    (a) Capacity. The capacity of ramps shall be as listed in table 6-1.
    (b)  Maximum  grade. Ramps shall not have a slope steeper than 1 in 8,
  except that in buildings classified in occupancy group H the slope shall
  not exceed 1 in 12, and except as provided in subchapter eight  of  this
  chapter for places of assembly.
    (c) Design.
    (1)  CHANGES  IN  DIRECTION.  Ramps shall be straight, with changes in
  direction being made at level platforms or landings, except  that  ramps
  having  a  slope  not  greater  than  one in twelve at any place, may be
  curved.
    (2) LENGTH. The sloping portion of ramps shall be at least three  feet
  but not more than thirty feet long between level platforms or landings.
    (3)  PLATFORMS.  Level  platforms or landings, at least as wide as the
  ramp, shall be provided at the  bottom,  at  intermediate  levels  where
  required, and at the top of all ramps. Level platforms shall be provided
  on each side of door openings into or from ramps having a minimum length
  in the direction of exit travel of three feet, and when a door swings on
  the platform or landing a minimum length of five feet.
    (4)  DOORS.  Door  openings  into  or from ramps shall comply with the
  requirements for stairs in subdivision (g) of  section  27-375  of  this
  article. No door shall swing over the sloping portion of a ramp.
    (5)  GUARDS  AND  RAILINGS.  Guards and railings of ramps shall comply
  with the applicable requirements of subdivision (f) of section 27-375 of
  this article except that only ramps having a slope steeper than  one  in
  twelve  need comply with the requirements for handrails and intermediate
  handrails shall not be required.
    (6) SURFACE. Interior ramps exceeding a slope of one in  ten  and  all
  exterior ramps shall be provided with nonslip surfaces.
    (7)  Ramps  for people having physical disabilities shall additionally
  comply with the requirements of reference standard RS 4-6.