Standard for Fire Safety in Rapid Transit Systems - Singapore Civil ...

(iv) The minimum width and capacity of exit
passageway shall comply with the
requirements as provided in Cl.2.2.3.7,
Cl.2.2.4.6 and Cl.2.2.5.4, and
(v) Changes in level along an exit passageway
requiring less than two risers shall be by a
ramp complying with the provisions under
Cl.2.2.5.10, and
(vi) If the exit staircase which connects to the
internal exit passageway is pressurised, the
internal exit passageway shall not be naturally
ventilated but shall be mechanically ventilated,
and it shall be pressurised to comply with the
requirements in Section 2.6.
(c) External exit passageway
(i) An external exit passageway may be used as a
required exit in lieu of an internal exit
passageway, provided that the external wall
between the exit passageway and the rest of
the floor space may have ventilation openings
of non-combustible construction, fixed at or
above a level 1.8m, measured from the
finished floor level of the passageway to the
sill level of the openings and such ventilation
openings shall be located not less than 3m
from any opening of an exit staircase, and
(ii) An external exit passageway may not be
subjected to the limitations of a maximum of
two exit doors opening into the exit
passageway, and
(iii) An external exit passageway may be roofed
over provided the depth of the roofed over
portion shall not exceed 3m to avoid smoke
logging, and
(iv) An external exit passageway may be enclosed
on the open side by only a parapet wall or solid
balustrade of not more than 1m in height, and
(v) Exit doors opening into an external exit
passageway shall have fire resistance for at
least half an hour and fitted with automatic
self-closing device.
External exit
passageway
Standard for Fire Safety in Rapid Transit Systems 33