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

(c) Smoke obscuration levels
Smoke obscuration levels should be continuously
maintained below the point at which a sign internally
illuminated at 80 lux is discernible at 30m and doors and
walls are discernible at 10 m. This is equivalent to a light
attenuation coefficient of 0.267 per m.
(d) Air velocities
Air velocities in the enclosed trainway should be greater
than or equal to 0.76m/s and less than or equal to
11.18m/s;
(e) Noise levels
Maximum of 115dBA for a few seconds, maximum of
92dBA for the remainder of the exposure.
G.3 Geometric Consideration
Some factors that should be considered in establishing a tenable
environment in stations are as follows:
(a) The evacuation path requires a height clear of smoke of at
least 2m. The current precision of modeling methods is
within 25 percent. Therefore, in modeling methods a
height of at least 2.5m should be maintained above any
point along the surface of the evacuation pathway.
(b) The application of tenability criteria at the perimeter of a
fire is impractical. The zone of tenability should be
defined to apply outside a boundary away from the
perimeter of the fire. This distance will be dependent on
the fire heat release rate and could be as much as 30m
Smoke
obscuration
levels
Air velocities
Noise levels
Standard for Fire Safety in Rapid Transit Systems G-4