Page 4 - Air Quality In Tunnels

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How is air quality managed
in the Cross City Tunnel?
Air quality is managed via a ventilation
building located west of Harbour Street,
between the existing Harris Street and
Market Street viaducts above the eastern
side of Darling Harbour.
The tunnel has been designed to provide
better air quality during an incident such
as a traffic accident or vehicle breakdown
and features a unique “third” tunnel
(ventilation tunnel) located beneath the
two traffic tunnel tubes.
In normal operating conditions, air travels
east in the eastbound tunnel before being
directed into the westbound tunnel to travel
to the ventilation building. A ventilation
tunnel has been constructed beneath the
road tunnels for use during heavy traffic and
other incidents. At these times, air from the
eastbound tunnel will be transferred into
the ventilation tunnel and expelled via the
ventilation outlet.
Other features of the ventilation
system include:
· Jet fans along the ceiling of the tunnels
and access ramps to control air flow.
· A main underground ventilation building
at the western end near Druitt Street.
· A ventilation cross-over passage and ventilation
station at the eastern end of the main tunnels.
· A bypass fan station at the western end
that generates airflow in the bypass
ventilation tunnel.
Air quality monitoring
Air quality in-tunnel monitoring is undertaken
at various locations. The tunnel is operated
to ensure air quality levels stay within the
goals set by the former Minister for Planning.
Air quality information from in-tunnel
monitors, as well as relevant meteorological
data such as wind factors, is available
on the tunnel operator’s website at
The Cross City Tunnel
The Cross City Tunnel links Darling Harbour
to Rushcutters Bay through separate east
and westbound tunnels, avoiding up to 18
sets of traffic lights. From the west, you can
access the Eastern Distributor directly to the
airport. Coming from the east, you can avoid
city traffic and access the harbour crossings.
The Cross City Tunnel improves air quality
by taking cars and their emissions off
surface streets. Better air quality in Central
Sydney was one of the key objectives of the
Cross City Tunnel. Studies show air quality
is significantly improved, with up to 40,000
vehicles a day travelling in the tunnel instead
of using existing streets.
Inside the Cross City Tunnel