Airports — Fast Flow Group

Airports

Drainage for
landmark
terminals

Airport terminals present some of the most demanding drainage engineering challenges — vast roof areas, complex structural systems, strict regulatory requirements and zero tolerance for drainage failure. Fast Flow has completed siphonic drainage systems for major airports across Asia Pacific and beyond, from Singapore's Changi to Beijing Capital, Guangzhou Baiyun, and airports throughout Southeast Asia and Australia.

Featured Project · Beijing, China

Beijing Capital
International Airport

2-Tier

20yr primary · 100yr secondary

Hydraulic
Jump

Special containment design

Arch.

Seamless integration into architecture

Beijing Capital International Airport · Organic 3D curved roof structure · Multiple north-south gutter segments

Challenges

Beijing Capital Airport's organic 3D curved roof is divided by multiple north-south gutters into segments. These gutters, positioned above the space frame structure, are limited to just 250mm depth with slopes varying both along and across the gutter — creating extreme hydraulic complexity.
The roof required a 2-tier drainage design: primary drainage sized for a 20-year return period, with controlled overflow to a lower gutter for 100-year events. Managing two concurrent flow regimes within a single shallow gutter system presented a formidable design challenge.
High-velocity gutter flow, bi-directional slopes, hydraulic jump formation at flat drainage sumps, and strict containment of overflow — all had to be solved simultaneously within the 250mm gutter depth constraint.

Solutions

Through meticulous 3D analysis of water flow at every gutter location, Fast Flow designed off-centred sumps that exploit the roof profile to create a controlled drop, breaking flow momentum before it reaches the siphonic outlet.
The extent of hydraulic jumps was calculated precisely at each location, and bespoke cover plates were designed to contain the jumps within the gutter depth — preventing overflow at the primary drainage stage.
Additional strategically placed cover plates manage the controlled overflow, channelling excess water safely to the lower tier. All these specialised features work in concert within the 250mm gutter envelope.

Achievement

The Beijing Capital Airport siphonic drainage design stands as a benchmark of specialised hydraulic engineering: combining high-efficiency siphonic systems with precision 3D water flow analysis and creative open-channel solutions. It exemplifies Fast Flow's ability to develop entirely customised solutions tailored to problems that are unique to each project — solving what others cannot.