in order to combat regular flash flooding in kuala lumpur (sometimes twice yearly) caused by two overflowing rivers in the north of the city, engineers decided to construct a huge stormwater tunnel to drain the water from it’s source to a reservoir, underground. they then thought, `why not kill two birds with one stone?’, went back to the drawing board and managed to alleviate another of the city’s problems: major traffic congestion.

in a circular nutshell, here’s the amazing solution…

the whole tunnel system is 9.7km long – only the 4km of tunnel that runs under the heavily congested roads of the city is split into the three sections you can see above.

this system has three modes of operation.

mode 1: no storms – the tunnel is used purely as an underground motorway on the top two levels.

mode 2: moderate storms – traffic is still permitted to use the top levels and any flood water is channeled through the lower level.

mode 3: major storms – all traffic is cleared from the tunnel and water surges through all 3 levels.