Why Dongo Kundu Bypass Has This Huge Tunnel Near Mombasa Airport

A distinctive steel overhead canopy along the Dongo Kundu Bypass (Mombasa Southern Bypass) in Mombasa has sparked widespread public curiosity online. Motorists frequently inquire about the structural purpose of the extended covered enclosure and the reason is as interesting as modern civil engineering can get.

Dongo Kundu Bypass, also known as the Mombasa Southern Bypass, passes close to the airport as it connects the mainland side of Mombasa with the South Coast. The road therefore had to be built within a corridor where normal highway traffic operates alongside aviation activity.

The bypass is one of the best engineered roads in Kenya. Here is Mteza Bridge. /CK

The result is a structure that looks unusual from inside a vehicle. Instead of the road remaining completely open beneath the flight path, a long canopy covers the carriageway.

The structure is not uniform along its entire length. In the first section, vehicles travel beneath a steel frame with columns supporting the overhead canopy while the sides remain largely open. Further along, the structure becomes more enclosed, with concrete barriers forming the sides of the carriageway beneath the canopy.

Civil engineers integrated the reinforced steel structure primarily as a jet blast shield. Aircraft descending or executing takeoffs at low altitudes generate high-velocity turbine exhaust capable of destabilizing passing vehicles, shattering windshields, or scattering debris across active traffic lanes.

The tunnel. /Nation

The structure also mitigates driver distraction along the busy dual carriageway. Low-flying commercial airliners overhead can startle motorists, potentially causing sudden braking or sudden lane departures. The opaque enclosure keeps drivers focused entirely on the road ahead.

In addition, the canopy serves crucial aviation safety and security functions for Kenya Airports Authority operations. It prevents vehicle headlight glare from interfering with pilots during night approaches while securing the airport perimeter against unauthorized physical access or visual exposure.

Constructed during the Kenya National Highways Authority Dongo Kundu project, the enclosure accommodates heavy freight traffic bypassing Mombasa Island. The specialized design balances essential urban transport flow with strict international aviation safety standards.

Read why some motorists still prefer using the crowded Likoni ferry instead of using this breathtaking bypass.