Commissioning Day: The Engineering of the Ngong Road Flyover

The Ngong Road Flyover at Junction Mall features an approximately 800-metre elevated dual carriageway with a 254-metre steel viaduct section at its core. Steel girders fabricated in Spain support a concrete deck in a composite arrangement that delivers strength with less weight than traditional designs.

Centunion, the Spanish contractor, led the project after completing the similar T-Mall steel flyover on Langata Road. The company brought proven expertise in urban steel structures to this site.

Ngong Road Flyover deck /Handout

The work was funded by a KSh 3.58 billion concessional loan from Spain’s Corporate International Fund. This covered the full scope from foundations through to road surfacing and safety features.

Steel was selected for its high strength-to-weight ratio. The lighter girders permit longer clear spans and slimmer supports. This allowed the design team to use distinctive V-shaped concrete piers that reduce the structure’s footprint at street level and create an open, modern aesthetic beneath the deck.

Construction followed a logical sequence. Concrete foundations and the V-shaped piers went in first. Steel girders were then erected, primarily during night shifts to minimise daytime traffic jams on Ngong Road. The girders rest on bearings that accommodate movement.

Ngong Road Flyover piers before steel girders were installed /Handout

Concrete was cast over the steel frame to form the driving surface. The resulting composite deck handles heavy daily traffic effectively while keeping the overall structure efficient.

The flyover separates main traffic flows from local turning movements at the busy Ngong Road, Naivasha Road and Kingara Road junction. Ground-level lanes serve nearby areas while the elevated section speeds through traffic. It also includes pedestrian walkways, cycling lanes, drainage and lighting.

The project was built to tackle chronic congestion at Junction Mall. It shortens travel times between Ngong Town and the Nairobi CBD and improves connectivity to the Talanta Stadium ahead of AFCON 2027.

KURA officials inspected the deck earlier today, checking the final touches such as road markings. Their checks confirm the engineering work is ready for commissioning by President William Ruto today June 29. Driving on the structure will definitely be an amazing experience.

The flyover combines solid engineering with visual appeal. Its steel girders and V-piers should ease daily commutes and enhance the skyline along this key Nairobi corridor.