Kenya National Highways Authority figures released in 2018 placed Mombasa’s Dongo Kundu Bypass at the top of the country’s road-cost rankings, with the Mwache–Mteza section emerging as the most expensive stretch per kilometre.
KeNHA said the nine-kilometre Phase Two of the bypass carried a total price tag of Sh24 billion, which works out to Sh2.7 billion for every kilometre. The authority said two sea bridges, covering 2.1 kilometres in total, were the main reason for the high cost.
The disclosure landed amid growing public concern over the price of major infrastructure projects and their effect on public finances. The Treasury had allocated Sh116 billion for road construction that year.
KeNHA said Mombasa remained the most expensive corridor for road building because of difficult terrain and the need for heavy reinforcement. The authority said those conditions also affected other sections of the Mombasa bypass, which is being built under the Mombasa Port Area Road Development Project to reduce congestion around the port.
Phase One of the bypass, the 11-kilometre Miritini–Mwache section opened in June, was priced at Sh1.15 billion per kilometre. KeNHA linked that figure to the terrain and to security features, including a canopy on a one-kilometre stretch along the Moi Airport boundary.
Phase Three, which covers seven kilometres between Mteza and Kibundani, was priced at Sh571.4 million per kilometre. That section includes a sightseeing bay and 88 hectares of mangroves that were replanted along the route.
Other costly projects in Mombasa included the 2.6-kilometre Magongo-Changamwe Road dualling, which stood at Sh930.9 million per kilometre, and the 11.3-kilometre Mombasa-Kwa Jomvu section of the Mombasa-Miritini highway upgrade, priced at Sh532 million per kilometre.
In Nairobi, the proposed Western Bypass was the priciest road per kilometre at Sh965.9 million, with a total estimated cost of Sh17 billion. The 17.6-kilometre Ruaka-to-Gitaru road was to have four lanes, service roads on both sides and interchanges at Wangige, Kihara, Ndenderu and Ruaka.
The bypass was meant to complete the city’s ring road network, with the Northern and Eastern bypasses also set for dualling. The project had first drawn attention two years earlier, when its cost triggered comparisons with the 12-lane Thika Road, which was built seven years earlier at Sh600 million per kilometre.
Other Nairobi projects were also expensive. The 26-kilometre James Gichuru Junction-Rironi Road was costing Sh629.5 million per kilometre, while the 28.5-kilometre Southern Bypass stood at Sh659.3 million per kilometre. KeNHA said the Southern Bypass cost reflected 25 kilometres of service roads, five major flyovers and street lighting.
The authority said land acquisition and the relocation of utilities such as electricity lines, water and oil pipelines, fibre optic cables and sewers pushed up costs in Nairobi. Roads with interchanges and flyovers also cost more, it said, pointing to the three interchanges in Nakuru County, where five kilometres of road cost Sh580.8 million per kilometre.
KeNHA said rural roads were much cheaper, averaging between Sh10 million and Sh150 million per kilometre because land was cheaper, materials were easier to source and utility relocation was less costly.
In its report, the authority said road construction costs varied widely because of several factors, including drainage structures such as bridges and box culverts. It also said urban roads were significantly more expensive than rural ones.
