Key features of the Nairobi-Mau Summit highway - what to expect

An artist impression of the project/COURTESY

The upcoming Nairobi–Nakuru–Mau Summit and Nairobi–Maai Mahiu–Naivasha road upgrade projects is set to showcase one of the country's most ambitious infrastructure ventures under the Public–Private Partnership (PPP) framework.

The project, a Privately Initiated Proposal (PIP) by the China Road and Bridge Corporation (CRBC) in partnership with the National Social Security Fund (NSSF), will see the transformation of the vital A8 transport corridor that links Nairobi to the Rift Valley and Western Kenya.

Under the supervision of the Kenya National Highways Authority (KeNHA), the project will cover a total of over 230 kilometers, spanning from Rironi to Mau Summit (A8) and branching off to Naivasha via Maai Mahiu (A8 South).

A8: Nairobi–Nakuru–Mau Summit Upgrade

The A8 section, stretching approximately 175 kilometers, will undergo major reconstruction and expansion.

The Nairobi–Naivasha stretch covering 58.9km will be upgraded into a dual 4-lane carriageway.

The Naivasha–Nakuru West segment covering 58.9–123km will expand to a dual 6-lane carriageway, easing congestion through high-traffic zones.

The Nakuru–Mau Summit extending from 123–175.7km section will feature a dual 4-lane carriageway, improving access to the western economic corridor.

In Nakuru town, a full viaduct section will be constructed to maintain smooth urban flow.

The project will also include the establishment of six toll stations along the A8 route, enhancing sustainability and maintenance financing under the PPP model.

A8 South: Nairobi–Maai Mahiu–Naivasha Road

The A8 South link, spanning 56.8 kilometers, will complement the main highway and enhance regional connectivity.

The Nairobi–Maai Mahiu segment will be upgraded to a dual 4-lane carriageway, incorporating climbing lanes to navigate steep terrain.

The Maai Mahiu–Naivasha stretch will be rehabilitated and resurfaced, ensuring durability without lane expansion.

Two toll stations will be installed along this section.

Safety will be a key focus, with new features addressing fog-prone zones, steep gradients, improved drainage, road signage, and lighting.

Motorists using the upcoming road will pay a base toll rate of Sh8 per kilometre, according to disclosures by KeNHA.

The toll, which will rise by one per cent annually, was a decisive factor in selecting the CRBC–NSSF consortium as the preferred bidder under a 30-year concession. 

The Sh180 billion project, which could peak at Sh194 billion, will begin before January 2026 and completed within two years. 

KeNHA’s selection committee noted that the consortium’s offer undercut a rival bid by Shandong Hi-Speed Road and Bridge International, which had proposed a higher Sh10 per kilometre rate with a three per cent yearly escalation.

It will also include 15 interchanges, eight footbridges, 25 kilometres of service lanes, eight wildlife crossings, 41 underpasses, 41 U-turns, and 118 bus bays, all designed to improve connectivity and safety.

The base toll rate applies to passenger cars and 4WD vehicles from the first operational year in 2028.

Annual adjustments will help cushion against inflation and exchange rate fluctuations, though the government has indicated it will conduct further public consultations to ensure long-term affordability. 

According to the project tender brief, “GoK should negotiate a competitive toll tariff as per stakeholder engagement findings,” underscoring the emphasis on inclusivity and public input in determining final rates.

The project will be financed through a mix of 75 per cent debt and 25 per cent equity, both denominated in shillings.

The NSSF’s participation marks a milestone in local institutional investment in major national infrastructure, while the CRBC–NSSF consortium will shoulder traffic and revenue risks, shielding taxpayers from potential financial exposure. 

To maintain affordability, the Evaluation Committee has recommended pass-through mechanisms for foreign exchange and operational costs and called for a revised traffic forecast of three to four per cent annual growth instead of the initial conservative one per cent, a move expected to support lower toll charges over time.