Rironi-Mau Summit Road: Tracing the Ksh.184B, 233km stretch to ease decades of congestion

The billion-dollar highway is expected to transform a long-congested and accident-prone route linking Nairobi to Western Kenya and the East African region. With a 2027 completion timeline, we explain what is being built and how it is being funded. 

Since the construction launch, activity on the ground has picked up. 

“A lot of work is in mobilisation of equipment, the sites for the equipment and getting the contractors on site,” says Roads and Transport Cabinet Secretary Davis Chirchir. 

The 233-kilometre road construction and dualling project is being carried out by two major Chinese concessionaires - the China Road and Bridge Corporation and Shandong Hi-Speed Road and Bridge International.  

“When we were discussing and looking at our time frame we realized that if we invest with only one, the portfolio will go beyond a billion U.S dollars and for these Chinese contractors, their approval in their own countries, when it is beyond a billion dollars, then they have to have certain levels of approval which would have taken too long,” Roads Principal Secretary Eng. Joseph Mbugua says.

And unlike past road projects, a fast-tracking model is being applied as the government targets 2 years timeline, as agreed in the contract. 

“From February, we will be having 12 gangs from both concessionaires to ensure that we deliver the road by April or May 2027,” Chirchir says. 

The 12 gangs include organized work teams operating simultaneously on different sections of the highway.

Traditionally, the journey from Nairobi to Nakuru has been a nightmare, as Kenyans have repeatedly spent nights on the roads because of the massive traffic snarl-up right after Rironi. But the government now says that starting December 2027, this is bound to change. 

The Rironi–Mau Summit Road will start at Rironi as a four-lane dual carriageway up to Naivasha. From Naivasha to Nakuru, where traffic volumes are highest, the highway will widen into six lanes on each side to accommodate heavy commercial and passenger traffic.

Through Nakuru town, the road will be elevated. This design is intended to bypass city congestion and improve safety for local road users. From Nakuru to Mau Summit, the highway will revert to a four-lane dual carriageway. 

“We ask for patience. This is being done for the good of tomorrow, and we are going to be courteous to ensure that contractors do provide alternative routes when a road is closed,” says Chirchir.

The project is split into two phases. In the first phase, the China Road and Bridge Corporation, in partnership with Kenya’s National Social Security Fund (NSSF), will expand two existing sections. These are the A8 stretch, running from Rironi through Naivasha to Gilgil, and the A8 South road, which runs from Rironi through Mai Mahiu to Naivasha. This first phase will be done at a cost of 863 million dollars.

The second phase to be undertaken by Shandong Hi-Speed Road and Bridge International covers the single-lane road from Nakuru to Mau Summit. Expanding this 94-kilometre section will cost about 678 million dollars. 

The two phases will form a continuous, high-capacity highway linking Nairobi to western Kenya and the larger East African region. Construction is expected to be completed by the end of 2027 at a total cost of 1.4 billion U.S. Dollars, or about Ksh.184 billion.

“2027 siku ya madaraka tarehe moja mwezi wa sita mimi nakuja kufungua hii barabara ikiwa imekamilika,” President William Ruto previously stated. 

“We always elect our leaders so they can bring development to our regions, so if the president is going to use this project to lure us as voters we have no problem. The problem is when our leaders come to lure us through tribal politics, through promises that never come to fruition, but if it is through projects, we really welcome the idea,” remarks James Wainana, a road user. 

After completion, the 2 concessionaires will operate the road for 28 years to recover their investment and earn returns before handing it back to the government. The entire corridor will operate as an open toll road. 

“We are looking at about 8 shillings per kilometre for small vehicles, and there is a factor of how it is computed when you are doing the big trucks,” says the roads CS. 

This means that if you are to drive from Rironi to Mau Summit once the road is complete, you would pay a total of Ksh.1400. 

“We will really improve the adjoining roads to ensure that there are adequate alternative routes for those clients who may choose not to use this road,” Chirchir assures. 

The importance of the Rironi–Mau Summit Road lies in what it unlocks. 

“Biashara zetu ambazo watu wa nyandarua, watu wa Rift valley wale wanlima mahindi, zitaweza kufika on time kwa sababu ya upanuzi na dual carriage ya hii barabara. Si kama hapo mbeleni ambayo ilikuwa njia moja ambayo kukiwa na msongamano unapata viazi zimeharibika, sukuma zimeharibika,” says businessman John Kombo. 

This highway is a key part of the Northern Corridor and is the main transport artery linking the Port of Mombasa to Nairobi, western Kenya, and landlocked neighbours such as Uganda, Rwanda, and the Democratic Republic of Congo.  

By upgrading a historically congested and dangerous route, the project is expected to drastically cut travel times and improve Kenya’s position as East Africa’s trade and logistics hub

“It's really upon us to ensure that we do not give in to competition out of Djibouti port out of daresalaam port because don’t forget that if our competitors have got easier access to the market, easier movement because of good infrastructure, they definitely take that competitive advantage out of Kenya,” the Roads & Transport minister posits. 

To support this massive upgrade, the government has also accelerated work to expand the westlands to Rironi road from a four-lane to a six-lane dual carriageway. 

The James Gichuru to Rironi highway is critical in easing traffic flow from Nairobi onto the Nakuru highway. This project is being undertaken by China Wu Yi at a cost of about Ksh.20.4 billion, and is fully financed by the government of Kenya. It is now about 82 per cent complete according to the Kenya National Highways Authority.

Together with the Rironi–Mau Summit Road, it will remove one of the biggest bottlenecks on the corridor.

“We’ll construct outside the new roads before we come and rehabilitate where the current road is sitting, so we’ll not see much congestion,” Chirchir says. 

And there are alternative routes for those travelling to areas like Narok, Bomet, Kisii and even Migori.

As Christmas travel reaches feverpitch, the Ngong-Suswa road, completed about two weeks ago, will be a critical alternative to Kenyans travelling to the South Rift.

This project comes after the termination of an earlier agreement with a consortium led by France’s Vinci earlier in the year. The new deal was announced during President Ruto’s state visit to Beijing in April 2025.