The much-awaited Jomo Kenyatta International Airport (JKIA)-Westlands expressway was on Wednesday commissioned by President Uhuru Kenyatta.
The Sh65 billion project was set to commence in August but was pushed to October and construction is set to begin soon.
The 18.586-kilometre road project will start at JKIA and terminate at James Gichuru, along Waiyaki Way, in Westlands.
The mega project will be undertaken by the China Road and Bridge Corporation (CRBC) on a public-private partnership (PPP) basis.
Unlike ongoing projects, where the government has secured loans to fund construction, the government says the PPP framework agreement will see CRBC invest its own money and later recoup its investment from toll fees paid by motorists using the road.
Motorists will have the option of using the express way to escape the heavy traffic jams at a fee or toll charges to help the private firm building the road recover its investments.
But those using the lower section of the double-decker highway will be spared the toll charges.
The bus rapid transit (BRT) system is one of the special features of the planned highway, which will involve construction of a dedicated lane for large-capacity buses to ease congestion.
The project has delayed for nearly a decade. The first construction attempt collapsed when the World Bank questioned its suitability and cut financing.
It will be elevated near Ole Sereni Hotel through the City Center along Uhuru highway up to James Gichuru junction and will be completed within two years.
The proposed elevated dual carriageway is to be built in three phases beginning with the first 6.5 kilometres running from JKIA to Likoni Road and the Southern Bypass interchange.
The second stretch of 12km will connect Likoni Road to James Gichuru Road junction on Waiyaki Way in Westlands, while the last section will run from James Gichuru Road to Rironi, on the Nairobi-Nakuru highway.
The road will come with multiple interchanges at intersections on Popo-Kapiti, Lang’ata-Lusaka, Bunyala, Rhapta and James Gichuru roads.