The Japan International Cooperation Agency (JICA) has granted Nairobi funding of £20 million to transform the city's Ngong road into a dual carriageway.
The upgrading works are expected to begin in the next few months, with a projected completion date of February 2015.
The road, which leads to the Central Business District and the south-west suburb Karen, is a constant source of gridlock for the city’s motorists, particularly the stretch between Adams Arcade roundabout and Kenyatta Avenue crossroad.
The JICA say that the project will result in a significant decrease in congestion and is in line with the capital's rapidly-rising population.
Kenya loses over $500,000 a day due to traffic congestion in the greater Nairobi area, primarily due to non-productive time spent on the road, according to a recent study by IBM Corporation.