The proposed construction of two overpasses and a series of road interchanges linking Ngong Road to Nairobi's Central Business District (CBD) will soon get underway.
The Kenya Urban Roads Authority (Kura) said the project, estimated to cost Sh2.9 billion, will commence early next year and is expected to be completed in 2023.
The project will involve the construction of a viaduct at Valley Road/Kenyatta Avenue from Integrity Centre to Serena Hotel.
Viaduct is a type of long bridge or series of bridges, usually supported by a series of arches or on spans between tall towers.
There will also be an interchange at Ngong/Nyerere Road and an overpass at Upper Hill/Haile Selassie and associated road networks from Milimani Law Courts to Lower Hill Road.
State House road will be refurbished while Nyerere Road will be turned into a dual carriage way.
During a draft presentation of the construction work, resident engineer Benjamin Asin said the project will be fully funded by the National Treasury.
Asin said two elevated carriage ways will be erected; one from Integrity Centre to Serena hotel and another one on Milimani Close.
"The works should begin sometime next year. At the moment we are doing preparatory assessment of relocation of works planning and geo-technical investigations," said Asin.
The process of identifying and relocating service providers is currently ongoing after the project tender was awarded to China Roads and Bridges Corporation-Kenya with Kura as the overseer.
To minimise traffic disruption, Asin said they will work at night and first construct slip roads, where traffic will be directed before embarking on the elevated carriage ways.
The two elevated carriageways have been designed in such a manner that they will approach the Sh57 billion Mombasa-Nairobi Expressway at lower levels and into the CBD through Haile Selassie and Kenyatta Avenues.
"There will be no connection because one is for traffic that is going express so we do not want to mix, as traffic approaches the Expressway, it will go down and into the city," he said.
Provisions have also been made to cater for closed lanes, cycle tracks and side lanes, including two Bus Rapid Transport corridors along Haile Selassie and Kenyatta Avenues.
During construction, no building will be demolished as Kura will use space reserved for road expansion, except for strips of land owned by All Saints Cathedral, the Milimani Commercial Court and along Nyerere Road.
The improvement works will consist of the removal of the existing two-lane bituminous road and widening of the same to a two-lane two-way carriageway with a median separator, cycle tracks, footpaths, drain and street lighting.
Mr Asin added that bituminous construction works will also include construction of service roads, slip roads and acceleration and deceleration lanes at specific stretches and median breaks.
Concrete works include rehabilitation of existing cross drainage works and construction of new drainage structures.
Kura is also set to construct another overpass link road, around Haile Selassie Avenue which is expected to divert traffic from the city centre, consequently reducing congestion in the CBD.
The flyover will link Enterprise Road to Central Business District to ease traffic on Mombasa Road and pass over the Nairobi Railway station and Wakulima Market.
The flyover was captured as a missing link and a priority project in the Nairobi Integrated Urban Development Master Plan 2030 (NIUPLAN).
The road will ease traffic flow in Jogoo Road and Landhies Road, while offering an infrastructure solution to Nairobi CBD's traffic problems.
The overpass is set to take up the space occupied by the old Wakulima Market with traders to be relocated to the new Wakulima market along Kangundo Road, which is almost complete.