Kenya on Wednesday signed a $620-million agreement to build a 530 km highway from its east coast to the centre of the country, part of a campaign to boost its role as a regional trade hub.
A consortium including a unit of South Africa's Group Five and the Development Bank of Southern Africa will work with the state.
Cabinet Secretary James Macharia said in a statement the road would link Lamu on the coast to Isiolo, north of Nairobi, via Garissa.
The consortium will design, build, finance, maintain, operate and transfer the highway. Work is due to start in mid 2018 and be completed within four years.
Kenya wants to build up a role as a regional trade and transport hub, serving as a link to landlocked countries such as Burundi, Rwanda and Uganda.
It is seeking more private investment to maintain the pace of spending on highways, railways and other vital assets while reducing its budget deficit.
The Public Private Partnership model has been touted as a promising route to fund new infrastructure across Africa, a continent that struggles with poor transport networks.
"The signing of this agreement shows continued confidence of international investors and its economic stability," Macharia said.
Macharia said the highway was part of a 2 000 road network linking a planned port in Lamu with the rest of Kenya and neighbouring South Sudan and Ethiopia, of which 505 km is already complete.
He added that the consortium will operate and maintain the road for 25 years after it is opened.
President Uhuru Kenyatta, who was sworn in on Tuesday for a final five-year term, campaigned on what he presented as his record of aggressive economic development drive, citing among other things, new roads.