Transport minister James Macharia has announced Wednesday and Saturday as the car-free days in Nairobi.
From February 1, the central business district will be closed to vehicles and traders allowed to sell their wares, especially using the numerous parking lots.
The Cabinet Secretary further said that vehicles for the bus rapid transport system (BRT) will arrive anytime from this date.
Mr Macharia spoke on Monday during a briefing on the progress of the implementation of the BRT system.
Sixty four buses from South Africa will be used in the pilot programme, he said, adding that sectoral representatives were concluding negotiations on the acquisition of 11 trains from Spain, for use alongside the buses.
Twenty more trains will be shipped in due course, Mr Macharia said and noted that for efficiency in the city's transport sector, at least 900 BRT buses are required.
"We have given local manufacturers the templates for the buses. After the pilot programme, the private sector can work with them to manufacture the remaining buses," he said.
The CS also noted that the system will be run by the private sector and refuted claims that the ministry had bribed transporters for compliance.
"We wish to clarify that it is not the county's manufacturers who manufactured the BRT buses used in Tanzania. That is a rumour that is not true," he said.
Principal Secretary Paul Maringa urged cooperation and adherence with guidelines.
"Immense profits will be realised from this development as businesses will be allowed to operate within the CBD," he said of the car-free days.