The changes will take effect immediately, starting today
The road, popularly known as Thika Superhighway, will have one lane dedicated to Public Service Vehicles (PSVs).
Macharia says the move is meant to address the jam headache into and out of the city.
The Transport CS made the revelation while appearing before the Senate's Roads Committee.
He stated that Thika Road was one of the major roads that had been identified as critical in solving the traffic menace in the city.
"We need more than 900 buses in these six corridors and because we don’t have them, we have opened one corridor, the Thika highway. From Thursday, we are starting the demarcation and dedication of that lane,” Mr Macharia stated.
The programme is also expected to encourage the use of the Bus Rapid Transport (BRT) and discourage the use of PSVs with a low capacity of carrying passengers.