The Kenya National Highways Authority has warned motorists not to use the Athi River-Machakos road service lane.
In a statement on Friday, the Authority said a section of the embankment slopes has eroded to the heavy rains and is a danger to motorists.
It urged motorists using the road near Green Park estate to exercise caution.
KeNHA, however, said that the main carriage is operational, and motorists should still exercise caution as they use it.
"KeNHA advises motorists plying the Athi River - Machakos Road near Green Park estate to exercise caution. The embankment slopes have eroded, posing risks to the service road.
"The main carriageway remains open, however, due to the tenuous conditions, please refrain from using the service road. Motorists are advised to prioritize safety when using the main carriageway and to proceed with caution," the Authority said on X.
On Thursday, KeNHA issued a traffic advisory to motorists plying Mombasa Road particularly those around the Konza area.
KeNHA noted that there was heavy traffic around the Konza area, urging motorists to be patient.
The authority said it was doing its best to hasten the construction along the route which is the cause of the traffic snarl.
"The Authority understands the inconvenience and assures you that efforts are being made to expedite the process," KeNHA said.
Motorists are to expect a smooth flow of traffic along the route by the weekend, KeNHA said.
"Please drive carefully and follow all traffic regulations. We anticipate smoother traffic flow by the weekend."
On Wednesday, the Kenya National Highway Authority advised motorists to refrain from attempting to cross the Athi River Bridge until the water levels recede to safe levels.