The State plans to reroute the 13-kilometre Narok-Mai Mahiu section that collapsed during rainy seasons.
Kenya National Highway Authority director-general Peter Mundinia said the agency is mulling a redesign of the road as it is prone to damage during rainy seasons due to volcanic faultlines underneath the highway.
The road was washed away twice with a span of a week, disrupting traffic headed to southern Nyanza, Bomet and Tanzania from Nairobi via Narok.
“It (re-routing) will be the solution to the problem we are facing at the moment,” said Mr Mundinia.
“During underground erosion, the volcanic ash normally becomes wet, bringing about the instability of the topsoil, which then collapses.”
Transport on the busy road was once again disrupted Monday morning after the section that was cut-off last week but later repaired collapsed again.
Last Wednesday, motorists plying the route spent the night in the cold after a section was washed away by floods. The road was cut off, with a fissure extending more than three kilometres uphill and 200 metres on the opposite end.
China Communications Construction Company engineers immediately embarked on major repairs of the road.