Transport has been paralysed on Thika-Garissa road after sand transporters blocked the highway.
The sand transporters are protesting the impounding of 65 lorries by the Kenya National and Highways Authority (KeNHA) on Tuesday night.
KenHA impounded the lorries in Matuu for lack of number plates and overloading.
"Last night at around 3am we intercepted 65 trucks without number plates and all carrying excess sand," said KenHA's road asset and corridor management director Njuguna Gatitu.
Mr Gatitu said the authority will charge the transporters with flouting traffic rules and blocking the highway.
"We are asking for reinforcement to have the road unblocked," Mr Gatitu said.
Mr Julius Korir, Infrastructure PS, condemned the sand transporters action, calling it the "the highest form of impunity on our roads."
"The government through the Kenya National Highways Authority in coordination with the Kenya Police is committed to ensuring the road is opened to traffic as soon as possible," said Mr Korir.