Infrastructure Principal Secretary Engineer John Mosonik says those who fail or ignore to vacate will not be spared from demolition or face prosecution.
He said the ministry plans to ensure that all road reserve boundaries are clearly marked to deter future encroachment.
Some of the semi-permanent structures which are on the increase along the roads include shops, storage facilities, parking lots, car bazaars and car washes.
“These structures are hindering proper drainage of storm waters and therefore causing severe damage to roads,” the PS told journalists on Thursday.
He lamented that the menace has not only made it hard to guarantee road maintenance but also undermined efforts to improve road safety especially for pedestrians.
“In upper Eastern, over 200 illegal billboards, farming activities and several temporary structures have been noted. Fifteen and 35 spots containing temporary illegal structures where encroachers are edging towards permanent construction have been noted in North Eastern and North Rift valley respectively,” Mosonik said.
The ministry have also raised alarm over the increase of road furniture especially metallic road signage and guardrails which he said are mostly sold to scrap metal dealers.
“This is depriving roads of critical warning signs and safety facilities and is significantly contributing to road accidents, besides the high cost of maintenance,” he complained.
He mentioned that the ministry is spending on average Sh1.2million per month for patrol and maintenance on Mombasa Road alone after all the guard rails separating carriageways between Miritini and Mazeras were vandalised.
Thika Superhighway, Kisumu Busia highway and the Meru Isiolo roads, he said, have not been spared from the menace.
Going forward, the ministry now plans to hasten the public private partnership to enhance not only maintenance but management and operations of toll stations.
“In the next one year, we are planning to start with Thika Superhighway and the Nairobi Southern by-pass. To address capacity constraints, the ministry is collaborating with institutions of high learning and other development partners to train more engineers.”