The National Treasury has announced it has begun evaluating bids for a company that will help implement the planned expansion of the 460-kilometre Nairobi-Mombasa highway.

The consulting company will help assess traffic, engineering needs, environmental and social impacts, and costs to determine whether the highway expansion is technically and economically viable.

The multi-billion-shilling project will involve expanding the existing 461-kilometre Nairobi-Mombasa highway from two lanes to at least four lanes, with controlled entry and exit points and toll fees for motorists.

“For the Nairobi-Mombasa Expressway, A fresh Transaction Advisor-Expression of Interest was published on August 11, 2026 and closed before the end of Q1. The evaluation of the bids is underway,” Treasury revealed.

“The project scope comprises expanding it to a minimum of 4 lanes and converting it into a tolled road, while incorporating cost-effective designs to minimise impact on local connectivity,” it added.

In its status update report, Treasury said the expanded road will form part of the Trans-African Highway connecting two of Kenya’s largest cities and, by extension, Central and Eastern African countries.

“The road section is therefore of major economic importance as it promotes trade and tourism through transportation of goods, merchandise and people,” the report stated.

The latest update comes after the government shifted away from a proposal by U.S. infrastructure firm Everstrong Capital to build an entirely new expressway linking Nairobi and Mombasa.

In 2024, Everstrong Capital submitted a 2500 page proposal to build a new six-lane expressway measuring about 440 kilometres at an estimated cost of Ksh365 billion.

The company submitted the plan, but the National Treasury's Public Private Partnership (PPP) Committee rejected the proposal after finding that it did not meet the requirements set out under the PPP Act, 2021.

In April 2026, Everstrong said it was disappointed with the decision and indicated that it intended to challenge the ruling in the High Court.

"We express our disappointment with the decision of the petitions committee declining to uphold a petition concerning the evaluation of the feasibility report for the Usahihi Nairobi-Mombasa Expressway Project," the company said in a statement.

With the latest changes, the government has now listed the project as a priority under the Medium-Term Plan and will be developed through a PPP arrangement.

Once completed, the expanded Nairobi-Mombasa highway is expected to significantly ease congestion along one of Kenya's busiest transport routes.