The tunnel forms part of the 120km Phase 2A of the SGR linking Mombasa and Nairobi with the Ugandan border being constructed by China Road and Bridge Corporation.
Construction of the second phase, which will run from Nairobi to Naivasha, was officially launched by President Uhuru Kenyatta in October 2016.
The 472km first phase from Mombasa to Nairobi open in May 2017.
