Chinese engineers are racing to complete the the project by June next year.
The project will be completed in two years at a cost of Sh2.3 billion.
The Chinese-built railway began commercial operations on January 1.
Slow approvals of Public Private Partnerships usually puts off high quality investors.
The project is expected to gift Tanzania with its first high-speed railway.
An elevated railway will run 6.7 kilometres across the national park perched on giant pillars.
World Kaihatsu Kogyo is finalising work on phase one of the Ngong Road dualling project.
Nairobi has discarded the Dar es Salaam model that has been found wanting.
The government hopes to launch construction works by August.
AfDB has reportedly declined to disburse the first instalment of the loan.