Atkins was commissioned by Kenya to design the new facility.
Angama Airstrip is being converted into an international airport.
Project will incorporate a BRT line to ease traffic congestion.
The four-lane dual carriageway is now 99% complete.
Olkaria 1 Unit 6 will inject 83MW into the national grid.
The road begins at Mlolongo, connects JKIA to the CBD, and ends in Westlands.
On completion, it will be the third highest bridge in Africa.
The project has been delayed by land compensation disputes.
The project has a contract sum of $163m (Sh18.7 billion).
The project is co-funded by the Japan Int. Cooperation Agency.