The government of Ecuador's Chimborazo province announced the start of the 45.7km Ambato-Riobamba highway widening project.
The event was attended by Chimborazo's governor, Hermuy Calle, and other officials including the transport and public works ministry MTOP's director for Chimborazo, Ingrid Santillán.
Work involves turning the stretch into a 30.5m wide four-lane divided highway with a 3.0m wide median strip, MTOP said.
Construction is estimated to take two and a half years and cost US$227mn.
Santillán said work also involves pedestrian and vehicle bridge construction, return ramp construction and other elements.