The Mong Sen viaduct on an expressway between Hanoi and Sa Pa will open to traffic this year. The viaduct will cross two hills past a hydroelectric power station and Sa Pa’s rice terraces. It is 612 meters long with five continuous spans, and 14 meters wide with four lanes. Construction started in January 2021 at a cost of VND450 billion (US$19.8 million), and is now 99% complete.