The accident happened at around 3:15 p.m. on December 9 when the woman was crossing the Hanoi-Lao Cai Expressway, which connects the Vietnamese capital with the mountainous resort town Sa Pa.
A traffic video that was posted online on Monday showed the victim crossing the expressway just before she was struck.
The woman almost reached the divider when she was suddenly hit by a car in a lane that allows a maximum speed of 100 kph. She was thrown in the air and died upon hitting the ground.
According to Vietnam’s traffic regulations, expressways are exclusively for cars. Pedestrians found on expressways can be fined VND100,000-200,000 (US$4.24-8.47).