They are the vehicles transporting goods to wait for the customs clearance to China.

Hundreds of vehicles have remained stranded at the northern province of Lang Son’s border gates with China
Among those, 251 vehicles are waiting at Huu Nghi Border Gates, including 245 vehicles carrying fruits, while the number at Bao Nguyen, Tan Thanh and Chi Ma border gates are 137, 13 and 2 respectively.
This means that drivers and their assistants have to stay at the border gates during the Lunar New Year’s Eve.
All fresh goods and some other kinds of farm produce are expected to be exported to China through Lang Son border gates during Tet.
Lang Son has offered gifts to many drivers stranded at Tan Thanh Border gates. Each driver was given a gift worth VND500,000, including sweets and drinks.
Le Van Thang, head of Dong Dang-Lang Son Economic Zone Management Board said that local authorities will make concerted efforts to help speed up the customs clearance of goods in the coming time.