Work is continuing on a section of the Ben Luc - Long Thanh Expressway in southern Vietnam through a mangrove forest. 

The 57.7-kilometer Ben Luc - Long Thanh Expressway between the southern provinces of Long An and Dong Nai and passing through HCMC will be the longest expressway in southern Vietnam. Construction began in 2014 and was scheduled to finish in 2020. But it is still only 80 percent complete with the complex topography, delaying progress, especially the 3.3-kilometer section through a mangrove forest in Long Thanh District in Dong Nai Province, the construction company, Vu Thanh Tra, head of the management board of the expressway section, said. 

The section is part of a five-kilometer component in Nhon Trach and Long Thanh districts in Dong Nai. 

Tra said the work is highly complex because the mangrove forest is regularly flooded by river tides.

"It took us nearly a year to build a service road and the first items in the expressway section. The difficulty lies in also protecting the ecosystem while carrying out the construction." 

The section across the mangrove forest has 77 viaduct piers and is mostly built in semi-submerged areas.

Around one kilometer of girders have been installed through the forest.

The expressway section passing through the area will be 24 meters wide with four lanes and two emergency lanes.

For sections over water, temporary bridges have been built and workers have to use barges to carry machinery and construction materials. On peak days six barges are in use.

The largest bridge in this package crosses the Thi Vai River.

Workers prepare to drive reinforced concrete piles into the Thi Vai River.

Workers building bridge piers in the river work from barges.

Some 100 workers, engineers and experts regularly work on this package, with the figure rising to nearly 1,000 on peak days. 

The expressway begins near Ben Luc District in Long An and runs through the province for five kilometers before linking up with the HCMC - Trung Luong Expressway.

According to the Ministry of Transport, it will help ease traffic on National Highways 1 and 51, reduce traveling time between Long An, HCMC, Dong Nai, and Ba Ria - Vung Tau and serve as a link to Long Thanh International Airport in Dong Nai whose construction began earlier this month. 

To cost around $1.6 billion, the expressway will include a number of bridges adding up to a combined 20 km, with the two major ones being Binh Khanh between HCMC's Nha Be and Can Gio Districts and Phuoc Khanh between Can Gio and Nhon Trach District in Dong Nai. 

Another problem faced by the project is land acquisition due to opposition from residents in both Dong Nai and HCMC.