The 1,000-mile (1,600-kilometer) road, which could stretch as wide as six lanes in some places, is supposed to reduce congestion on the nation's only other north-south thoroughfare, a two-lane coastal route that frequently shuts down due to flooding in the monsoon season.

Government officials hope it will stimulate the country's chronically struggling economy. By linking the north and south, and opening east-west corridors to connect the road to neighboring Cambodia and Laos, the project will "promote the country's internal strength for socioeconomic development," according to the official news agency.

The road is also widely seen as a thumb in the eye of Vietnam's old enemy. During the war the United States tried to bomb the trail into oblivion to end its function of supplying troops, supplies and weapons in support of Hanoi's invasion of the South.

Once the highway is completed, tourism authorities in Hanoi envision package tours built around the trail's bloody history. According to the official news agency, dozens of battlefields along the way are being singled out for tours based on such themes as "Following the Footsteps of the Liberation Army," and "Singing is Louder than Bombing."

FORCED LABOR TIFF

Given the government's enthusiasm, western observers have been surprised by the level of public criticism the project has aroused within the country. The usually docile National Assembly has been a forum for sharp debate. Vietnam Politburo officials have even squabbled among themselves, hurling accusations of chicanery, stupidity, and abuse of power.

One embarrassing episode involved complaints that the government was relying on forced labor to build the road. A human rights group reported to the United Nations in August that Vietnamese between the ages of 18 and 35 were being required to do unpaid work ten days a year on public construction projects. According to the Vietnam Committee for the Protection of Human Rights, this violated the International Covenant on Civil and Political Rights.

The government subsequently announced that road workers not only would be paid, but would be given preferential treatment in the areas of insurance, illness, occupational safety, working hours, wages, and bonuses.

Some of the sharpest criticism has centered on the effects of the project on the country's natural systems, still under assault after 25 years of peace. Five prominent environmental groups, including the Worldwide Fund for Nature, proclaimed in August that the highway poses a serious threat to many endangered species.

During the war, large areas of Vietnam's inland and mangrove forests were lost to pesticides, including Agent Orange, and to bombing and napalming. The degradation has continued during the post-war period as the country has tried to rebuild its economy and production system. As in other tropical regions, forest losses also continue due to the growing demand for firewood and agricultural land to feed growing populations.

FOREST LOSSES CONTINUE

The World Wildlife Fund estimates that Vietnam's forest cover has dropped from 43 percent in 1943 to 19 percent today. Only 4.9 million acres (2 million hectares) of natural primary forests remain, and they are being reduced at a rate of 250,000 acres (100,000 hectares) to 500,000 acres (200,000 hectares) per year.

Environmentalists fear that the new highway will accelerate this destruction by cutting through protected areas, displacing minority populations, and bringing into these remote areas a massive influx of people from the crowded coast.

Among the ten environmentally protected areas the highway will run through or near are Cuc Phuong, the country's first national park in the north, and the Phong Nha nature reserve in the central province of Quang Binh. The Phong Nha reserve, internationally known for its endangered species, has been proposed as a United Nations World Heritage Site.

The government is researching the possible impact on Phong Nha and already has decided to reroute the highway to avoid the Cuc Phuong national park in the north. Other proposals are being considered to elevate the highway in certain sensitive areas - a solution that environmentalists deride, arguing that the routes are likely to be destroyed during construction.

In the meantime, the road moves forward. The government recently announced that engineers from its old ally, Cuba, would be supervising construction of the biggest single section.

A group dispatched from Havana is now working on a key 55-mile (90-kilometer) section in the mountainous central provinces of Quang Binh and Quang Gri. It is the same stretch of trail that Cubans paved in 1973 for North Vietnam's triumphant two-month offensive, which helped end the conflict two years later.

Eye in the Sky is a weekly series that brings you the story behind the headlines using satellite imagery, remote sensing, aerial photography, and maps. This feature is developed by National Geographic News with the sponsorship of the National Imagery and Mapping Agency (NIMA) and Earth-Info. Check out maps and imagery at http://www.earth-info.org.