The Herrenknecht company specializes in tunnel-boring equipment. Three of its enormous drilling machines tare in Mexico to solve an equally massive problem: the inadequate drainage and wastewater system of Mexico City. The Mexican government is building what will be the world's longest wastewater tunnel, the 62-kilometer Tunél Emisor Oriente .

In part two, the first of three machines is delivered to Mexican authorities at the Herrenknecht factory in Germany; and preparations get underway on site in Mexico City. The new tunnel is set to be completed in 2012. Until then, protective barriers and pumps keep the city above water.