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Construction at high altitude, in mountainous terrain, presents significant challenges to adequately address requirements for erosion/sediment control and revegetation. Long uninterrupted steep slopes constructed from rocky and highly erosive mountain soils at high altitudes are subjected to significant solar radiation. Combined with extreme heat and seasonally arid conditions, punctuated by brief but intense rainy periods, these conditions present significant challenges to designers, contractors and materials alike.

In 1996 the Caminos y Puentes Federales, the Mexican equivalent to the U.S. Federal Highway Administration, initiated a project to improve the Autopista (Mexico Highway 131) in the State of Oaxaca. The Autopista runs north from the City of Oaxaca approximately 250 kilometers to intersect with Mexico Highway 150, which connects this state capital of 600,000 population and burgeoning tourist destination to the national capital, Mexico City. As the roadway winds its way northward through mountainous terrain from Oaxaca, the Autopista reaches an elevation of approximately 3,240 mete rs above sea level.

This paper discusses the process and design-build approach that was utilized to select and prescribe the most appropriate erosion control materials and revegetation techniques that led to the successful implementation of the project by the contractor, Corporation Nacional de Construcciones SA de CV, a major Mexican highway construction company. The 6 km long project included fill slopes constructed at 2H:1V with slope lengths that exceeded 67 m. The total area of critical slopes totaled approximately 58,300 m(2).

The lessons learned on this project can provide meaningful guidance in meeting similar challenges with proven, cost effective, Best Management Practices that have widespread application.