This translates to 236,700 ha of land, whereas the constmction of the paved 20-metre-w'ide Trans-Mongolian Highw ay takes only about 6,000 ha. Surface water flows are concentrated and accelerated, leading to soil erosion and increased sediment loads in watercourses. Full revegetation of damaged swathes takes 10-15 years after the track has ceased to be in use.