Severe runoff and water erosion can occur from road sideslopes. To investigate the magnitude of runoff and soil loss from road embankment and the effectiveness of a range of engineering and non-engineering erosion control measures, runoff and soil loss were measured along the Qinghai-Tibet highway near Tuotuo river in the summers of 2003 and 2004. The site is characterized by its high altitude, low summer rainfall and permanently poor vegetation cover. The results show that engineering measures can be effective in the short term, while re-vegetation of the road sideslopes is effective when the vegetation cover is established. A combination of lattice and re-vegetation is most effective overall.

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Road network is a critical component of public infrastructure, and the supporting system of social and economic development. Based on a modified kernel density estimate (KDE) algorithm, this study evaluated the road service capacity provided by a road network composed of multi-level roads (i.e. national, provincial, county and rural roads), by taking account of the differences of effect extent and intensity for roads of different levels. Summarized at town scale, the population burden and the annual rural economic income of unit road service capacity were used as the surrogates of social and economic demands for road service. This method was applied to the road network of the Three Parallel River Region, the northwestern Yunnan Province, China to evaluate the development of road network in this region. In results, the total road length of this region in 2005 was 3.70 × 10 4 km, and the length ratio between national, provincial, county and rural roads was 1∶2∶8∶47. From 1989 to 2005, the regional road service capacity increased by 13.1%, of which the contributions from the national, provincial, county and rural roads were 11.1%, 19.4%, 22.6%, and 67.8%, respectively, revealing the effect of ′All Village Accessible′ policy of road development in the mountainous regions in the last decade. The spatial patterns of population burden and economic requirement of unit road service suggested that the areas farther away from the national and provincial roads have higher road development priority (RDP). Based on the modified KDE model and the framework of RDP evaluation, this study provided a useful approach for developing an optimal plan of road development at regional scale.

Understanding the use of small bridges and culverts by wildlife to cross the Qinghai–Tibet railway will aid in the design of wildlife crossing structures for similar transportation infrastructure. From 2014 to 2016, 36 infrared cameras were placed inside 14 small bridges and 11 culverts along the Qinghai–Tibet railway to determine the structures’ effectiveness as wildlife passages. Thirteen species of mammals were found to use the small bridges and culverts to cross the railway. The crossing rates for all mammals were significantly higher for small bridges than for culverts. Tibetan antelope (Pantholops hodgsonii), Tibetan gazelle (Procapra picticaudata), kiang (Equus kiang), and wild yak (Bos mutus) preferred small bridges over culverts to cross the railway. In contrast, mountain weasel (Mustela altaica) and Asian badger (Meles leucurus) preferred culverts to cross the railway. The crossing rates of all mammals, particularly Tibetan gazelle and woolly hare, were positively influenced by structure width. Structure height had a positive influence on wild yak, but structure length had a negative influence on kiang. The distance to the highway had a positive influence on the crossing rates of all mammals, particularly wild yak and woolly hare. Human use of the structures had no influence on the crossings of most mammals except for common wolf. We suggest that road design schemes include large and open crossing structures to benefit most species with limitations on human activities near wildlife passages.

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