29 March 2017
Nepal rural roads: the hazards of construction without design
One of the major themes that I return to regularly is the problem of Nepal rural roads, and the landslides associated with them. Regular readers will know that I have an intense interest in landslides in Nepal, one of the true global hotspots for landslide problems. My interest in Nepal started way back in 2000 when I was involved in a research project that sought to find better ways to select the routes for rural roads to reduce landslide hazards. That project was led by Dr Gareth Hearn, then of Scott Wilson but now working for Hearn Geoserve, who is in many ways the guru of rural road design in high mountain areas. Gareth is also the best geomorphological mapper I have ever met, as well as a highly talented engineering geologist. He has written numerous publications about the assessment of terrain in steep mountain areas, and is the author of various guidelines about rural road building.
In a paper just published in the Quarterly Journal of Engineering Geology with N.M. Shakya from the Department of Roads in Nepal (Hearn and Shakya 2017), Gareth has examined problems of rural road construction in Nepal and India once more. The paper notes that there are numerous guidelines for proper road construction, and that the underlying techniques are well established. In the paper, they highlight a World Bank report from 2013 that notes that:
…it was stated that over half of the local road network is untraffickable owing to non-engineered road construction, with roads becoming impassable within 1 – 2 years after completion. If this estimate is true, there may be of the order of 30,000 km of roads constructed in the country that have little hope of sustainability without significant remedial investment and that are having, by all accounts, severe impacts on slopes and drainage systems.
Hearn and Shakya (2017) suggests a number of key issues that need to be addressed:
- Proper route selection is needed. They note that: “there is rarely such a thing as the perfect alignment because compromises often have to be made between the desire to avoid crossing difficult and geohazard-prone terrain and environmentally sensitive areas, and the need to minimize route length and construction cost. It is usually necessary to identify those areas that pose the greatest difficulty and highest risk, and avoid them where possible.”
- Construction must be appropriate, using design that is carefully considered around management of water, support of cut slopes and the emplacement of fill.
- Careful consideration of the hazards posed to road users and people living along the road corridor.
The frustration of course is that none of this is new. As Hearn and Shakya (2017) point out:
Sustainable engineering for the future development of infrastructure in the Himalayas is entirely achievable as long as a carefully planned, managed and executed, inclusive approach is applied. This approach must make full use of the experience and professional knowledge embodied in the available guidelines and specifications, take full cognisance of the geological and geomorphological fragility and dynamism of the region, and learn from the successes and failures of the past.
This paper is both wise and perceptive. It really is time to start constructing Nepal Rural Roads properly.
and Engineering challenges for sustainable road access in the Himalayas Quarterly Journal of Engineering Geology and Hydrogeology, doi:10.1144/qjegh2016-109