Hearn G.J.,Hearn Geoserve Ltd |
Shakya N.M.,Ministry of Physical Infrastructure and Transport
Quarterly Journal of Engineering Geology and Hydrogeology | Year: 2017
Improved road access is fundamental to the current drive for economic development and livelihood improvement in many parts of the Himalayas. There is a history of over one hundred years of road building in the region and an expanding road network that faces serious challenges to its sustainability. These challenges include severe terrain, dynamic geology and heavy rainfall, with earthquakes, landslides, floods, erosion and sediment posing significant hazards. In both India and Nepal there is a large body of published literature that describes the impact of these hazards on roads, and there are a number of manuals, guidelines and standards for sustainable road construction and maintenance. There is also a strong presence of geological and geohazard expertise in both countries that is able to inform decision-making in route selection and road design. However, it is apparent that this expertise is not always being used and that road construction is sometimes taking place without reference to the established manuals and guidelines. Although the guidelines themselves require consolidating and strengthening in certain areas, including a greater infusion of engineering geology, it is paramount that they are used. The future poses major challenges for the engineering sustainability of road access in the Himalayas, but these can be addressed through careful planning, thorough investigation, adherence to best practice, control of construction practices and learning the lessons of the past. © 2017 The Author(s).
Hart A.B.,URS Infrastructure and Environment UK Ltd formerly Scott Wilson Ltd |
Hearn G.J.,URS Infrastructure and Environment UK Ltd formerly Scott Wilson Ltd |
Hearn G.J.,Hearn Geoserve Ltd
Bulletin of Engineering Geology and the Environment | Year: 2013
The Paphos District has been described as one of the most landslide-prone areas of Cyprus, with landslides impacting villages, roads and other infrastructure. With increasing levels of development and investment in infrastructure, Cypriot authorities are investigating ways to assess landslide susceptibility, hazard and risk for planning purposes. A 2-year project has catalogued over 1,840 landslides, investigated the spatial distribution of key landslide attributes, and used the results to develop maps of landslide susceptibility across large areas of the Paphos District. To gain a better understanding of the materials and failure mechanisms involved, 20 of these landslides were selected for further study, including engineering geological mapping, ground investigation, laboratory testing, development of ground models and slope stability analysis at specific locations. The results enabled soil parameters to be reviewed, thus strengthening the interpretations derived from field observations. The use of the mapping outputs is discussed in terms of planning and engineering applications and recommendations are made for strengthening and expanding the landslide database. © 2013 Springer-Verlag Berlin Heidelberg.
Hearn G.J.,Hearn Geoserve Ltd |
Pettifer G.S.,83 Langdale Avenue
Bulletin of Engineering Geology and the Environment | Year: 2016
The role of engineering geology in the final design and construction of a road crossing the Blue Nile (Abay) gorge in Ethiopia is described. This new road between Mekhane Selam and Gundewein is a strategic link in the Ethiopian road network and encounters very steep and difficult terrain that poses significant engineering geological challenges. Remote sensing, landscape modelling, reference condition classification, and conventional field mapping have been applied to assist in the finalisation of the alignment, the prediction of ground conditions for earthworks design, and the implementation of slope and drainage protection works. The approach adopted serves as a blueprint for other road construction and improvement projects in the region though limitations exist with respect to the prediction of variable volcanic rock sequences at depth without the benefit of ground investigation boreholes. Although ground conditions different from those predicted have been exposed along 15 % of the alignment, these have been of relatively minor significance and have necessitated unanticipated remedial action affecting less than 2 % of the alignment in the gorge. Thus far, the main damage to the road from geohazards has been caused by road-related effects, including the concentration of road drainage below culverts and seepages from broken and blocked side drains. The susceptibility of the terrain to uncontrolled runoff is such that preventative and reactive maintenance will be required throughout the lifetime of the road. © 2015, Springer-Verlag Berlin Heidelberg.
Hearn G.J.,Hearn Geoserve Ltd
Bulletin of Engineering Geology and the Environment | Year: 2015
Calcretes have been used extensively in southern Africa, and elsewhere, for low-volume road construction. In Inhambane province of Mozambique, naturally occurring gravels are rare and calcrete is used wherever it is known to occur in reasonable proximity to the road network. While considerable research and development has been undertaken in Botswana, Namibia, and South Africa on the prospecting and engineering usage of calcrete, little work has been undertaken in Mozambique. Remote sensing and field probing, followed by trial pitting and laboratory testing were undertaken in order to locate hitherto unknown deposits of calcrete and to test its basic engineering properties for use in road construction. The findings from other parts of southern Africa were examined in terms of their applicability to Inhambane province, and the locations of existing calcrete borrow pits were examined to determine whether they had common geographical attributes that could assist in the identification of new sources. The study led to the discovery of approximately 20 locations of calcrete potential. Thirteen of these were investigated using trial pits, and ten of these yielded calcrete. A list of additional sites within the vicinity of the road network was developed from remote sensing. The occurrence of calcrete appears to be quite localised within the province and its location is governed by very subtle changes in topography and drainage regime, some of which may be inherited from past climate and environmental factors that are no longer apparent. © 2014, Springer-Verlag Berlin Heidelberg.
Hearn G.,Hearn Geoserve Ltd
Proceedings of the Institution of Civil Engineers: Municipal Engineer | Year: 2016
Natural hazards of river flooding, erosion, landslides and high sediment loads in streams and rivers continue to pose a significant threat to the management of infrastructure, particularly road transport, in most parts of the world. In Asia and Africa, especially, these hazards are considered to be on the increase in response to climate and land userelated factors. Recent studies in Africa and especially Ethiopia lead to the conclusion that complex and poorly understood interactions between geology, climate change and land use change have given rise to increased levels of damage and disruption to transport infrastructure. The prognosis for the future is that these trends will continue and perhaps accelerate. Current policies tend to focus on the ‘proofing’ of infrastructure against future climate change, possibly without due regard to other factors that may be more important in the short–medium term. This is possibly counterproductive in situations where existing and future risks are determined more by geohazard uncertainty and design deficiencies, and the sometimes overriding effects of land use change and land management practices. © 2015, ICE Publishing: All rights reserved.