Increasing road resilience
Assessing the impact of ground movement on road surfaces in Lincolnshire
Analyses of south Lincolnshire roads reveal a strong correlation between road vulnerability and underlying geology
Roads in the Fenlands area of south Lincolnshire are of national importance, providing vital transport routes for the transfer of agricultural products to the rest of the UK, and beyond. As well as linking producers to markets, the roads provide critical transport links for the local economy and community. However, Lincolnshire roads, particularly in the south of the county, are highly susceptible to ground movement and damage, with vulnerability expected to increase under more extreme climatic conditions.
In a collaboration between the British Geological Survey and Lincolnshire County Council, Anna May Harrison and colleagues analyse compressibility and clay shrink–swell datasets for the subsurface, together with assessments of residual life and visual inspections of deterioration (longitudinal cracks, ruts, edge failure and undulations) for southern Lincolnshire roads.
Their analyses reveal a strong correlation between road vulnerability and underlying geology – specifically the presence of superficial deposits such as peat, tidal flat deposits, and alluvium, which are highly susceptible to compression when loaded – or due to loss of water content because of drought or groundwater lowering through managed drainage and irrigation. These issues are compounded by many of the roads of south Lincolnshire being ‘rural evolved roads’ with shallow foundations, originating essentially from old mud tracks, hence increasing their vulnerability to ground movement.
Historic road repair strategies have, in some cases, compounded the road settlement issues. Revised approaches to maintenance and repair work (based around material recycling and reinforcement techniques) instigated by Lincolnshire County Council are now helping to extend road life. Future monitoring (including via remote sensing) and regular condition surveys will establish the precise efficacy of new repair techniques, and the resilience of the transport network to climate change.
The study highlights that improved understanding of the relationships between the geological, climatic, and anthropogenic driving forces on ground movement and road damage facilitates a more informed prioritisation of repairs and improved site-specific road repair practices, thereby increasing future resilience. The authors consider their findings, relevant to other parts of the world with similar land use and geological properties – notably reclaimed land and river flood plains.
The research is published as part of a thematic collection entitled Climate Change and Resilience in Engineering Geology and Hydrogeology available at: www.lyellcollection.org
Colin Serridge
Details
Q. J. Eng. Geol. Hydrogeol. 56(3), 2023; doi.org/10.1144/qjegh2023-002
