Question to the Department for Transport:

To ask the Secretary of State for Transport, whether her Department is supporting research into Soil Moisture Deficit forecasting and monitoring technologies.

High soil moisture deficit levels within earthworks arise when the earth has become dried out following prolonged dry hot weather, leading to the soil shrinking and cracks developing within. If this is followed by a period of extreme or prolonged rainfall, water entering these cracks can lead to rapid failure of the earthworks.

Network Rail has commissioned an active nationwide monitoring regime using remote sensors, modelling and geotechnical assessments to monitor slope stability across the network. It has also supported academic research, such as the ACHILLES programme, to further industry understanding on the loss of material strength from repeated cycles of wetting and drying. Intelligence from such research is fed into strategic whole life costing modelling to inform future renewal and maintenance activities. At the same time, Network Rail is engaging in proactive measures to reinforce embankments in high-risk areas and reduce water retention and erosion.

Together, these measures should reduce the risk of earthworks failure and improve the long-term resilience of these assets despite the increasing number of extreme weather events that are expected due to climate change.

I am aware that this issue has been particularly problematic on the West of England Line. I am assured by Network Rail that conditions are improving and that it plans to restore a full timetable from 29th November.