“Transport officials said rails under direct sunshine might reach 20C (68F) above the surrounding air temperature, causing the steel to expand – raising concern that rails will buckle as temperatures soar.” https://www.telegraph.co.uk/news/2018/06/26/uk-weather-railway-slowdown-stop-tracks-buckling-heatwave-set/
Network Rail assured passengers that slowing trains to mitigate this risk was in no way a consequence of going berserk with the chainsaw in the spring and removing all those miles of shady mature tree cover.
“Network Rail admits the vast majority of the trees are healthy. It defended the felling, saying its new tree database of hotspot problem trees has “revolutionised” its approach to “vegetation management” to cut delays and risks to passengers from tree branches.
The company said the average tree had between 10 and 50,000 leaves, any or all of which could fall on the line.” https://www.theguardian.com/business/2018/apr/29/millions-of-trees-at-risk-in-secretive-network-rail-felling-programme
Phase two will see concrete ‘icing’ applied to trackside bankings to stop the unforeseen mass erosion of soil burying lines.