Blea Moor Tunnel in the Yorkshire Dales will be fitted with ice prevention covers to prevent an event similar to 2010 derailment when a train riding at 70mph hit a huge block of ice. Although regular checks were introduced after the event, experts are worried about "ice chandeliers" forming in winter.

Problem is; when this tunnel was built in late 19th century, it was built with 3 shafts. Rain is said to leak into the tunnel from these shafts and help form ice on the track as well as on the ceiling of the tunnel. In the case of 2010 accident, the ice formed on the tracks was big enough to derail a speeding train.

Finally some preventive measures will be taken.

http://www.richmondshiretoday.co.uk/action-to-avert-repeat-of-tunnel-incident-on-settle-to-carlisle-line/