▁have ▁seen ▁a ▁major ▁rev amp ▁of ▁the ▁service ▁pattern ▁in ▁operation . ▁ ▁The ▁work ▁however ▁fell ▁well ▁behind ▁schedule , ▁with ▁Network ▁Rail ▁adm itting ▁in ▁January ▁ 2 0 1 8 ▁that ▁the ▁work ▁would ▁not ▁even ▁be ▁completed ▁in ▁time ▁for ▁the ▁next ▁tim et able ▁change ▁in ▁May . ▁ ▁This ▁was ▁due ▁to ▁unexpected ▁problems ▁with ▁poor ▁ground ▁conditions ▁in ▁several ▁locations , ▁which ▁meant ▁that ▁some ▁ 2 0 0 ▁m asts ▁for ▁the ▁overhead ▁w ires ▁could ▁not ▁be ▁installed ▁as ▁planned . ▁ ▁In ▁order ▁to ▁complete ▁the ▁remaining ▁work ▁by ▁the ▁end ▁of ▁the ▁year ▁( both ▁p iling ▁for ▁the ▁m asts ▁and ▁the ▁actual ▁w iring ), ▁further ▁week end ▁block ades ▁were ▁im posed ▁by ▁Network ▁Rail , ▁which ▁were ▁expected ▁to ▁continue ▁until ▁November ▁ 2 0 1 8 ▁( al ong ▁with ▁a ▁nine - day ▁line ▁closure ▁in ▁late ▁August ). ▁The ▁planned ▁tim et able ▁rev amp ▁( including ▁the ▁return ▁of ▁Glasgow ▁and ▁Edinburgh ▁trains ▁and ▁through ▁services ▁to ▁south ▁Manchester ▁and ▁Ch esh ire ) ▁have ▁also ▁had ▁to ▁be ▁post pon ed ▁until ▁May ▁ 2 0 1 9 ▁as ▁many ▁of ▁these ▁improvements ▁were ▁dependent ▁on ▁the ▁avail ability ▁of ▁electric ▁rolling ▁stock . ▁ ▁The ▁first ▁over night ▁electric ▁test ▁trains ▁ran ▁successfully ▁in ▁December ▁ 2 0 1 8 . ▁Electric ▁service ▁comm enced ▁on ▁ 1 1 ▁February ▁ 2 0 1 9 ▁util ising ▁Class ▁ 3 1