Possible
Government/private funding (providing faster trains, e.g. Shalimar Express/launching new services/computerising ticket system)
Allowing private operating companies who pay to use track
Electrification
Changing single track to dual (e.g. Khanewal to Lodhran)
Foreign funding (e.g. Karakoram Express, Lahore to Karachi, launched 2002, mostly funded by China)
Not possible
Hilly/difficult terrain (especially SW Balochistan/high mountains in N/NW) Much of network single line/track
Lack of maintenance over a long period (worn out rails/sleepers) Inefficiently managed (overstaffed/operational inefficiencies/delays/corruption/uneconomic stations)
Outdated locomotives Shortage of rolling stock Lack of funding