The Railway Investment Prioritisation Strategy could see the first major multi-million pound investment programme in the railway network since the closure of lines in the 1960s.Depending on funding the proposal could see new track relays on the Coleraine to Londonderry line, improvements to the aging Enterprise service and stations and halts upgraded.The document also includes the potential for a railway line that could connect Belfast International Airport to the network.However, for it to be viable, the report says passenger numbers at the airport would need to increase significantly from the current 4m to 10m.In the past decade railway passenger numbers have increased from 6m to 13m and the railways strategy publication comes after an extensive public consultation on services.UUP Minister Kennedy said: "This ambitious strategy allows for a significant enhancement of existing rail capacity, preparation for the future electrification of the network and the first major extensions to the railway since the closing of lines in 1963."I am particularly keen to extend the option of rail travel to commuters from mid-Ulster and to the populations in the south and west within the catchments of Armagh and Dungannon."Although the speed of progress will depend on the amount of funding that can be made available from the Executive's budget and, where possible, from the European Programmes, I am committed to exploring all funding opportunities and making this happen."It's estimated that the service will require £620m to maintain the current network and rolling stock over the next 20 years.Minister Kennedy added: "It will be important, in the present period of public expenditure restraint to use available resources to sustain and make best use of the current railway system and to develop it where there is the greatest potential for further passenger growth."I believe rail travel offers a safe, comfortable and efficient option, particularly for commuters and inter-city passengers."As and when additional resources become available, we must be ready to develop our rail network and this strategy sets out how we can make that happen."