In some counties this is grant aided by the local councils.
If there is more than one user of the road, (does not have to be to a house, just a farm), the users pay maybe 10% and the rest is grant aided by the council.
The scheme is called the LIS (local Initiative Scheme). They are very common in some rural counties such as Donegal, and very successful.
Usually one person has to take the lead, getting the forms out and having them filled in by all users if they wish to participate. Not everyone using the lane/road has to sign and agree, but it is cheaper obviously on everybody as the initial 10% or whatever is required is split on more users.
Contact you council, and find out the procedure for their patch.