How Many Dwelling Can Be Erected On Land Locked Property?

The fact that the property is landlocked doesn't really matter with regard to the number of dwellings that are permitted. It depends on how the property is zoned. You would have to contact the zoning department in town hall. They should be able to tell you the number of dwellings permitted in that area.

Once you find out how many dwellings are allowed you would first have to try and reach an agreement with one of the neighboring property owners for an easement to cross their property to access the road. The easement would have to apply to all of the dwellings that would eventually be constructed. If none of the neighbors are willing to reach an agreement then you would have to file a motion in court to get an easement declared by necessity. The court might limit the number of people who could use the easement based on a "reasonableness" test.

If you are seriously considering developing landlocked property then I suggest that you speak to a land use attorney before you start making any plans.