It is almost always the case, that a servient estate holder cannot unilaterally move an easement located on his property.
What if the use of the easement is far smaller than the area provided? For example, suppose an easement was created which was 100 feet wide, but the roadway providing the ingress/egress to the dominant estate holder was only 25 feet wide? What if the placement of the road was such that using the balance of 75 feet was impossible? Since the dominant estate holder’s access could remain the same if the 25 feet was located on a any section of the 100 foot easement, should the servient estate holder be able to shift the road to a different portion of the easement?
There is no clear answer to this question, as Washington State courts have not dealt with this particular issue. They have held that “where a right of way is established by reservation, the land remains the property of the owner of the servient estate and he is entitled to sue it for any purpose that does not interfere with the proper enjoyment of the easement.” Thompson v. Smith, 59 Wn.2d 397, 408 (1962). In Thompson, there existed an road on an easement which only used one half of the easement. The balance of the easement was unused, so the servient estate holder built a concrete slab extending into the easement. This was found to be within his rights as a property owner because the placement of the slab did not ultimately interfere with the use of the easement. This is not the same as having a road and moving it unilaterally, however.
In an analogous case, Crisp v. VanLaecken, 130 Wn.App. 320, 324 (1960), the court held that the servient estate holder could not make “reasonable changes in the location or dimensions of an easement . . . to permit normal use or development of the servient estate.” This held, even thoughthe easement itself would not have been harmed.
There is more precedent which mirrors Crisp, essentially favoring uniformity, stability, and predictability in property rights. So, even though there is not a case on point as to whether a road within an easement can be shifted, courts in Washington like to err on the side of stability/predictability in property rights. It is almost as though the road within an easement is another easement within an easement.