25 CFR §169.127

1. (a)If you are the grantee, you may use all or a portion of an existing right-of-way for a use not specified in the original grant of the existing right-of-way only if it is within the same scope of the use specified in the original grant of the existing right-of-way.
   1. (1)If you propose to use all or a portion of an existing right-of-way for a use not specified in the original grant of the existing right-of-way and not within the same scope of the use specified in the original grant of the existing right-of-way, and the new use will not require any ground disturbance, you must request an amendment to the existing right-of-way grant.
   2. (2)If you propose to use all or a portion of an existing right-of-way for a use not specified in the original grant of the existing right-of-way and not within the same scope of the use specified in the original grant of the existing right-of-way, and the new use requires ground disturbance, you must request a new right-of-way.
2. (b)If you are not the grantee:
   1. (1)You may use all or a portion of an existing right-of-way for a use specified in the original grant of the existing right-of-way or a use within the same scope of the use specified in the original grant of the existing right-of-way if the grantee obtains an assignment to authorize the new user; or
   2. (2)You may use all or a portion of an existing right-of-way for a use not specified in the original grant of the existing right-of-way and not within the same scope of use specified in the original grant of the existing right-of-way if you request a new right-of-way within or overlapping the existing right-of-way for the new use.
3. (c)An example of a use within the same scope is a right-of-way for underground telephone line being used for an underground fiber optic line, and an example of a use that is not within the same scope is a right-of-way for a pipeline being used for a road or railroad.