Introduction: Fencing along a highway is a means of preventing unwanted and likely intrusion of animals@ people@ vehicles@ machines@ etc.@ from outside the right-of-way line or access control line into the vicinity of moving traffic or onto the operating right-of-way. This applies to both full or partial controlled facilities. The fencing along highways has generally grown from an adjacent owner responsibility to that of the highway agency. This change has occurred for many reasons@ primarily for control of animal movement@ pedestrian movement@ and vehicle encroachment--ail to maintain a safe environment for the highway user. One might say@ rather than protection of the adjacent land and property@ it is now the responsibility of the highway agency to provide protection for the motorist. This would be true for the urban area as well as the rural area. Even though some states have open range areas@ the highway agency should work cooperatively with adjacent owners to facilitate safety concerns and the erection of access control facilities. Controlled access highway operation@ wherein drivers move at high speeds with expectation of protection from all forms of roadside interference@ makes fencing the responsibility of the highway agency. Fencing should be provided wherever there is potential encroachment. All portions of a controlled access highway should be continuously fenced unless it can be established that a fence is not warranted; such as in areas of precipitous slopes or natural barriers. Wherever the safety of highway operation requires fencing@ it should be considered as an essential part of the total highway facility@ constructed as a highway item.