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Many work zone devices, such as truck-mounted attenuators, cones, and barrels, are used to separate workers from the traveling public during construction and maintenance activities. However, these devices do not provide lateral impact protection. Conversely, concrete barriers are often used to physically separate workers and moving traffic at long-term construction projects. Unfortunately, many work activities are of shorter duration or require continuous movement along the roadway, and so cannot be protected through concrete barrier placements. This paper describes a set of functional requirements developed for highly-portable positive protection technologies that protect highway workers. These requirements were based on an assessment of a large number of construction and maintenance work activities that are highly mobile and thus would potentially benefit from such a system. Specific roadway design features believed to have the most significant impact upon the functional requirements of a highly-portable positive protection system were also considered. While it is desirable to have a protective device that covers a wide possibility of work zone conditions, this preliminary study shows there are some practical limits to activities that ca