NEMA TS 5-2017 covers traffic signaling equipment used to facilitate and expedite the safe movement of vehicular traffic and the work that goes on in the respective work zone. Portable Traffic Signal Systems (PTSS) are commonly used to supersede flagger use during roadway construction. While PTSS are used most commonly for single-lane road closures@ PTSS are also used during or after times of emergencies@ planned events@ and non-normative vehicular signalization needs. PTSS are also used before or while permanent signals are being installed to lessen traffic bottlenecks and improve intersection safety during these transition times. PTSS are designed to enable critical movement of traffic using the implementation of appropriate new and existing standards. Manual on Uniform Traffic Control Devices (MUTCD) Section 6F.01 states: All traffic control devices used for construction@ maintenance@ utility@ or incident management operations on a street@ highway@ or private road open to public travel (see definition in Section 1A.13) shall comply with the applicable provisions of this Manual. In addition@ PTSS address many of the factors related to the design and application of temporary traffic control systems and provide much of the functionality@ described in MUTCD 6F.84(08). Also see an FHWA Official Interpretation concerning ??Conflict Monitoring of Temporary and Portable Signals?? in Annex A.