This piece was originally published in the April 2016 issue of ei, the magazine of the electroindustry.
By Jean M. Johnson, Technical Program Manager/NTCIP Project Manager, NEMA
Temporary traffic situations, including work zones, are a fact of life in the traffic management world. One way to manage temporary traffic situations is with portable traffic signal systems (PTSS).
NEMA TS 5 Portable Traffic Signal Systems, a new standard that will address PTSS, is in development under the auspices of NEMA’s Transportation Management Systems & Associated Control Devices Section.
PTSS commonly facilitate the safe flow of traffic in normal activities, as well as that of atypical congestion related to highway construction or other temporary work zones. PTSS may also be deployed in other circumstances, such as during or after emergencies, for planned events, or to accommodate other signal timing needs that are outside the norm.
When PTSS temporarily replace permanent traffic signals, they minimize bottlenecks and contribute to road safety. The Manual on Uniform Traffic Control Devices (MUTCD) is approved by and incorporated by reference in Federal Highway Administration regulations. As such, the manual is recognized as the national standard for traffic control devices used on all public roads.
According to MUTCD, “…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).”
There are two types of PTSS:
- TR1 PTSS are trailer-mounted and feature a minimum of two signal heads (the assembly containing a red, yellow, and green traffic light) pointing in the same direction, mounted on an overhead mast arm
- TR2 PTSS are either trailer-mounted or otherwise transportable and feature a minimum of one signal head pointed in one direction, without an overhead mast arm
Draft NEMA TS 5 Portable Traffic Signal Systems identifies various characteristics of PTSS that agencies or other users may require:
- Signal timing plan(s) and ability to configure such plan(s)
- Pedestrian indications
- Battery operation
- Pre-timed and manual control provisions
- Actuated movement and related controls
- Event log and data log provisions
- Malfunction management unit capabilities
NEMA TS 5 will standardize a means for users to identify the PTSS features that may be needed for a particular implementation.
Ms. Johnson develops standards on transportation control devices, NTCIP (a family of intelligent transportation systems communications protocols), and airport baggage and passenger security.