Methodologies

Portable signal methodologies do vary. One of the common methodologies is to have the intelligence distributed. This might mean that within each node or portable signal device timing and monitoring is done locally. The timing is sometimes done completely with precision time clock(s) that are redundant of necessity. This system precludes the use of detection or preemption unless a means of communication between trailers is included. Some specifications under this and its variations specify identical control systems for each node. This is contrary to the established standards for permanent traffic signals, where most of the control and monitoring is centralized at a master location. This type of technology may be more difficult to defend against tort claims, as it lacks the pedigree and the testing procedures of the established monitoring standards. Third party automated testers currently handle the testing of monitors within the established standards, which provides a disinterested party to verify the proper functioning of the monitor on a regular basis, which can be critical in the event of a tort claim.

Hardwire connections between portable signals nodes are largely for those users/buyers that aren’t confident with radio system qualities. Hardwire doesn’t make a lot of sense otherwise. The weakness of hardwire is that it typically requires running the cable across a roadway and often through a construction area. The beauty of radio-connected systems is that they are fast to deploy.

Radio systems have come a long way from early attempts to use “off the shelf” systems. Now we at OMJC integrate a radio right into the system hardware and software design. Our most recent radio system can be interrogated and modified on the fly. One can view definitive RSSI, response times, and communication error data, enabling real time adjustments that can be made while the system is operational. This qualitative data is very useful for tweaking in a system to ensure stability for long duration deployments, or to compensate for topography that is “pushing” the system, such as mountain areas.

As for current offerings in conflict monitoring, OMJC presently offers a system (our 2070/ATC) that operates with high end real time ITS monitoring and handles it through an integrated spread spectrum radio system that emulates a NEMA TS2 BIU/MMU arrangement, enabling wireless operation between non-connected portable signal trailers. Today we are utilizing equipment much like you would see in the normal traffic signal cabinet, able to monitor hard and soft failures and even current levels on each monitor channel. Modern traffic phasing and deployments go from simple to complex, and modern portable signals such as our 2070/ATC system, with fully actuated eight phase intersection capabilities, are now up to the task.

Become an Informed Buyer

We would encourage buying agencies to understand what they are buying. The industry is divergent enough that without agencies specifying standards there could be a smorgasbord of types of equipment one could procure. When purchasing portable signals, some basic questions that need to be asked include:

1.) Who will be using the equipment?

2.) Who will set up the equipment?

3.) Who will provide the controller timing?

4.) What is the frequency that the equipment will be used?

5.) How long are the durations of typical uses?

6.) Will the system need to have vehicular or pedestrian detection?

7.) How complex will the traffic phasing be?

8.) How much versatility does the owner want?

9.) Is shading or overcast skies a common occurrence where the equipment will be used, thereby diminishing the effectiveness of solar power?

10.) How long do you want the system to run on battery power alone?

11.) Is the application to replace permanent signals during construction?

12.) What is the capacity of the user to maintain the equipment?

13.) Do the system nodes also need to be able to function merely as a portable mast arm in the event of an emergency knock-down, with the ability to pass control of the on-board signal lights to an existing signal system?

14.) What is the size of the footprint available for the equipment to be positioned? Trailer widths vary from 6 to 8 feet.

15.) What level of training will operators need?

16.) Are you comfortable that the level of system monitoring offered will give you adequate tort protection?

Buyers need to know that features and quality come with a price. Three big factors that control competitive costs are: overall system power consumption, the features required, and the quality required.