Tech Tip
by Jack Mason, PTE

NWSVoyage™ FYLTA/Pedestrian Safety Module

This module was developed on contract with Oregon DOT and is to be added to the NWSVoyage™ 2070 program. The problem which is addressed has been of increasing concern to government and consulting traffic engineers and signal timers. Responding to ever increasing traffic demands a Flashing Yellow Left Turn Arrow (FYLTA) display was developed to provide a permissive period for left turns. This created a new conflict with pedestrians who are crossing the adjacent street in the crosswalk that the left turners go across. On high speed, 5-lane roadways the conversion from a protected left turn to a protected/permissive left turn has created unsafe maneuvers where the left turning vehicle doesn’t see the pedestrian, who is legally crossing in the crosswalk. We present this module as a graduated means to lessen the left turn & pedestrian conflict.

In general, regarding FYLTA operation it is good to think of it as 4 phase-pairs where the even phase is the through movement and the odd phase is the left turn. All of the various controller data entries  work on only one central problem: Relative to the start of the even phase green, when shall the FYLTA be displayed?

FYLTA/Ped Modes:

This module primarily addresses the common condition where the main street is Green and its left turn signals are in FYLTA. A pedestrian then arrives and pushes the button to cross the side street, in parallel with the main street. Currently, if the intersection is in Free or if it is in coordination and the ped permissive is open, the Walk will come up immediately with no change to the vehicle signals. With this new module there is a very significant change for the pedestrian. Pedestrians will have increased safety and also increased delay. They won’t get their Walk until one or both of the main street phases are terminated with a Yellow & Red and then come back to Green with a Walk but no FYLTA.
The following matrix shows the two major elements of this module.
1. How will the even phase of the pair be cleared?
2. What level of protection will the pedestrian receive?

Behavior Matrix for the mode of FYLTA/Ped Operation:

Note: To comply with MUTCD a 3 second buffer is incorporated into modes 2 & 4. This buffer will delay the start of the FYLTA after the end of FDW.

A more detailed description of modes 1 to 4 is below.

Mode 1: If an Even Phase Pedestrian Call is serviceable and the FYA is not active, the FYA will be delayed until the WALK is completed. If an Even Phase Pedestrian Call exists and the Even Phase/FYA is active, Red Revert will be initiated if a serviceable call does not exist across the barrier. If the FYA is active, then the Even Phase Pedestrian will be omitted. If Coordination is active, then Mode 3 will be used.

Mode 3: If an Even Phase Pedestrian Call is serviceable and the FYA is not active, the FYA will be delayed until the walk is completed. If an Even Phase Pedestrian Call exist and the FYA is active, a call across the barrier will be generated on the first non-omitted phase in the sequence if no serviceable call exist. If the FYA is active, then the Even Phase Pedestrian will be omitted.

[See NWS for description of Modes 2 and 4]

Programming the NOT PED Operation:

The 1st screen below is reached by Next-2-2-8-6. It is the 1st of 6 FYLTA screens. From there advance with the ‘A’ key to the 2nd screen below. The last line on this screen is the programming area for this feature. It is called NOT PED MODE. Place a value of 0 – 4 here for each of the FYLTA phase pairs which are used. If the additional Plans A – D are to be used advance to these screens with the ‘A’ key and enter the appropriate values for NOT PED MODE.

 ———————————————————————————————————–

Tech-Tips
by Ryan McKibben

“Ring out” the Field Outputs

When a new cabinet is installed at an intersection it is common practice for the electrician to “ring out” the field outputs to ensure continuity from the output terminals to the field devices. This is done by applying AC power to each output terminal and observing whether or not the associated field device turned on. While this process is adequate to identify errors in the field wiring, it does NOT prove continuity all the way back to the traffic signal controller.

NWS has provided a UNIQUE method for establishing continuity from the controller unit to the field devices called OUTPUT TESTING. The testing is performed through the menu of the controller while observing the field devices.