Questions with Verified Detailed Answers
Latest 2025
Program cards for type 170 controllers use a "what" as a
jumper to wire the positions which are considered
conflicts? --- correct answer ---Diode
Why is it important to periodically review the monitor
cards? --- correct answer ---To be sure the jumpers are
assigned correctly
What is used to provide the required flash rate when the
signal is in flashing operation? --- correct answer ---
Flasher unit
The MUTCD requires that when a signal is flashed that
the light source be flashed at a rate of? --- correct answer
---Not less than 50 or more than 60 times per minute
What relays are a type of relay that is capable of
switching high levels of current? --- correct answer ---
Mercury Contactor
,In a traffic signal cabinet the mercury contactor controls
the 120 VAC to all of the? --- correct answer ---Load
switches
These devices are being replaced by many agencies due to
what type of concerns? --- correct answer ---
Environmental
What are used in traffic signal controller cabinets that
are solid-state devices that monitor a mechanical switch
or button and report the call status back to the controller
unit? --- correct answer ---Isolators
What are the two basic types of isolator or isolator cards?
--- correct answer ---AC isolators
DC isolators
What are the most common isolator cards? --- correct
answer ---Loop detector cards
What are two other special purpose cards? --- correct
answer ---Video detector cards
Emergency vehicle pre-emption
Load switches in the controller cabinet receive 24V DC
and switch (reroute) the 120V AC to the lamps in the
,signal head. This potentially reduces: (2) --- correct
answer ---The number of faults induced into the
controller from outside the cabinet.
Electrical surges
Why do some agencies operate signals in full operation
mode for a period of time, then switch to flashing mode? -
-- correct answer ---To preserve the battery life
Battery backup system manufactures claim that switching
to red flashing operation at "what battery" level percent
significantly extends run time? --- correct answer ---40%
What type of backup power systems require significant
manpower and monitoring during use? --- correct answer
---Portable generator
Intersections using LED displays use approximately
what % of power that incandescent displays use? ---
correct answer ---10%
What piece of test equipment can be directly connected to
many different traffic signal control equipment groups? --
- correct answer ---Laptop computer
, What are several of the functions a laptop computer can
perform in relation to a traffic signal controller?(5) ---
correct answer ---Set up equipment
Download operational parameters to the equipment
Upload signal system software
Upload traffic signal timing plans
Set up video detection
What are the two typical forms of interconnectivity for
testing equipment? --- correct answer ---Ethernet cable
Serial communication cable
What type of software program is typically used as a user
interface? --- correct answer ---Windows - based
graphical user interface
What is also known as volt/ohm meter or VOM --- correct
answer ---multi-meter
What is an electronic measuring instrument that
combines several functions into one unit? --- correct
answer ---multi-meter
A standard multi-meter includes what three main
measurement features? --- correct answer ---Voltage
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