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IMSA Traffic Signal Technician Level II | Questions and Verified Answers| Grade A| 100% Correct (2024/ 2025) The traffic field technician is responsible for performing what types of maintenance on signals? - CORRECT ANSWER - Preventive and Emergency The single most important focus for the traffic signal field technician is? - CORRECT ANSWER - Safety Three main categories of safety a traffic signal technician is responsible for? - CORRECT ANSWER - Safety of motorist and pedestrians His or her own personal safety Safety of public and personal property Traffic signal field technicians perform several maintenance and repair functions above the ground and roadway typically using what two vehicles? - CORRECT ANSWER - Bucket Truck Aerial lift (platform truck)
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The traffic field technician is responsible for performing what types of maintenance on signals? - CORRECT ANSWER - Preventive and Emergency The single most important focus for the traffic signal field technician is? - CORRECT ANSWER - Safety Three main categories of safety a traffic signal technician is responsible for? - CORRECT ANSWER - Safety of motorist and pedestrians His or her own personal safety Safety of public and personal property Traffic signal field technicians perform several maintenance and repair functions above the ground and roadway typically using what two vehicles? - CORRECT ANSWER - Bucket Truck Aerial lift (platform truck) While using a bucket truck or aerial lift what implement provides proper protection for the user? - CORRECT ANSWER - Protective Harness What responsibilities (liability) does a Traffic signal technician have while involved in repair, testing or maintenance? - CORRECT ANSWER - Legal liability Dealing with the public It is imperative that the traffic signal field technician maintain comprehensive what of all the steps taken during repair and maintenance of traffic signals? - CORRECT ANSWER - Documentation What two instances are documentation required for a traffic signal field technician? - CORRECT ANSWER - Routine maintenance Emergency repair The "word" public usually represents the following individuals (4): - CORRECT ANSWER - Road users Area residents / Property owners Elected and appointed officials The media Several means of public interaction are (3): - CORRECT ANSWER - Mail or email Telephone contact Face to face meetings When dealing with the public, keep in mind that the routines of public users may be disrupted for periods of time during construction. How should a traffic signal field technician interact with the public? (5) - CORRECT ANSWER - Always be polite
Be confident when speaking Communicate clearly in understandable terminology Don't argue or threaten Don't provide information if you are uncertain of its accuracy. Traffic signal controller units of todays traffic systems are controlled by what? - CORRECT ANSWER - Microprocessor The microprocessor is programmed to recognize what? - CORRECT ANSWER - Input requests from vehicle detection systems A microprocessor takes appropriate action to control intersection what? - CORRECT ANSWER - Timing A forerunner of the electronic controllers that we have today was the? - CORRECT ANSWER - Electro-mechanical controller What year where solid state electronic controllers developed to replace the electro- mechanical controllers? - CORRECT ANSWER - 1970's What two improvements differentiated electronic controllers from electro-mechanical controllers? - CORRECT ANSWER - More dependable Added many more features What was the standardization that primarily established a pin configuration in the controller and defined a function for every pin? - CORRECT ANSWER - NEMA TS- 1 The NEMA TS-1 has three connectors which where known as: - CORRECT ANSWER - A,B, and C connectors NEMA TS-1 had how many connectors? - CORRECT ANSWER - Three The NEMA TS-1 defined every pin for each connector as either what two connection types? - CORRECT ANSWER - Input or Output NEMA also allowed manufactures to add an additional feature on the fourth connector. What was this connector know as? - CORRECT ANSWER - D connector What was the D connector commonly used for? - CORRECT ANSWER - Communications Pre-emption Other special features What three agencies joined together to help develop the 170 controller? - CORRECT ANSWER - California DOT City of Los Angeles California New York State DOT What controller is an open-architecture based general purpose microcomputer for traffic control? - CORRECT ANSWER - Model 170 controller
What two specifications does the model 170 controller require? - CORRECT ANSWER - A specific hardware architecture A specific processor How is the Type 179 controller specification similar to the 170 specification?(2) - CORRECT ANSWER - Open architecture Allows for interchangeability of components What is the primary difference between the 179 and 170 controller - CORRECT ANSWER - Uses a different microprocessor Who developed the model 2070 controller? - CORRECT ANSWER - CALTRANS The 2070 was introduced to supersede which controller? - CORRECT ANSWER - The 170 controller Which controller is compatible regardless of the manufacturer? - CORRECT ANSWER - The 2070 controller The 2070 provides more functionality than the 170 because of what features?(3) - CORRECT ANSWER - Additional processing power Ability to program in higher level languages Multiple high speed communications ports Define the acronym NTCIP - CORRECT ANSWER - National Transportation Communications for Intelligent transportation systems Protocol What is a set of standards established by the consortium for controllers, cabinets and other ITS devices? - CORRECT ANSWER - The NTCIP The National Transportation Communication for ITS protocol was developed to accommodate what two things? - CORRECT ANSWER - Needs of subsystems User Services Traffic signal supports and the signal indications and signs that are attached to them should be periodically reviewed to ensure what? - CORRECT ANSWER - That they are performing the function that they were installed to do. Safety of what two entities is the first concern when performing maintenance on traffic signal supports? - CORRECT ANSWER - Workers The public The traffic field signal technician should review the work to be performed to ensure that all necessary "what" is ready and available? (2) - CORRECT ANSWER - Equipment Inventory Traffic signal support poles that have a span wire assembly attached to them are called what? - CORRECT ANSWER - Strain poles
Strain poles are designed to withstand the strain from the loads that are placed on them by what two items? - CORRECT ANSWER - Traffic Signals Support cables The reinforcing on a concrete strain pole is arranged to primarily withstands loads in how many directions? - CORRECT ANSWER - One direction The side of the pole that is to be turned toward the load is called? - CORRECT ANSWER - The load face Overhead signs used in traffic signals are what two types? - CORRECT ANSWER - Regulatory signs Street name signs How are "blank-out" signs illuminated? - CORRECT ANSWER - Internally When are blank-out signs only activated? (2) - CORRECT ANSWER - Specific times of day Specific events Several considerations must be made before actively engaging in work with a lift truck, these include (5): - CORRECT ANSWER - Positioning if the vehicle in or adjacent to the roadway Establishing a temporary traffic control zone Verification of overhead conflicts Planning the work to be performed Using an approved safety harness Bucket trucks may have a boom that is capable of rotating and extending which is called? - CORRECT ANSWER - Articulating boom What are some disadvantages of an aerial platform lift?(4) - CORRECT ANSWER - Only extends vertically Cannot reach as high as boom trucks Must be parked on flat ground Must be positioned directly below work area. The primary purpose of the traffic signal monitor unit is to act as? - CORRECT ANSWER - Guard against system malfunction If a malfunction is present the monitoring unit will automatically put the intersection into what mode? - CORRECT ANSWER - Flashing condition An intersection will remain in flash mode until the monitor unit is? - CORRECT ANSWER - Reset The CMU and MMU checks the controller for what two things? - CORRECT ANSWER - Proper power Timing functions
What will cause the monitor (CMU) to transfer the intersection into flash mode?(3) - CORRECT ANSWER - Loss of power to the controller The 24 volt DC voltage of the controller is lost Time it takes to change from one indication to another is incorrect What does each conflict monitor have that is unique for that particular intersection - CORRECT ANSWER - Program card What are short lengths of conductors on the program card called? - CORRECT ANSWER - Jumpers On the program card jumpers are installed to tell the unit "what" are considered compatible?(2) - CORRECT ANSWER - Movements Channels For NEMA type controllers positions not having jumpers are considered as? - CORRECT ANSWER - Conflicts 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 Current
Resistance A multi-meter provides the ability to measure?(3) - CORRECT ANSWER - DC and AC voltage DC and AC current Resistance What are the two types of multi-meters? - CORRECT ANSWER - Analog Digital Digital multi-meter functions:(5) - CORRECT ANSWER - High input impedance Automatic ranging of measurements Automatic polarity identification Sample and hold circuitry Provides a greater number of testing functions Analog multi-meter functions:(3) - CORRECT ANSWER - Low impedance Fast meter reaction time(measurement time) Provides a quick go or no-go indication What is a device that measures the current flowing through a wire or circuit? - CORRECT ANSWER - Ammeter Ammeters are also known as?(5) - CORRECT ANSWER - Clamp-on ammeter Amprobe Clamp meter Current probe Tong tester Which test equipment works by reading the magnetic field around the conductor? - CORRECT ANSWER - Ammeter What is a unit that a signal technician uses to troubleshoot existing loops and test newly installed loops? - CORRECT ANSWER - Loop Analyzer What does a loop analyzer measure?(5) - CORRECT ANSWER - Frequency Relative strength Impedance Change in inductance when vehicle is present Resistance Define TDR? - CORRECT ANSWER - Time domain reflectometer What is an electronic instrument used to characterize and locate faults in metallic cables? - CORRECT ANSWER - TDR - time domain reflectometer Because of the sensitivity to impedance variations, a TDR may be used to: (3) - CORRECT ANSWER - Verify cable impedance characteristics Splice and connector locations Estimate cable lengths
What is a single sequence of displays that gives each movement at the intersection a chance to proceed through the intersection on a green indication? - CORRECT ANSWER - Cycle What is the total number of seconds between the start of a specific display until that display comes up again called? - CORRECT ANSWER - Cycle length In older electro-mechanical controllers the cycle is sometimes referred to as a? - CORRECT ANSWER - Dial Describes the direction of approach and the maneuver made at the intersection? - CORRECT ANSWER - (Vehicle) Movement Vehicle movements are usually recorded in a "what" that is typically included in the plans for a traffic signal? - CORRECT ANSWER - Timing chart How are vehicle phases typically numbered? - CORRECT ANSWER - 1 through 8 Which numbers in a vehicle phase a assigned to the through movements? - CORRECT ANSWER - Even numbers Which numbers are assigned to the left turn movements in a vehicle phase? - CORRECT ANSWER - Odd numbers Which phases are typically assigned to the major-street through movements? - CORRECT ANSWER - 2 and 6 The through phases are numbered in which direction and start with which phase? - CORRECT ANSWER - Clockwise direction Phase 2 An intersection that has four through phases and four protected left-turn phases is said to be an "what" intersection? - CORRECT ANSWER - Eight-phase What is most commonly associated with a specific vehicular or pedestrian movement? - CORRECT ANSWER - Traffic signal phase What is the amount of time that a particular indication is given during a phase? - CORRECT ANSWER - Interval Each vehicular phase is usually comprised of three specific intervals: - CORRECT ANSWER - Green interval Yellow change interval Red clearance interval What is a series of conflicting phases that occur in an established order, but can never occur simultaneously with each other? - CORRECT ANSWER - Ring of a traffic signal controller
Controllers typically have what two types of ring operation? - CORRECT ANSWER - Single Dual The number of rings is dependent upon "what" that is required for the intersection operation? - CORRECT ANSWER - Phasing When are controllers with 3 or 4 rings typically used? - CORRECT ANSWER - When two or more separate intersections are controlled by a single controller What are phases that cannot happen at the same time because they conflict with one another? - CORRECT ANSWER - Sequential phases In a sequential series of phases how many phases are served at a time? - CORRECT ANSWER - One What are used to provide signalization for specific movements that can be made while some of the other phases of the traffic signal cycle are being served? - CORRECT ANSWER - Overlaps Overlaps are different from other phases because they cannot be? - CORRECT ANSWER - Independently called into action There are two basic types of overlaps, known as what? - CORRECT ANSWER - Independent Parent/child What type of signals have detectors and gap counters, and can skip phases? - CORRECT ANSWER - Actuated The use of fully actuated instead of non-actuated coordinated phases can do what two things? - CORRECT ANSWER - Better balance volume-to-capacity ratios Decrease split failures What phase allows left turning drivers to cross a conflicting traffic stream with care when there are adequate gaps in the opposing traffic flow? - CORRECT ANSWER - Permissive left turn When are protected only left turns typically used ?(3) - CORRECT ANSWER - High volume of through traffic More than two through lanes Intersection with constrained sight distance What phasing occurs when the left turn in one direction gets the left turn arrow before the opposing through movement gets the circular green, then the opposing left turn gets the green arrow after the opposing through is stopped? - CORRECT ANSWER - Lead/lag left turn phasing What are the two types of flashing mode operation? - CORRECT ANSWER - Yellow- red
Red-red What can be planned for either scheduled late-night flashing or scheduled flashing of a signal that is only needed at certain times of the day or week, or emergency? - CORRECT ANSWER - Flashing operation What mode causes flashing circular yellow indications to the major street approaches and flashing red indications are shown to the minor street approaches? - CORRECT ANSWER - Yellow-red flashing mode Flashing red indications are shown to every approach lane to the intersection. This type of flashing operations essentially provides the same type of control as an all- way stop control. - CORRECT ANSWER - Red-red flashing mode What traffic signal control function is typically enabled by an on-site user via a switch selected inside the police panel? - CORRECT ANSWER - Stop time What term defines the minimum initial time that the minimum assured green is displayed? - CORRECT ANSWER - Minimum green The minimum green time is established to provide what to the intersection. - CORRECT ANSWER - Enough time for vehicles stopped between the detector and the stop line to get started and move into the intersection. On what two factors is minimum green time dependent? - CORRECT ANSWER - The location of the detector. The number of vehicles that can be queued When establishing the minimum green time consideration must be given to(4): - CORRECT ANSWER - Pedestrian timing Density operations Controller type Detection design When there are no pedestrian features the minimum green time should be calculated by? - CORRECT ANSWER - At least equal the minimum time it would take a pedestrian to safely cross the intersection. Typically how many seconds for a left-turn phase? - CORRECT ANSWER - 3 to 7 How many seconds for a minor street through phase? - CORRECT ANSWER - 5 to 15 How many seconds for a major street through phase? - CORRECT ANSWER - 15 to 25 The minimum green time must be long enough to? - CORRECT ANSWER - Meet drivers expectations as to how long a green interval should be displayed.
What is the period of time that the signal displays are red for all approaches? - CORRECT ANSWER - All-red clearance This interval allows for the intersection to "what" before a green phase starts again? - CORRECT ANSWER - Clear Factors used to determine the most appropriate time for an all red clearance include:
What has the purpose of transferring the right of way to an emergency vehicle that needs to traverse an intersection? - CORRECT ANSWER - Emergency vehicle preemption What are the two types of emergency vehicle preemptions? - CORRECT ANSWER - Stationary Mobile How is stationary emergency vehicle preemption typically activated - CORRECT ANSWER - When an emergency responder depresses a pushbutton located within the facility. How does a mobile emergency preemption operate? - CORRECT ANSWER - Transmitter located in the emergency vehicle Receiver located at the intersections How is the preemption input activated typically? - CORRECT ANSWER - When the transmitter gets close enough to the receiver for the emitted signal to be detected by the receiver. The three stages of drawbridge preemption are? - CORRECT ANSWER - The clearance of the bridge opening area to permit the gates to be lowered. The omission of phases during the opening. The modification of phase timing after and, opening to clear standing queues. Preemption routines can be directly tied to the bridges via: - CORRECT ANSWER - Control circuitry Queue detectors, down stream from the intersection on the approach to the bridge. Railroad preemption should always be set to which level of priority? - CORRECT ANSWER - The highest Emergency vehicles should be set to which level of priority? - CORRECT ANSWER - Medium priority If multiple multiple preempts are set to the same priority, how are preempts served? - CORRECT ANSWER - On a first come first serve basis What are the two primary types of transit vehicle-preemption systems? - CORRECT ANSWER - Optical Radio What is the most common type of vehicle detection at signalized intersections? - CORRECT ANSWER - Inductive loop Inductive loops create what type of field for detection? - CORRECT ANSWER - Electromagnetic What is used to create the electromagnetic field for an inductive loop? - CORRECT ANSWER - Loop detector amplifier
What principle is used by a loop for vehicle detection? - CORRECT ANSWER - Inductance What are some disadvantages of inductance loops? - CORRECT ANSWER - Can be damaged or broken in areas where freezing and thawing causes the pavement to crack. Can be damaged or broken when a trench is made in the pavement for utility inspection or repair. Installations and maintenance requires closure of travel lanes. An inductive loop assembly consist of? - CORRECT ANSWER - Detector amplifier Lead in cable Insulated loop wire Shallow slot sawed in pavement The amplifier monitors and registers any "what" that occurs when a vehicle enters the detection area? - CORRECT ANSWER - Frequency change What setting has to be adjusted to eliminate problems with "false calls" on an inductive loop? - CORRECT ANSWER - Frequency What term is used to define "false calls" and interference from adjacent loops? - CORRECT ANSWER - Cross-talk In what instances/areas is the loop sensitivity typically increased? - CORRECT ANSWER - Presence of bicycles Vehicles with high ground clearance As sensitivity is increased a loop detector has a tendency to do what? - CORRECT ANSWER - "Lock" or place a constant call Advanced loops are usually square point loop detectors that are placed? - CORRECT ANSWER - Upstream from the stop line The advanced loops detect vehicles and add what to the cycle? - CORRECT ANSWER - Extension (passage) time How is advanced loop placement calculated using what factors? - CORRECT ANSWER - Speed of the vehicles approaching the intersection Safe stopping distance Some advantages of video detection systems include: - CORRECT ANSWER - Can operate during roadway maintenance or construction Provides a quick way to move vehicle detection zones Can provide video images to a remote location Can be used for incident assessment Doesn't require cutting pavement What can Doppler microwave detectors detect? - CORRECT ANSWER - Volume
Occupancy Classification Speed FMCW microwave detectors can detect "what" in addition to volume, occupancy, classification and speed? - CORRECT ANSWER - Vehicle presence What device is used for systems that use field master (closed loop systems) to control local intersections? - CORRECT ANSWER - Dial-up modem How do dial up modems function? - CORRECT ANSWER - Data transmitted to the dial-up line, then over telephone company's infrastructure back to the central computer Dial-up modems provide what in relation to the transition of data? - CORRECT ANSWER - Reliability Efficiency What does the use of fiber optic cables provide an agency? - CORRECT ANSWER - Much higher capability for transmission of data What are the two types of fiber optic cables commonly used? - CORRECT ANSWER
What is the minimum required mode that the intersection should be placed in during repairs? - CORRECT ANSWER - Flashing mode If during a repair, flashing operation isn't available what step should be taken? - CORRECT ANSWER - Notify law enforcement to control traffic What are some benefits of traffic signal scheduled maintenance? - CORRECT ANSWER - Reduce the number of emergency repairs required Reduces delay to the motoring public Reduced travel times Reduced fuel consumption Reduce emissions into the atmosphere In simple terms what is a measurement of raw light? - CORRECT ANSWER - Lumens What is most significant advantage of using LEDs over incandescent lamps? - CORRECT ANSWER - Energy savings The IMSA traffic signal field technician certification is valid for how long? - CORRECT ANSWER - Three years If an equipment restoration effort requires replacement of equipment or specific items, disposition of the removed items should be recorded as: - CORRECT ANSWER - Sent for repair Not repairable/scrapped Scheduled for diagnosis What is usually the most efficient way to verify that the isolated component is the actual cause of the failure or malfunction? - CORRECT ANSWER - Testing What is the most important aspect concerning the testing equipment in relation to the field technician? - CORRECT ANSWER - The technician is familiar with the operation of the equipment and its capabilities