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IMSA TRAFFIC SIGNAL
TECHNICIAN 2 EXAM QUESTIONS
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ANSWERS PDF – STUDY GUIDE &
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The traffic field technician is responsible for performing what types of maintenance on signals? - answer-Preventive and Emergency The single most important focus for the traffic signal field technician is? - answer-Safety Three main categories of safety a traffic signal technician is responsible for? - 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? - answer-Bucket Truck Aerial lift (platform truck) While using a bucket truck or aerial lift what implement provides proper protection for the user? - answer-Protective Harness What responsibilities (liability) does a Traffic signal technician have while involved in repair, testing or maintenance? - 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? - answer- Documentation What two instances are documentation required for a traffic signal field technician? - answer-Routine maintenance Emergency repair The "word" public usually represents the following individuals (4): - answer-Road users Area residents / Property owners Elected and appointed officials The media Several means of public interaction are (3): - 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) - 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? - answer- Microprocessor The microprocessor is programmed to recognize what? - answer-Input requests from vehicle detection systems
Other special features What three agencies joined together to help develop the 170 controller? - 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? - answer-Model 170 controller What two specifications does the model 170 controller require? - answer-A specific hardware architecture A specific processor How is the Type 179 controller specification similar to the 170 specification?(2) - answer-Open architecture Allows for interchangeability of components What is the primary difference between the 179 and 170 controller - answer-Uses a different microprocessor Who developed the model 2070 controller? - answer-CALTRANS The 2070 was introduced to supersede which controller? - answer-The 170 controller Which controller is compatible regardless of the manufacturer? - answer-The 2070 controller The 2070 provides more functionality than the 170 because of what features?(3) - answer-Additional processing power
Ability to program in higher level languages Multiple high speed communications ports Define the acronym NTCIP - 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? - answer-The NTCIP The National Transportation Communication for ITS protocol was developed to accommodate what two things? - 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? - 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? - 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) - answer-Equipment Inventory Traffic signal support poles that have a span wire assembly attached to them are called what? - answer-Strain poles Strain poles are designed to withstand the strain from the loads that are placed on them by what two items? - answer-Traffic Signals Support cables
Must be positioned directly below work area. The primary purpose of the traffic signal monitor unit is to act as? - answer-Guard against system malfunction If a malfunction is present the monitoring unit will automatically put the intersection into what mode? - answer-Flashing condition An intersection will remain in flash mode until the monitor unit is? - answer-Reset The CMU and MMU checks the controller for what two things? - answer-Proper power Timing functions What will cause the monitor (CMU) to transfer the intersection into flash mode?(3) - 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 - answer-Program card What are short lengths of conductors on the program card called? - answer-Jumpers On the program card jumpers are installed to tell the unit "what" are considered compatible?(2) - answer-Movements Channels For NEMA type controllers positions not having jumpers are considered as? - answer- Conflicts
Program cards for type 170 controllers use a "what" as a jumper to wire the positions which are considered conflicts? - answer-Diode Why is it important to periodically review the monitor cards? - 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? - answer-Flasher unit The MUTCD requires that when a signal is flashed that the light source be flashed at a rate of? - 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? - answer-Mercury Contactor In a traffic signal cabinet the mercury contactor controls the 120 VAC to all of the? - answer-Load switches These devices are being replaced by many agencies due to what type of concerns? - 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? - answer-Isolators What are the two basic types of isolator or isolator cards? - answer-AC isolators DC isolators What are the most common isolator cards? - answer-Loop detector cards What are two other special purpose cards? - answer-Video detector cards
Serial communication cable What type of software program is typically used as a user interface? - answer-Windows - based graphical user interface What is also known as volt/ohm meter or VOM - answer-multi-meter What is an electronic measuring instrument that combines several functions into one unit? - answer-multi-meter A standard multi-meter includes what three main measurement features? - answer- Voltage Current Resistance A multi-meter provides the ability to measure?(3) - answer-DC and AC voltage DC and AC current Resistance What are the two types of multi-meters? - answer-Analog Digital Digital multi-meter functions:(5) - 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) - 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? - answer- Ammeter Ammeters are also known as?(5) - answer-Clamp-on ammeter Amprobe Clamp meter Current probe Tong tester Which test equipment works by reading the magnetic field around the conductor? - answer-Ammeter What is a unit that a signal technician uses to troubleshoot existing loops and test newly installed loops? - answer-Loop Analyzer What does a loop analyzer measure?(5) - answer-Frequency Relative strength Impedance Change in inductance when vehicle is present Resistance Define TDR? - answer-Time domain reflectometer What is an electronic instrument used to characterize and locate faults in metallic cables? - answer-TDR - time domain reflectometer
The through phases are numbered in which direction and start with which phase? - 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? - answer-Eight-phase What is most commonly associated with a specific vehicular or pedestrian movement?
- answer-Traffic signal phase What is the amount of time that a particular indication is given during a phase? - answer-Interval Each vehicular phase is usually comprised of three specific intervals: - 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? - answer-Ring of a traffic signal controller Controllers typically have what two types of ring operation? - answer-Single Dual The number of rings is dependent upon "what" that is required for the intersection operation? - answer-Phasing When are controllers with 3 or 4 rings typically used? - 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? - answer-Sequential phases In a sequential series of phases how many phases are served at a time? - 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? - answer-Overlaps Overlaps are different from other phases because they cannot be? - answer- Independently called into action There are two basic types of overlaps, known as what? - answer-Independent Parent/child What type of signals have detectors and gap counters, and can skip phases? - answer- Actuated The use of fully actuated instead of non-actuated coordinated phases can do what two things? - 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? - answer-Permissive left turn When are protected only left turns typically used ?(3) - answer-High volume of through traffic More than two through lanes Intersection with constrained sight distance
The number of vehicles that can be queued When establishing the minimum green time consideration must be given to(4): - answer- Pedestrian timing Density operations Controller type Detection design When there are no pedestrian features the minimum green time should be calculated by? - 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? - answer-3 to 7 How many seconds for a minor street through phase? - answer-5 to 15 How many seconds for a major street through phase? - answer-15 to 25 The minimum green time must be long enough to? - 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? - answer- All-red clearance This interval allows for the intersection to "what" before a green phase starts again? - answer-Clear Factors used to determine the most appropriate time for an all red clearance include: - answer-Type of vehicular traffic Driver characteristics
Pedestrian activity in the intersection What is the establishment of a definite timing relationship between adjacent traffic signals? - answer-Coordination timing Traffic signal coordination timings are developed to provide a degree of consistency that should allow traffic to? - answer-Progress through a number of intersections without stopping What within traffic controllers allow for timing plans to transition from one to another gradually so that traffic is not severely disrupted? - answer-Algorithms The amount of time that is allocated to a particular signal phase is the phases? - answer-Split A split includes what three things associated with the phase? - answer-Green time Yellow time Red time What is the transfer of the normal control of signals to a special signal control mode? - answer-Preemption timing Preemption timing has the purpose of servicing? - answer-Railroad crossings Emergency vehicle passage Mass transit vehicle passage Other special tasks Preemption timing control requires "what" of normal traffic control to provide the priority needs of a special task? - answer-Terminating
Railroad preemption should always be set to which level of priority? - answer-The highest Emergency vehicles should be set to which level of priority? - answer-Medium priority If multiple multiple preempts are set to the same priority, how are preempts served? - answer-On a first come first serve basis What are the two primary types of transit vehicle-preemption systems? - answer-Optical Radio What is the most common type of vehicle detection at signalized intersections? - answer-Inductive loop Inductive loops create what type of field for detection? - answer-Electromagnetic What is used to create the electromagnetic field for an inductive loop? - answer-Loop detector amplifier What principle is used by a loop for vehicle detection? - answer-Inductance What are some disadvantages of inductance loops? - 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? - 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? - answer-Frequency change What setting has to be adjusted to eliminate problems with "false calls" on an inductive loop? - answer-Frequency What term is used to define "false calls" and interference from adjacent loops? - answer-Cross-talk In what instances/areas is the loop sensitivity typically increased? - answer-Presence of bicycles Vehicles with high ground clearance As sensitivity is increased a loop detector has a tendency to do what? - answer-"Lock" or place a constant call Advanced loops are usually square point loop detectors that are placed? - answer- Upstream from the stop line The advanced loops detect vehicles and add what to the cycle? - answer-Extension (passage) time How is advanced loop placement calculated using what factors? - answer-Speed of the vehicles approaching the intersection Safe stopping distance Some advantages of video detection systems include: - answer-Can operate during roadway maintenance or construction Provides a quick way to move vehicle detection zones
