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IMSA TRAFFIC SIGNAL TECHNICIAN II PRACTICE
EXAM QUESTIONS AND CORRECT ANSWERS
GRADED A+
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 A microprocessor takes appropriate action to control intersection what? - ANSWER: Timing A forerunner of the electronic controllers that we have today was the? - ANSWER: Electro-mechanical controller What year where solid state electronic controllers developed to replace the electro- mechanical controllers? - ANSWER: 1970's What two improvements differentiated electronic controllers from electro- mechanical controllers? - 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? - ANSWER: NEMA TS- 1 The NEMA TS-1 has three connectors which where known as: - ANSWER: A,B, and C connectors
NEMA TS- 1 had how many connectors? - ANSWER: Three 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 The NEMA TS- 1 defined every pin for each connector as either what two connection types? - ANSWER: Input or Output NEMA also allowed manufactures to add an additional feature on the fourth connector. What was this connector know as? - ANSWER: D connector What was the D connector commonly used for? - ANSWER: Communications Pre-emption 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 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 The reinforcing on a concrete strain pole is arranged to primarily withstands loads in how many directions? - ANSWER: One direction
The side of the pole that is to be turned toward the load is called? - ANSWER: The load face Overhead signs used in traffic signals are what two types? - ANSWER: Regulatory signs Street name signs How are "blank-out" signs illuminated? - ANSWER: Internally When are blank-out signs only activated? (2) - ANSWER: Specific times of day Specific events Several considerations must be made before actively engaging in work with a lift truck, these include (5): - 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? - ANSWER: Articulating boom What are some disadvantages of an aerial platform lift?(4) - ANSWER: Only extends vertically Cannot reach as high as boom trucks
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 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) - 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? - 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? - ANSWER: 40% What type of backup power systems require significant manpower and monitoring during use? - ANSWER: Portable generator
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. What are several of the functions a laptop computer can perform in relation to a traffic signal controller?(5) - 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? - ANSWER: Ethernet cable 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
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 Because of the sensitivity to impedance variations, a TDR may be used to: (3) - 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? - ANSWER: Cycle What is the total number of seconds between the start of a specific display until that display comes up again called? - ANSWER: Cycle length In older electro-mechanical controllers the cycle is sometimes referred to as a? - ANSWER: Dial Describes the direction of approach and the maneuver made at the intersection? - ANSWER: (Vehicle) Movement Vehicle movements are usually recorded in a "what" that is typically included in the plans for a traffic signal? - ANSWER: Timing chart
How are vehicle phases typically numbered? - ANSWER: 1 through 8 Which numbers in a vehicle phase a assigned to the through movements? - ANSWER: Even numbers Which numbers are assigned to the left turn movements in a vehicle phase? - ANSWER: Odd numbers Which phases are typically assigned to the major-street through movements? - ANSWER: 2 and 6 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
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 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? - ANSWER: Lead/lag left turn phasing What are the two types of flashing mode operation? - 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? - 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?
- 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. - 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? - ANSWER: Stop time What term defines the minimum initial time that the minimum assured green is displayed? - ANSWER: Minimum green The minimum green time is established to provide what to the intersection. - 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? - 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): - ANSWER: Pedestrian timing Density operations
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
Transit preemption is often called what? - ANSWER: Transit Priority Transit priority can operate by two different techniques: - ANSWER: Green extension Red truncation What has the purpose of transferring the right of way to an emergency vehicle that needs to traverse an intersection? - ANSWER: Emergency vehicle preemption What are the two types of emergency vehicle preemptions? - ANSWER: Stationary Mobile How is stationary emergency vehicle preemption typically activated - ANSWER: When an emergency responder depresses a pushbutton located within the facility. How does a mobile emergency preemption operate? - ANSWER: Transmitter located in the emergency vehicle Receiver located at the intersections How is the preemption input activated typically? - 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? - ANSWER: The clearance of the bridge opening area to permit the gates to be lowered. The omission of phases during the opening.
