Traffic Signal Senior Field Technician Level III Refresher

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Traffic Signal Senior Field Technician Level III Refresher Session Revised February 4, 2014 Dedicated to providing quality certification programs for the safe installation, operation and maintenance of public safety systems; delivering value for members by providing the latest information and education in the industry. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 2 Intent of Refresher Session: • To briefly review the required technical knowledge and understanding of a typical Traffic Signal Field Technician • Present latest concepts of industry standards in an overview format • Promote group discussion and idea sharing • Time allocated for the session is 6 hours of presentation and 2 hours of open discussions • Questions should be asked as the presentation is underway and the topic is under discussion – others will benefit from any questions asked! • NOTE: This does not necessarily cover all content and/or questions in the associated Traffic Signal Senior Field Technician Level III Exam nor is it limited to the content or questions of the Exam Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 3 Abbreviations: • • • International Municipal Signal Association - IMSA National Electrical Manufacturers Association – NEMA Institute of Transportation Engineers – ITE Manual on Uniform Traffic Control Devices – MUTCD U. S. National Electrical Code (N. E. C. ) U. S. National Electrical Safety Code (N. E. S. C. ) Canadian Electrical Code (C. E. C. ) Federal Highway Administration (FHWA) Transportation Association of Canada (T. A. C. ) Transportation Research Board (T. R. B. ) Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 5 Vehicle Detection - General: • Vehicle detection systems provide the real time information to the traffic signal controller which will allow it to make the necessary decisions as to what phase to service and for how long of a time period. • When considering a vehicle detection system for a signalized intersection, the following should be evaluated: • Type of detection system • Placement of detectors for an approach • Quantity Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 6 Vehicle Detection - General: • It is important to understand all of the characteristics of a candidate vehicle detection system before it is installed. This would include the following: • Presence or pulse detection • Installation in existing environment • Maintainability • Ability to meet operational requirements • Ability to interface with control cabinet architecture Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 7 Vehicle Detection - Loops: • Operating within the design inductance will ensure proper loop performance/detection: - Ex: NEMA – 50 to 1000 microhenrys - Ex: Manufacturer range – 20 to 2500 microhenrys • Alternate Loop dimensions and configurations should be considered in order to best match the intended purpose (Stop line detection, queue loop, bicycle, counting, etc. ) • Loop lead-in cable should be spliced (and soldered) at road side to the loop wires and should have the cable “shield” bonded to earth ground at the traffic cabinet end ONLY Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 8 Vehicle Detection - Loops: • Inductance loops are sensitive to other electrical fields in close proximity, including underground/overhead power lines. • Additionally, they will be affected by the presence of other large metallic objects such as man-holes. • Complete cleaning of the slots before wire installation will significantly affect longevity of loop operation. • Interconnecting several loops can be done in “series” and/or in “parallel”, each having a benefit and disadvantage, review required/desired operation before finalizing connection. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 9 Vehicle Detection - Loops: • Loop inductance increases with the number of turns of wire (formula: L=P (3. 28)(N 2+N) /4 – where L = loop inductance; P=Perimeter in meters; N=number of turns) • Typically the overall area of a loop should not exceed 18. 5 sq. m (200 sq. ft. ) • Lead-in inductance calculation: . 7544 microhenrys per meter (. 23 microhenrys per foot) Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 10 Vehicle Detection – Loops: • Sensitivity settings programmed in the loop amplifier determine threshold level at which changes to inductive loop frequency will trigger a vehicle detection. • Pulse detection will provide a 125 millisecond output from the amplifier once a vehicle has been detected. This is a one time output per vehicle and this output will not be active again until the vehicle leaves the detection zone and another vehicle enters it. • Presence detection will provide a constant output from the loop amplifier once a vehicle has been detected. This output will remain constant as long as a vehicle is in the detection zone up until the time at which it is “tuned-out”. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 11 Vehicle Detection - Video: • Video detection operation is very dependant on the view area/angle of the video “field of view”. • A key consideration is to ensure that the video image of the detection area is not partially or fully blocked by a passing vehicle (such as a truck or bus that crosses in front of the detection zone for a far side detection zone) – typically referred to as “occlusion”. • Other problems occur when the camera is setup too low (too sharp an angle to discern a vehicle) and/or with the horizon visible (sun rise or sunset saturates the detection zone image) – note all video detection cameras should have a “sunshield”. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 12 Vehicle Detection - Video: • Two rules of thumb for camera height mounting are: • mount camera at least 6 m (20 ft. ) above roadway, if possible • approximately . 3 m (1 ft. ) height for every 3 m (10 ft. ) between the camera and the desired detection zone. • Video detection is dependant on the occurrence of change in the image within the programmed detection zone. It is very dependant on contrast. Areas of low contrast within the detection area are typically referred to as "fog zones". Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 13 Vehicle Detection - Video: • With consideration of the electronics in both the camera and the controller cabinet, the installation should include lightning protection on both the data and power cable/wires. • Maintenance of the video detection system should include alignment checks to ensure that the programmed detection zones are still proper, and that the camera “field of view” has not been altered. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 14 Vehicle Detection – Other Technologies: • Most other forms of non-invasive detection use some form of frequency based signal to determine if there is a vehicle in the detection zone area. • This type of detection is not influenced by environmental consideration such as “sun in the lens”, “fog”, etc. • A typical microwave detector can detect motion up to approximately 110 m (350 ft. ). • Ultrasonic detectors can provide constant detection as long as a vehicle resides in the detection zone. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 15 Vehicle Detection – Other Technologies: • Acoustic detection can be used, with a maximum detection distance of approximately 20 m (60 ft. ). • Magnetometers are vehicle detection devices which sense a change in the earth’s magnetic lines of flux. Once the system is installed and properly set up, large metallic objects entering in a close proximity to the magnetic detectors will alter these lines of flux. This alteration in flux lines will be sensed by the amplifier and detection will occur. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 16 Vehicle Detection – General: • When setting up a vehicle detection system one should consider the implication of the field wiring in order to provide for separate leads and isolated detection zones, back to the controller cabinet, in order to accommodate the most flexible arrangement and settings per detection zone (such as phase assignment, detector switching, delay, extend, etc. ) • An additional benefit of separate detection zone wiring is the ability (if your controller is capable) to log detector failures (no calls, excess calls, etc. ), review operations for maintenance purposes and the collection of vehicle traffic flow data. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 17 Vehicle Detection – General: • NEMA specifies settings for delay in the range of 0 -255 seconds. • NEMA specifies settings for extension in the range of 0 -25. 5 seconds. • With a NEMA TS 2 Type 1 controller and cabinet assembly, delay and extension timing should be programmed in the controller unit as opposed to in the detector amplifier. This is necessary since there is no terminal based “green gating” input available under NEMA TS 2 Type 1 assemblies. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 19 Load switches: • Load switches provide the interface from low voltage controller signals to high voltage (120 VAC) field connections to illuminate the desired signal indication. • Typical load switches have 3 LED’s on the front, these indications relate to the inputs to the load switch from the controller. Some loads switches have 6 LED’s providing an indication of both inputs and outputs. • Problems with load switches can be complete failure placing outputs on all the time at 120 VAC or can be leakage problems with voltage ranging anywhere from 1 VAC up to 120 VAC on the output. • NEMA requires that switching from ON to OFF occurs in the range of 6 to 16 VDC. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 21 Cabinet Monitors: • There are essentially two types of monitoring devices available in the marketplace: 1. Conflict Monitor Unit (CMU) • This type is used for NEMA TS-1 assemblies. 2. Malfunction Management Unit (MMU) • This type is used for NEMA TS 2 and 2070 assemblies. 3. Conflict Monitor Unit (CMU) • This type is used for 170/179 assemblies. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 22 Cabinet Monitors: • • • CMU’s, MMU’s ensure “to the best of their ability” that there will be no circumstances of a conflicting signal indication at the intersection (i. e. : having the Main Street Green on at the same time the Side Street Green is on). The use of this technology effectively minimizes the potential litigation issues that may arise from operating a traffic signalized intersection – signals are placed in a FLASH state upon conflict/failure detection. To accomplish this there are separate inputs to each conflicting channel in a CMU/MMU. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 23 Cabinet Monitors: • A NEMA MMU has the option to have either: • 4 inputs per channel (referred to as the Type 12) • 3 inputs per channel (referred to as the Type 16) this type is intended to be wired on a per load switch basis as opposed to by signal phase • A NEMA CMU has 4 inputs per channel monitoring Red, Yellow, Green and Walk field outputs. • There is a MMU input defined and required by NEMA which configures the unit to operate as either a 12 channel conflict monitor or a 16 channel MMU. This MMU input is called “type select”. In a TS 2 cabinet, this input is grounded to configure the monitor to operate as a 16 channel MMU. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 24 Cabinet Monitors: • • • For NEMA monitors, copper jumpers are added to the programming card to provide for channel compatibility. For 170/179/2070 monitors, existing diode jumpers are removed from the programming card to provide channel compatibility. Some monitors have enhanced capabilities/features such as logging failure events, troubleshooting aids, and expanded user display. A NEMA monitor is set to trigger a conflict within 450 milliseconds of sensing the conflict. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 25 Cabinet Monitors: • • • It should be noted that an incandescent lamp can be illuminated (enough to see with the naked eye at night) at voltages as low as 30 volts (could be leakage from a load switch), hence the monitors are set to trigger with conflicts at a voltage of 25 VAC. When a conflict or failure occurs and the monitor “trips” it is important that the responding persons record the status of any indicator lights or screen displays PRIOR TO HITTING THE RESET BUTTON!! This recorded information is imperative for proper trouble shooting of the potential problems that led to the conflicting signal indication or overall monitored equipment failure. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 26 Cabinet Monitors: • • Certain failures cause a “latching” state (stays in FLASH until the reset button is pressed) in a conflict monitor (i. e. : conflicting channels) as opposed to detection of a power failure which will allow the monitor to reset automatically, if programmed by the user, upon application of proper power. Conflict monitors also typically monitor the other equipment within the control cabinet – one such monitor function is the 24 VOLT MON (sensing the properating voltages in the traffic controller unit) which upon sensing this input at less than 18 Volts DC will cause the monitor to trip Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 27 Cabinet Monitors: • In the case of a conflict occurring prior to a power failure, the monitor WILL NOT automatically reset upon power restoration. • Red/Don’t Walk monitoring (NEMA) requires the presence of 60 +/- 10 volts RMS AC in order to avoid the detection of a missing indication (which will cause a failure detection). Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 28 Cabinet Monitors: • The CMU/MMU should be tested as part of a regular maintenance routine – a minimum of once per year as follows: • • A “bench test” should be performed using a manufacturer approved tester unit. An in-cabinet test should be performed to ensure all field wiring being monitored is properly connected and being sensed by the monitor. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 1975 NEMA Pre-Standards 1976 TS-1 1992 TS-2 Caltrans / NYDOT 1979 170 1985 179 1990 170 E 1995 2070 ATC 1999 - Developing Courtesy of VHB Inc. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 31 Controller Units (General): • • • The “brains” of a traffic signalized intersection. NEMA TS 1 – front panel multiple connectors (A, B, C and optional, manufacturer-specific D) that operate at 24 VDC with the other cabinet components. NEMA TS 2 – front panel connectors (PORT 1 for cabinet operations – minimum of 3 PORTS to be provided) that operate as “data channels” with other cabinet components. 170/179/2070 Controller - rear panel connectors that operate at 24 VDC with other cabinet components (C 1 for Input/Outputs). It should be noted that 2070 controllers provide for a variety of different interface options. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 32 Controller Units (General): • • NEMA controllers have manufacturer proprietary firmware based on the specific microprocessor resident in the controller. The 2070 controller operates on proprietary software but is based on a common operating system OS-9. 170/2070 controllers are typically purchased separately from controller firmware. This allows for maximum flexibility in operational functions to meet specific agency or application requirements. Controller hardware and firmware specifications are set by standards development organizations such as NEMA (TS 1 and TS 2) or public agencies such as Caltrans (170/2070). Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 33 Controller Units (General): • Communication protocols between controllers and any associated systems have historically been manufacturer proprietary based. NTCIP and other ITS based data packaging and communications protocols may provide for interchangeably and interoperability between different manufacturer’s devices if properly specified and applied. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 34 Controller Units (General): • • Inputs from the traffic controller in the NEMA TS 1, 170/179/2070 controller platforms require that a controller input modifier be connected to logic common (LOW) to turn ON the associated controller input function. A HIGH (24 VDC) voltage level means the controller input or output is in an OFF condition. Traffic controllers with more than 4 phases typically are configured with two RINGS (phases 1 -4 in RING 1 and phases 5 -8 in RING 2). In the 170/179/2070 controller platform, an “I” and/or “J” file relates to the NEMA “Input File”. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 35 Controller Units (General): • • • Signal phasing for an intersection is based on traffic engineering design. It can vary from a simple two phase operation, through an eight phase, dual ring quad operation. The number of phases and overlaps possible depends on the type of controller, controller size, firmware level and manufacturer. There is controller firmware available to support up to a 40 phase operation. Some controllers are able to monitor their internal operations for properation, For example, in a NEMA TS 2 type 1 platform, the SDLC communications line is monitored such that if a problems occurs with this data link, an associated report will be displayed on the controller. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 36 Controller Operation (General): • • The settings range from establishing the basic time intervals (Walk, Min Green, etc. . ), to specialty data sets for accommodating alternate phase sequences to provide for special conditions such as pre-emption. Some intervals could be considered “critical” such as the vehicle clearance intervals of Yellow and All Red, and the pedestrian clearance (FLASHING DON’T WALK). Yellow interval time should be in the range of 3 to 6 seconds in duration per MUTCD. FLASHING DON’T WALK timing is defined by the MUTCD and is currently set at 4 feet per second from curb to curb. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 37 Controller Operation (SEQUENCE): • Discussion of : • Rings • Barriers • Phase assignments • Vehicle • Pedestrian • Phase compatibility • Dual Ring operation • Overlaps Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 38 Controller Operation (SEQUENCE): • • • With the sequencing of a dedicated left turn movement, if a left turn precedes (comes on before) the associated through movement, it is referred to as a “Leading Left Turn”. If it follows (comes on after) the associated through movement, is it referred to as a “Lagging Left Turn” Advance left turns can be operated as either: • Permissive Only • Protected / Permissive Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 39 Controller Operation (SEQUENCE): • • When using Protected / Permissive, one important note when setting/selecting a phase sequence, is to make sure that the programming is not such so as to allow a “Yellow Trap” situation (when a YELLOW ball is indicated in one direction while a GREEN is indicated in the opposing direction. ) Some controllers have a software programmable setting to avoid this condition – called “Back-up Protection”. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 40 Controller Operation (ACTUATIONS): • • Although general signal operation is simple in principle there are many options and derivations that can be set to occur based on detection, signal coordination, etc. Some specific programming considerations could be as follows: • Fixed time (recalls on Peds and Vehicles) versus actuated • Volume density (with variable Min Green, Gap Reduction, etc. ) • Time-of-Day (TOD) settings that affect actuated operation may be to place recalls on phases, phase selections/omissions, implement coordination, etc. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 41 Controller Operation (Coordination): • • • Preparing a signal controller to operate in a coordinated manner (with respect to nearby intersections – typically those within 800 m ( ½ mile) should be coordinated) requires some forethought and planning Typically a study is undertaken to establish the desired “Timing Plan” A “Timing Plan” typically consists of establishing: - Cycle Length is the time for the controller unit to serve all phases and associated vehicle and pedestrian movements. - Offset is the time relationship determined by the difference between a defined point in the coordinated green and a system reference point. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 42 Controller Operation (Coordination): • • • - SPLIT is the time that is assigned to each phase/movement in order to maintain a constant Cycle Length. It should be noted that the OFFSET is related to the point in time when the Green on the Coordinated Phase either begins or ends (this is programmable). The point at which Coordinated Phase Green is released to Yellow is referred to as the “YIELD Point”. If not careful in determining the required SPLIT time for the non-coordinated phases the necessary Ped. Times will exceed the allocated SPLIT time and cause the unit to perpetually drift in and out of coordination. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III t Coordinated Phase Green A Street Main Street Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA B Street d 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III t Coordinated Phase Green A Street Offset Main Street Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA B Street d 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III t Green Band Coordinated Phase Green A Street Offset Main Street Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA B Street d 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 49 Controller Operation (Coordination): • A signal coordination “Timing Plan” with the associated OFFSET’s for each intersection is sometime illustrated using a Time-Space-Diagram (TSD) which illustrates: - Time on the vertical axis - Distance on the horizontal axis - Green/Yellow/Red for Main Street at each intersection as it relates to the Cycle Length and common time - Angled lines between intersections illustrating when the signal will be GREEN for arriving vehicles based on when they left the last intersection, these are based on estimated SPEEDS and related distances to travel -A straight horizontal line indicating the relative offsets between the intersections Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 50 Controller Operation (Coordination): • Typically signal coordination can be accomplished on the basis of either: - MANUAL mode – the operator forces a specific Timing Plan for each intersection to be in effect - TOD selection/program of each intersection Timing Plan to have in effect (based on time of day, day of week , week of year, special holiday day, etc. ) - Traffic Responsive/Adaptive, where the traffic system monitors actuations throughout a designated geographic area and determines what is the most appropriate Timing Plan for each intersection to match the conditions being observed Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 51 Controller Operation (Preemption): • • Special settings are typically available for establishing alternate phase sequences to accommodate nearby trains, emergency vehicles, special transit treatment, etc. Rail Preemption (for clearing nearby railway tracks from queued vehicles, stop vehicle prior to tracks) – typically uses a “harsh” alteration of signal sequence and timings. Emergency Preemption (for getting the signal to be green for an approaching emergency vehicle) – typically uses a “harsh” alteration of signal sequence and timings. Transit Priority (making minor modifications in attempt to minimize transit delays) – typically uses a “harsh” alteration of signal sequence and timings. (Green Extension/Early Return) Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 53 Grounding and Bonding: • • Grounding is used to limit the voltage to ground potential during the normal operation of an electrical system to minimize excessive electrical energy due to lightning, line surges or unintentional circuit contact with higher voltage lines and to stabilize the voltage to ground during normal operations. (IAEI Soures Book on Grounding, 7 th Edition) Grounding of electrical equipment is not for the purpose of clearing ground faults. (Mike Holt’s NEC Series, Grounding and Bonding, Volume 2) Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 54 Grounding and Bonding: • Bonding is the electrical connection of conductive materials that may become energized under certain conditions to provide a low impedance path for clearing ground faults that would otherwise remain at an electrical potential above earth potential thus creating a shock hazard. (National Electric Code, 2008 Edition) Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 55 Grounding and Bonding: • • “The grounding system in the cabinet shall be divided into three separate and distinct circuits (AC neutral, Earth Ground, Logic Common), all of which shall be connected together at a single point. . . at the time of delivery” ( NEMA TS 2, Version 02. 06, Section 5. 4. 2. 1) “Field installation practices may require separating AC Neutral and Logic Common from Earth Ground within the cabinet. ” ( NEMA TS 2 Version 02. 06, Section 5. 4. 2. 1) Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 56 Grounding and Bonding: • Testing and inspection of the grounding and bonding system should be conducted as part of the signal inspection and conducted periodically as part of a preventative maintenance program. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 58 Cabinet Installation/Maintenance: • • • Ground mounted cabinets are installed on a concrete foundation; typically with a pad for a technician working area. Other cabinet installations may include side of pole mounting and pedestal mounting at a height suitable for the technician to comfortably work on. In a ground mounted cabinet installation, a seal is applied between the cabinet and the foundation to prevent dust and moisture from entering. Care and attention must be taken to ensure proper grounding and bonding at the cabinet (local electrical codes dictating). Inside cabinet area should be kept tidy (including bundling of wires, etc. ) at all times. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 59 Cabinet Installation/Maintenance: • • Tagging of all incoming wiring should be performed (i. e. : all signal wires/cables, all detector cables, etc. ). Preventative Maintenance should be performed on a regular basis (determined by owner/agency). Preventative Maintenance should be performed at minimum once per year. This would typically consists of tasks, including but not limited to, cleaning of cabinet, tightening screw terminal, checking fan/heater, replacing door air filter, monitor testing, controller testing, confirmation of detector operation, review of controller timing/ programming, etc. IMSA/ITE Traffic Signal Maintenance Handbook Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 60 Cabinet Installation/Maintenance: • • • All activities (either someone entering the cabinet or working on the traffic signal in any manner), whether Preventative or otherwise should be noted in a Cabinet “Log Book”. The Cabinet “Log Book” can go a long way in demonstrating “Due Diligence” and minimizing legal liability in the case of a “claim” against the owner agency or maintenance contractor. There is a legal duty for the owner/agency to maintain the traffic signals in properating condition (functionally as well as displays illuminating properly). Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 61 External Cabinet Components (Junction/Pull Boxes): • Junction/pull boxes should be installed level with the surrounding area. • Junction/pull boxes should have their lids (if steel) electrically bonded. • If installed in roadway (or travel area) the junction/pull box lid must have an adequate load capability. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 62 External Cabinet Components (Poles): • • Many types of signal poles are used (i. e. : wood with overhead using span wire, steel, concrete, aluminum, etc. ). Most important consideration is the structural integrity of the installation of the pole (specifically the soil that it or its associated base, is imbedded in). Poles should be visually checked on a regular basis for signs of structural fatigue/cracking, damage, and aesthetics (paint condition). Any problems noted should be addressed as soon as possible through regularly scheduled maintenance. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 63 External Cabinet Components (Signal Heads): • • The inside of signal visors, any louvers or fins, and the front surface of any backplates shall have a “dull black finish” (per U. S. MUTCD) to minimize reflected light and to increase contrast between the signal section and its background. Overhead vehicular signal heads shall be mounted with the bottom of a signal housing at least 4. 6 m (15 ft) and the top of the signal housing not more than 7. 8 m (25. 6 ft) above the pavement (per U. S. MUTCD). Far side signal heads shall be mounted within the 20 degree cone (right or left of center at Stop Line) sightline. Overhead signal heads shall not be mounted closer than 2. 4 m (8 ft) apart. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 64 External Cabinet Components (Signal Heads): • • Vehicle signal head lenses come in two basic sizes: - 200 mm (8 inches) - 300 mm (12 inches) The 200 mm heads can be used if the distance from the stop bar to signal head is between 12 m (40 ft) and 45 m (150 ft). The 300 mm heads are typically used if the distance from stop bar to signal head is greater than 35 m (120 ft). Some agencies decide to standardize on 300 mm (12 inches) for consistency of display and maintenance inventory considerations. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 65 External Cabinet Components (Signal Heads): • • Pedestrian signal displays shall have the symbol a minimum height 150 mm (6 inches). Separate 2 -section (WALK and DON’T WALK) or single “overlay” section pedestrian heads are available. Pedestrian signal heads shall be mounted with the bottom at a minimum height of 2. 1 m (7 ft) and not higher than 3 m (10 ft) above the sidewalk level. Note: the lamp socket for an incandescent signal section rotates to allow for placement of the bulb filament in the upward “horseshoe” position. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 66 External Cabinet Components (Signal Heads): • • Light Emitting Diode (LED) based signal displays are common place now (as opposed to the historical use of incandescent light bulb and glass lenses). LED’s are extremely efficient for power consumption. The manufacturing of LED signal heads was initiated with RED (common LED color for many non-traffic applications), and with finally WHITE being released (hardest color to simulate using LEDs). LED signal heads are being manufactured based on the ITE standards and specifications, which define items such as luminous intensity & distribution, chromaticity, power factors, etc. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 67 External Cabinet Components (Signal Heads): • • LED pedestrian signal heads made the possibility of single section overlay arrangements. LED signal lenses should be checked for decrease brilliance after being in service for a few years (expected life expectancy is usually 5 -8 years). Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 68 External Cabinet Components (Cable/Wire): • • • All cabling/wiring within a signalized intersection (as with any other electrical facility) MUST MEET ALL ASSOCIATED ELECTRICAL CODES. Signal wiring (between the controller cabinet and the signal pole) is commonly accomplished with IMSA specified cable (i. e. : IMSA 19 -2 and IMSA 20 -2). IMSA 20 -2 has a black polyethylene (PE) jacket. IMSA 19 -2 has a black polyvinyl chloride (PVC) jacket. IMSA also has specifications for the detector lead-in cable (i. e. : IMSA 50 -2). Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 69 External Cabinet Components (Cable/Wire): • • • All terminations and or splices shall be accomplished with the manufacturer recommended (or specified by designer) methods (i. e. : lugs with corrugated interiors for solid wire, etc. ) All cable and wires shall be tagged at any splice point and termination point (typically within 50 mm (2 inches) of the end of the wire being terminated or spliced). Bonding shall be maintained between all electrically conductive structures and equipment within the signal installation. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 70 External Cabinet Components (Cable/Wire): • Electrical isolation for pedestrian pushbutton wiring is suggested to ensure both pedestrian safety (from potential electric shock in the case of an equipment failure) and equipment safety (from external electrical noise). Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 72 Communications/Interconnect: • • When individual signalized intersections are integrated in to a signal system they require the ability to communicate to a master controller or a central computer. Several options exist for providing this communication, some examples of mediums are: - Hardwire (twisted pair copper ) - Radio - Fiber optic cable Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 73 Communications/Interconnect (Twisted Pair): • • Twisted pair cable provides a point to point connection between all system based traffic signal controllers. Cable types are specified by IMSA (i. e. IMSA 19 -4 and 20 -4) Proper splicing and termination methods are critical to ensure stable communication is attained. This type of line may be owner/agency owned or it may be leased from a local telephone company. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 74 Communications/Interconnect (Radio): • • Radio can operate based on a fixed broadcast frequency or can use a form of spread spectrum. Fixed frequency radio requires approval from the FCC (CRTC in Canada). Spread Spectrum radio utilizes an open (open to anyone who wants to use it) frequency range and hence does not require specific approvals. Antenna types, location and alignment are very important in effort to maintain “line-of-sight” for optimal operation – “Field Strength” meters are used for setup. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 75 Communications/Interconnect (Fiber Optics): • • • The use of fiber optic cable provides the most “expansive” capabilities for communications between traffic signal and other ITS devices. Fiber optic cable has very large “bandwidth” allowing for significant amounts of data to be transferred between devices. Proper termination of fiber optic cable is critical to operation. Care should be taken to ensure that the proper connector is used, such as ST, SC, etc. Fiber optic cable sheath colors identify the type (mode) of transmission. Yellow is used to identify single mode and orange is used to identify multimode. Single mode fiber is best for longer dedicated runs Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III 76 Communications/Interconnect (Fiber Optics): • • • Two primary considerations when installing fiber optic cable are: - Bending radius - Pulling tension Fiber optic cable should be tested with an Optical Time Domain Reflectometer (OTDR) prior to installation and after installation (with all the connectors in place). Results of both tests should then be compared so as to note any significant or unexpected light losses (expressed in Decibels (d. B)). Wavelengths are measured in nanometers. Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014

Traffic Signal Senior Field Technician Level III Refresher Session Revised February 4, 2014 Conclusion – Discussion Time Prepared by: IMSA Traffic Signal Committee Copyright 2005 IMSA 3 rd Revision, February 4, 2014