Light Emitting Diode (LED) Traffic Signal Head Art. 1078.01 ASTM A 475, Utilities Grade or better. The other appurtenances shall be galvanized according to AASHTO M 232 and be according to the following. The anchor shall have a minimum expanded area of 125 sq in. (81,000 sq mm). The anchor rod shall have a nominal diameter of 5/8 in. (16 mm) and a minimum breaking strength of 11,500 lb (51,200 N). The guy guard shall be 7 ft (2.1 m) long, tapered, and made of 18 gauge steel minimum, except for sidewalk guys, the guy guards shall be made of heavy-duty plastic. The guy wire clamps shall be three bolt and have a minimum breaking strength of 11,500 lb (51,200 N). The dead-ends shall be made of the same material as the guy wire. SECTION 1078. LIGHT EMITTING DIODE (LED) TRAFFIC SIGNAL HEAD
1078.01 Light Emitting Diode (LED) Signal Head and Optically
Programmed LED Signal Head.
a.Face. The signal face shall be of sectional design and expandable.
b.Housing and Door. The polycarbonate housing or door shall be made of Ultra-Violet stabilized polycarbonate resin and shall be molded in one piece with a minimum thickness of 0.09 in. (2.25 mm). The top and bottom of each housing shall have an opening to accommodate standard 1.5 in. (38 mm) pipe fittings and brackets. The top and bottom openings shall each have an interlocking ring integral with the signal section. The locking ring shall have 72 teeth, permitting rotation of the signal section in five degree steps. The door shall be securely attached to the housing with stainless steel hardware. All access openings shall be provided with neoprene or rubber gaskets. Each signal section shall attach to each adjoining section in the signal head with sufficient strength to prevent separation or movement between the sections.
c.Optical Unit.
1.The LED signal section shall be according to the following.
a.General Requirements. The LED signal head shall fully comply with the Institute of Transportation Engineers (ITE) LED purchase specification, “Vehicle Traffic Control Signal Heads: LED Circular Signal Supplement”, and “Vehicle Traffic Control Signal Heads: Art. 1078.01 Light Emitting Diode (LED) Traffic Signal Head LED Vehicle Arrow Traffic Signal Supplement”, in effect on the date of invitation for bids, except as modified herein.
b.Physical and Mechanical Requirements. The power supply for the LED module shall be integrated with the unit.
c.Photometric Requirements. The illuminated portion of the arrow module shall be uniformly and completely dispersed with the LEDs.
d.Electrical Requirements. The maximum and nominal wattage requirements for 12 in. (300 mm) circular and arrow modules shall be as follows. Module Type Maximum Watts (W) at 165 F (74 C) Nominal Watts (W) at 77 F (25 C) 12 in. (300 mm) Yellow Circular 25 22 12 in. (300 mm) Yellow Arrow 12 10 12 in. (300 mm) Green Circular 15 15 12 in. (300 mm) Green Arrow 11 11 12 in. (300 mm) Red Circular 17 11 12 in. (300 mm) Red Arrow 12 9 The individual LEDs shall be wired such that failure of a single LED shall result in loss of light from only that LED.
2.The optically programmed LED signal section shall be according to the following.
a.LED Lamp Module. The LED lamp module shall be designed and constructed to be installed in a programmed visibility signal housing without modifications to the housing. The chromaticity of the module shall comply with the ITE VTCSH-STD Part 2 specifications. The nominal wattage requirements for 12 in. (300 mm) circular modules shall be as follows. Module Type Nominal Watts (W) at 77 °F (25 °C) 12 in. (300 mm) Yellow Circular 17 12 in. (300 mm) Green Circular 14 12 in. (300 mm) Red Circular 10 Light Emitting Diode (LED) Traffic Signal Head Art. 1078.01 The individual LEDs shall be wired such that failure of a single LED shall result in loss of light from only that LED.
b.Optical Limiter-Diffuser. The optical limiter-diffuser shall provide an imaging surface at focus on the optical axis for objects 900 to 1,200 ft (275 to 365 m) distance and permit an optical masking tape to be variously applied as determined by the desired visibility zone. The optical limiter diffuser shall be provided with positive indexing means and composed of heat-resistant glass.
c.Objective Lens. The objective lens shall be a high resolution planar incremental lens hermetically sealed with a flat laminate of weather-resistant acrylic. The lens shall be symmetrical in outline and capable of being rotated to any 90 degree orientation about the optical axis. The projected signal indication shall be capable of being veiled anywhere within 15 degrees of the optical axis. The indication shall not result from external illumination and shall be according to the ITE Standards.
d.Photo Control. The photo control shall comprise an integrated, directional light sensing and regulating device interposed between lamp and line wires. The lamp intensity shall not be less than 37 percent of uncontrolled intensity at 1,000 footcandle (10,000 lux) and shall be reduced to 15 ± 2 percent of maximum at less than 1 footcandle (10 lux). The response shall be proportional and essentially instantaneous to any detectable increase of illumination from darkness to 1,000 footcandle (10,000 lux) and damped for any increase from 1,000 footcandle (10,000 lux). The photo control shall be compatible with 60 Hz input and responsive within the range of 105 to 135 VAC.
d.Terminal Block. Each signal face shall contain a terminal block with at least ten terminals.
e.Visor. The conventional signal section shall be furnished with a tunnel type visor, and the optically programmed signal section shall be furnished with a cutaway type visor. The visor shall be a minimum of 0.05 in. (1.2 mm) in thickness. The visor for a 12 in. (300 mm) signal section shall be a minimum of 9 in. (225 mm) in length.
f.Mounting Bracket. The mounting bracket shall be made of steel or aluminum. Signal heads with more than one signal face shall be furnished with terminal compartments. Each terminal compartment shall contain a terminal block with at least 16 terminals.
g.Finish. The aluminum signal head shall be painted according to Section 851, except the primer shall be applied to all areas. For polycarbonate signal heads, the colors specified in Section 851 shall be an integral part of the material composition. Art. 1078.02 Light Emitting Diode (LED) Traffic Signal Head
1078.02 Light Emitting Diode (LED) Pedestrian Signal Head. The
pedestrian signal head shall be according to the MUTCD and the ITE Standards current at the time the project is advertised.
a.Housing and Door. The housing and door of each section shall be according to Article 1078.01(b).
b.Optical Unit. Only symbolic walk (walking person), don’t walk (upraised palm), and number indications shall be used. The pedestrian signal heads shall be according to the ITE publication, “Pedesdrian Traffic Control Signal Indications”, in effect on the date of invitation for bids, except as modified herein. The nominal message bearing surface of pedestrian signal heads shall be 12 in. x 12 in. (300 mm x 300 mm) or 16 in. x 18 in. (400 mm x 450 mm). The minimum height of the symbols and numbers displayed shall be 9 in. (225 mm). The LED signal heads shall also meet the following requirements.
1.Physical and Mechanical Requirements. The power supply for the LED module shall be integrated with the unit.
2.Photometric Requirements. The illuminated portion of the module shall be uniformly and completely dispersed with the LEDs.
3.Electrical Requirements. The nominal power consumption by the countdown pedestrian signal head shall be 20 watts or less. The individual LEDs shall be wired such that failure of a single LED shall result in loss of light from only that LED.
c.Terminal Block. Each pedestrian signal face shall contain a terminal block with at least eight terminals.
d.Visor. The visor for each signal shall be either the tunnel visor or the low profile visor. The tunnel visor shall be according to Article 1078.01(e). The low profile visor shall be no deeper than 2 in. (50 mm) and shall consist of louvers to provide, shade from the direct sun rays and a cutoff angle restricting the unintended viewing of the signal indication. The low profile visor shall be impregnated black polycarbonate, eliminating the deterioration of the color and texture of the visor from the exposure to the ultraviolet sun rays.
e.Mounting Bracket. The mounting bracket shall be according to
Article 1078 — 01(f), except no terminal compartment will be required.
1078.03 Traffic Signal Backplate. The traffic signal backplate shall be made
of sheet aluminum, composite laminated aluminum, sheet ABS plastic, or ABS plastic (vacuum formed). The sheet aluminum shall have a nominal thickness of 0.05 in. (1.3 mm) and shall be according to ASTM B 209, Alloy 3003-H14 or better. The composite laminated aluminum shall have a nominal thickness of 0.080 in. (2.0 mm) with a nominal 0.01 in. (0.3 mm) aluminum skin on both sheet sides and shall have a minimum tensile strength of 4,300 psi at 73 °F (30,000 kPa at 23 °C). The sheet ABS plastic shall have a nominal thickness of 0.1 in. (2.5 mm) and shall have a minimum tensile strength of 4,300 psi at 73 °F (30,000 kPa at 23 °C). The vacuum formed ABS plastic backplate shall have a nominal thickness of 1/8 in. (3 mm), a nominal 1/2 in. (13 mm) deep back flange on all inside and outside edges, and a minimum tensile strength of 4,300 psi at 73 °F (30,000 kPa at 23 °C). The backplates shall be composed of one piece. The backplate shall be designed to be attached to a signal face without interfering with the opening and closing of the traffic signal door. It shall be rectangular in shape with round corners and shall be of such dimensions as to give an exposed margin of 5 in. (125 mm) on each side. The backplate shall have a 3 in. (75 mm) wide fluorescent yellow retroreflective strip applied to the outside perimeter of the face. Retroreflective sheeting shall be Type AZ sheeting according to Article 1091.03 and applied in the preferred orientation for the maximum angularity according to the manufacturer’s recommendations. Retroreflective sheeting shall be according to Section 1091. Where louvered backplates are specified, the surface of the louvered backplate shall provide openings (louvers) to allow wind to penetrate and reduce wind loading. The louver openings shall cover a minimum of 20 percent of the surface area of the backplate. Retroreflective sheeting shall not interfere with the louvers. The aluminum backplates shall be shop painted with one coat of primer and two coats of dull (matte) black enamel. The painting shall be according to Section 851. For the plastic backplates, the black color shall be an integral part of the material composition and shall not deteriorate under the exposure to ultraviolet sun rays.
1078.04 Directional Louver. The directional louver shall be made of aluminum
alloy and shall have a minimum of five vanes. The directional louver shall be shop painted with one coat of primer and two coats of dull (matte) black enamel. The painting and materials shall be according to Section 851. SECTION 1079. DETECTOR LOOP
1079.01 Inductive Loop Detector. The inductive loop detector shall be
according to the NEMA Standards for Traffic Control Systems, TS 2 and the following.
a.Functions. The inductive loop detector shall have a minimum of seven levels of sensitivity control and shall be of sufficient sensitivity to detect the smallest licensable motor vehicle, including motorbikes. Art. 1079.01 Detector Loop The inductive loop detector shall have a minimum of two modes of operation, presence or pulse. The inductive loop detector shall be capable of self tuning. The inductive loop detector shall, in a failure condition, register a continuous call to the signal controller. Extend Call – Delay Call. The inductive loop detector shall change from delay mode to extend mode and vice versa at the end of the time set for each mode. The inductive loop detector shall have a means of visually indicating the timings of delay and extension settings are in effect.
b.Special Feature. System Output. In addition to supplying normal timing output, the detector shall be capable of providing a simultaneous system output for traffic volume, occupancy, and speed measuring. The system output shall be constant and not affected by delay or extension timings. This output shall allow either presence or pulse operation which may be selectable from a front panel switch. The presence and pulse outputs shall be according to NEMA. When required, this feature shall be internal to the detector.
1079.02 Detector Loop and Sealer.
a.Wire. Detector loop wire is classified into three types as follows.
1.Type I detector loop wire and the loose encasing shall be according to IMSA 51-5.
2.Type II detector loop wire shall be No. 16 AWG, mineral-insulated, copper sheathed cable. The conductor shall be insulated with magnesium oxide and enclosed in a seamless copper sheath with a polyethylene jacket. A terminal subassembly kit composed of a pot, cap, sealer, and sleeves shall be supplied with the cable.
3.Type III detector loop wire shall be No. 14 or 16 AWG, Type THWN, THHN, or XHHW, with stranded copper conductor.
b.Preformed Detector Loop. The preformed detector loop shall be either of the following.
1.Rigid Plastic Conduit. The rigid plastic conduit shall be 5/8 in. (16 mm) outer diameter schedule 80 PVC or polypropylene conduit. All bends shall be a 6 in. (150 mm) radius minimum and shall be integral to the conduit.
2.Heavy Duty Reinforced Rubber Hose Conduit. The heavy duty reinforced rubber hose conduit shall be Class A oil resistant, hydraulic- type rubber hose reinforced with synthetic cord. It shall have an inner diameter of 3/8 in. (9.5 mm) and an internal pressure rating of 250 psi
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Source: Illinois Standard Specifications for Road and Bridge Construction, 2022 Edition. Pages 1044–1049 of 1,217. View official source ↗