Departmental Material Specifications
DMS-11120, Vehicle Signal Heads
DMS-11120, Vehicle Signal Heads
Overview
Effective Dates: August 2004–March 2008.
This Specification governs for the materials, composition, quality, sampling, and testing of
traffic control signal heads.
Bidders’ and Suppliers’ Requirements
To be accepted on bids, materials must have approved product codes or designations and be
from prequalified producers. The Traffic Operations Division (TRF) of the Texas
Department of Transportation (TxDOT) maintains the material producers list of approved
producer product codes or designations. For more information on these materials, please
contact Henry Wickes at 512/506-5125.
Use of prequalified materials does not relieve the contractor of the responsibility to provide
materials that meet the specifications. All material may be inspected or tested at any time.
Any material that does not meet the specifications and requirements of the plans will be
rejected.
Prequalification
Submit a sample 3-section signal head including optical units to the Texas Department of
Transportation, Traffic Operations Division, 9500 Lake Creek Parkway, Austin, Texas
78717 for evaluation.
Provide additional samples when directed by the Department.
The Traffic Operations Division (TRF) tests samples for specification compliance and
updates the list to include materials that meet specification requirements.
If materials fail to meet any of the specification requirements, the producer may not
resubmit for prequalification until 1 yr. from original evaluation date. TRF may waive this
time limit if provided with documentation from an independent testing facility stating the
materials meet all requirements. TRF will enforce the 1-yr. time limit if, after retesting, the
material again fails any of the specification requirements.
Prequalified material provided on a project that does not match the prequalified sample will
result in the removal of that manufacturer from the prequalified list for 1 yr. at the discretion
of the Department.
All materials submitted for prequalification tests will be at no cost to the Department.
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Departmental Material Specifications
DMS-11120, Vehicle Signal Heads
Procurement and Payment
Payment for all materials under this Specification will be in conformance with provisions of
the purchase order awarded by the Department or the conditions prescribed in the contract
awarded by the Department.
Sampling and Testing
Specific tests are normally indicated in conjunction with specific specification requirements.
However, the Department reserves the right to conduct whatever tests are deemed necessary
to identify component materials and verify results of specific tests indicated in conjunction
with specification requirements.
Costs of sampling and testing are normally borne by the Department; however, the costs of
sampling and testing materials failing to conform to the requirements of this Specification
are borne by the contractor or supplier. This cost will be assessed at the rate established by
the Director of TRF and in effect at the time of testing.
Amounts due to the Department will be deducted from monthly or final estimates on
contracts or from partial or final payments on direct purchases by the Department.
Any deviation in product design after testing and approval from TxDOT constitutes a new
model, which must be resubmitted for acceptance. Failure to notify the Department of the
change and resubmit for approval is grounds for removal from the Department’s Qualified
Product List (QPL) for an undetermined time.
Material Requirements
General
Except where noted herein, provide traffic control signal heads in accordance with the latest
revisions of both of the following:
♦ Equipment and Material Standards of the Institute of Transportation Engineers, Chapter
2: “Vehicle Traffic Control Signal Heads”
♦ Texas Manual on Uniform Traffic Control Devices.
The procurement or Contract specifies both of the following:
♦ material – aluminum or polycarbonate
♦ light source – incandescent optical unit, LED modules, or none.
Definitions
Incandescent Optical Unit – lens, reflector, lamp, lamp receptacle, and associated supporting
parts.
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Departmental Material Specifications
DMS-11120, Vehicle Signal Heads
LED Module – an array of light emitting diodes sealed in its own lens and housing that is
capable of providing a traffic signal indication.
Signal Section – the assembly of a signal housing case, housing door, visor, and an optical
unit or LED module.
Signal Face – the front part of a signal head.
Signal Head – 1 or more signal faces that when illuminated in a definite sequence indicate to
traffic approaching the signal face the right of way at the intersection or give warning of
existence of a hazardous condition. When designated as 2-way, 3-way, 4-way, or 5-way
signal head, that number of faces are attached to pipe-arm supports (e.g., a 3-way signal
head requires 3 signal faces). Unless otherwise specified, the pipe support arms radiate from
their point of support at equal angles (i.e., 180°, 120°, 90°, and 72° angles of separation for
2-way, 3-way, 4-way, and 5-way signal heads, respectively).
Physical and Mechanical Requirements
Provide signal head and components, including optical unit, LED module, and mounting
attachments that meet the following requirements:
♦ new
♦ accurately formed
♦ free of defects affecting strength and appearance
♦ adequate in strength for the purpose intended
♦ corrosion- and rust-resistant (capable of withstanding constant exposure to corrosive
atmospheres, including salt air)
♦ UV- and color-stabilized (capable of withstanding constant exposure to sunlight) and
♦ operates reliably throughout an ambient temperature range of −40°F to 165°F.
This above temperature range corresponds to the environmental tests required by the
National Electrical Manufactures Association Standards Publication TS-2-1998 – Traffic
Controller Assemblies with NTCIP Requirements. The Department may use the
environmental testing required by TS-2-1998 while qualifying signal heads and their
components.
Join individual signal sections to form a single rigid “signal face” with a minimum of 3
machine screws (with nut, 2 flat washers, and lock washer) connecting each section.
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Departmental Material Specifications
DMS-11120, Vehicle Signal Heads
The maximum allowable vertical deflections at the point of loading for a horizontally
mounted 3-section signal head are 3.00 and 5.00 in. for a 2- and 10-lb. applied load,
respectively. For this test, use standard 1-1/2-in. pipe signal mounting fittings to clamp the
end of the signal head (without the backplate and visors) against a rigid vertical surface with
the signal face oriented so that the maximum deflection possible will occur (usually face
up), apply a vertical load at the opposite end, and measure the deflection at the point of
loading.
Provide aluminum parts conforming to the applicable specifications in the following table,
“Referenced Specifications for Aluminum.” Cast aluminum parts must be accurately formed
and free from pouring faults, sponginess, cracks, blow holes, or other defects affecting their
strength and appearance.
Referenced Specifications for Aluminum
Type
ASTM
Alloy
Minimum Tensile Strength
SG100B, SG100A, SC84B,
17,000 psi
Die Castings
B85
SC84A, S12B, or SC12A
Permanent Mold Castings
B108
CS72A or S5A
17,000 psi
Sheet
B209
M1A
27,000 psi
Provide polycarbonate parts:
♦ ultraviolet- (UV) and color-stabilized
♦ one-piece, molded construction
♦ minimum of 0.090 in. thick and
♦ meet the physical property requirements and specifications in the following table,
“Requirements & Referenced Specifications for Polycarbonate.”
Requirements & Referenced Specifications for Polycarbonate
Test
Required
ASTM
Specific Gravity
D792
≥ 1.17
Vicat Softening Point
305 – 325°F
D1525
Brittleness Point
D746
< − 200°F
Flammability
Self-Extinguishing
D635
Tensile Strength (Yield)
D638
≥ 8500 psi
Elongation at Yield
5.5 to 8.5 %
D638
Shear Strength (Yield)
D732
≥ 5500 psi
Izod Impact Strength (notched, 1/8 in. thick)
D256
≥ 15 ft-lb/in
Fatigue strength, (2.5 mm cycles)
D671
≥ 900 psi
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Departmental Material Specifications
DMS-11120, Vehicle Signal Heads
Provide bolts, nuts, washers, lock washers, screws, and other assembly hardware fabricated
of galvanized steel, stainless steel, or dichromate-sealed aluminum according to the
specifications in the following table, “Referenced Specifications for Hardware.”
Material
Stainless Steel
Galvanized Steel
Aluminum
Brass
Referenced Specifications for Hardware
Applicable Specification
ASTM A 320, Grade B8F Annealed
ASTM A 307 Galvanized to either:
♦ ASTM A 153, Class C or D
♦ ASTM B 695, Class 50.
Alloy 2024-T4 dichromate sealed finished according to Mil-A-8625A Type II
UNS C36000
When dissimilar metals are used, select or insulate in a manner that prevents corrosion.
Use fiberglass reinforced polycarbonate for all non-metallic hardware.
In the incandescent optical unit, use closed-cell silicone or peroxide-cured EPDM as a
gasket material that is rated to withstand temperatures up to 250°F without becoming brittle
or deforming permanently.
For gaskets outside the incandescent optical unit, use closed-cell neoprene.
Housings, Doors, and Visors
Design door, housing, and visor so that when assembled:
♦ light is emitted only through the lens and
♦ the head (with mounting attachments and incandescent optical unit or LED module) is
dust and moisture proof.
Provide housing, doors, and visors of like material (aluminum or polycarbonate).
Seal unused holes at the ends of assembled signal heads with removable nylon plugs to
prevent the entry of foreign material (e.g., dust, insects, and moisture) into the housing.
Provide housings of the sectional adjustable expandable type with the following features:
♦ 1-piece construction
♦ die-cast aluminum alloy, permanent mold-cast aluminum alloy, or molded polycarbonate
♦ large integrally molded bosses where supporting arms are to be attached
♦ one 2-in. diameter opening in both the top and the bottom of each housing to
accommodate 1-1/2-in. pipe brackets
♦ a minimum of 4 holes for mounting a back plate on the rear of each signal section that
do open to the inside of the housing and accommodate No. 8 × 1/2-in. self-threading
screws
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DMS-11120, Vehicle Signal Heads
♦ capability of being rotated 360° about its mounting axis and locked at 5° intervals by the
engagement of integral serrations in adjacent signal sections and in the mounting bracket
assembly
♦ interchangeable individual sections.
Provide doors of the same material as the housing with the following features:
♦ two captive thumb screws (with flat-bearing surface or washer) on the side of the door to
allow opening and closing the door without special tools
♦ hinges that hold the door in perfect alignment when closed
♦ two stainless-steel or integrally molded reinforced polycarbonate hinge pins.
Provide a standard tunnel type visor that:
♦ is easily detachable
♦ prevents light and moisture leak where attached to door
♦ is circular in section
♦ has a downward tilt of 2° to 8° relative to the perpendicular to the plane of the housing
door
♦ encompasses approximately 300° of the lens
♦ extends outward from the face of the lens a minimum of 9-1/2 in.
♦ is open at the bottom so as to prevent the accumulation of snow and dirt
♦ has minimum thickness of:
•
0.050 in. for cast or sheet aluminum alloy
•
0.100 in. for polycarbonate visors.
Exterior Finish
The color of the completed traffic signal, with the exception of the insides of the visors,
must be Federal Yellow No. 13538 of Federal Standard 595, unless stated otherwise in the
procurement or Contract.
Paint all exposed metal surfaces, except the inside of the visors, with electrostatically
applied powder-coat paint or 2 separately applied baked-on coats of high-grade enamel.
Completely impregnate the specified colorant in the polycarbonate material.
Paint the inside of the visors with 2 coats of high-grade flat-black finish paint.
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Departmental Material Specifications
DMS-11120, Vehicle Signal Heads
Incandescent Optical Unit
Do not provide incandescent optical units unless indicated in the procurement or Contract.
Do not provide lamps unless indicated in the procurement or Contract.
Design incandescent optical unit to operate at a nominal operating voltage of 117 V RMS
from a single-phase, 60 Hz alternating current power supply.
Each optical unit consists of a lens, a reflector, and a lamp receptacle with leads to the
terminal block (which is to be furnished in each complete traffic signal face assembly)
together with all bolts, nuts, screws, clips, hinges, lugs, and incidentals necessary for
mounting and sealing the various parts of the optical assembly.
Optical systems must be capable of withstanding continuous illumination of a 150 watt lamp
in a 12-in. head without distortion. Provide injection-molded polycarbonate lenses. Glass
lenses with a high transmission value and a minimum specific gravity of 2.50 may also be
substituted for polycarbonate lenses on aluminum traffic signal heads.
Permanently mark lenses with the trademark of the manufacturer and an indication
providing the proper lens orientation.
Provide reflectors that are approximately parabolic in section; made of silvered glass,
aluminum with anodic coating, or metalized plastic; and are totally free of flaws, scratches,
defacements, or mechanical distortion.
Rigidly attach reflector to the head with hinges or lugs in a manner that allows it to be easily
removed from the head but does not require its removal for relamping or cleaning.
When glass reflectors are provided, apply the silver so that there is no inclusion of foreign
substances between the silver and glass and place a heat-resisting backing of high-grade
enamel over the copper coating.
Provide lamp receptacles that:
♦ of weather-proof molded construction
♦ have 2 captive 3-ft. long leads of 18 AWG wire conforming to the National Electric
Code with insulation rated for service at 600 V at 105°C and color coded as required by
the table on "Wire Color Codes”
♦ will not deteriorate due to the high temperatures occurring within the optical unit during
operation
♦ have brass contact and threads that provide uniform and sufficient electrical connection
between lamp and receptacle
♦ have a lamp grip to prevent the lamp from loosening due to vibration
♦ are rotatable to allow proper lamp filament orientation
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DMS-11120, Vehicle Signal Heads
♦ will place the filament of a standard 150 watt traffic signal lamp (A21 Bulb with a
medium base and a 3 in. light center length) in the proper focal position with respect to
the reflector.
LED Traffic Signal Module
Do not provide LED traffic signal modules unless indicated in the procurement or Contract.
An LED traffic signal lamp unit is comprised of a UV- and color-stabilized polymeric outer
shell, multiple LED light sources, and a regulated power supply.
Failure of LED traffic signal module power supply or any of its components must occur in a
safe manner. It is not acceptable for LEDs to remain illuminated, even dimly, after the AC
circuit feeding the LED traffic signal module is de-energized.
The use aluminum-gallium-arsenic (AlGaS) LEDs in traffic signals is not allowed, because
of unacceptable temperature-related degradation.
Provide LED traffic signal modules that:
♦ are operationally compatible with TS1, TS2, 170, and 2070 controllers, conflict monitors
with plus features, and malfunction management units currently used by the Department
and any other Texas government entities whose specifications and requirements do not
conflict with the Department’s
♦ present a “catastrophic LED failure” impedance of at least 500,000 ohms to the AC line
upon sensing a loss of between 25% and 40% of the initial light output
♦ operate without flickering on a 60 Hz AC line voltage ranging from 80 to 135 V RMS
♦ operate with a minimum 0.90 power factor
♦ do not induce greater than 20% total harmonic distortion (current and voltage) into an
AC power line
♦ conform to Federal Communications Commission (FCC) Title 47, SubPart B, Section 15
regulations concerning the emission of electronic noise
♦ have no less than 5 equally loaded circuits (i.e., strings) of LEDs
♦ have power supplies that provide protection and regulated, capacitor-filtered DC current
to the LEDs within the limits recommended by LED manufacturer
♦ have 2 captive 3-ft. long leads of 18 AWG wire conforming to the National Electric
Code with insulation rated for service at 600 V at 105°C and color coded as required by
the table on "Wire Color Codes”
♦ are self-contained devices, interchangeable with standard incandescent optical units
♦ require no modifications to the signal housing or door
♦ have indication showing the proper lens orientation when required for optimum
performance
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DMS-11120, Vehicle Signal Heads
♦ are permanently marked with manufacturer's name, serial number, manufacture date
(month and year) and other necessary identification
♦ are labeled certifying compliance to applicable ITE standards
♦ are tolerant to mechanical shocks and vibrations due to foreseeable events such as
transporting, shipping, or high winds
♦ are rated for use in the ambient operating temperature range of −40°C to +74°C
♦ have watertight enclosures meeting the requirements of a Type 4 according to NEMA
Standard 250-1991
♦ have aluminum-indium-gallium-phosphide (AlInGaP) LEDs (or other LEDs less
susceptible to temperature degradation than AlGaS LEDs) mounted at evenly spaced
intervals across the illuminated portion (i.e., filled-in, not outlined) of the polycarbonate
positioning plate or conformally-coated PC board
♦ have arrow indications tested in conformance with California Test 3001
♦ have minimum laboratory light intensity, color (chromaticity), and light output
distribution values as described in Equipment and Material Standards of the Institute of
Transportation Engineers, Chapter 2: “Vehicle Traffic Control Signal Heads” (VTCSH),
excepted as noted in the “Minimum Initial Luminous Intensity Values” table and the
'Chromaticity Standards' table of this Specification.
Minimum Initial Luminous Intensity Values
Circular Indication
Arrow Indication
Vertical
Angle
±2.5°
±7.5°
±12.5°
±17.5°
Horizontal
Red
Angle
(Candelas)
(°Left/°Right)
2.5°
339
7.5°
251
12.5°
141
17.5°
77
2.5°
226
7.5°
202
12.5°
145
17.5°
89
22.5°
38
27.5°
16
2.5°
50
7.5°
48
12.5°
44
17.5°
34
22.5°
22
27.5°
16
2.5°
22
7.5°
22
12.5°
22
Texas Department of Transportation
Yellow
(Candelas)
678
501
283
154
452
404
291
178
77
32
101
97
89
69
44
32
44
44
44
Green
Red
Yellow
(Candelas) (Candelas) (Candelas)
678
501
283
154
452
404
291
178
77
32
101
97
89
69
44
32
44
44
44
9
54
40
29
21
44
32
23
17
12
9
17
12
9
7
5
4
6
5
3
135
99
72
53
109
80
59
43
31
23
43
31
23
17
12
9
16
12
9
Green
(Candelas)
70
51
38
27
57
42
30
22
16
12
22
16
12
9
6
5
8
6
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Departmental Material Specifications
DMS-11120, Vehicle Signal Heads
17.5°
22
44
44
2
6
3
22.5°
20
41
41
2
5
2
27.5°
16
32
32
1
3
2
2.5°
20
40
40
–
–
–
±22.5°
17.5°
20
40
40
–
–
–
2.5°
20
40
40
–
–
–
−27.5°
17.5°
20
40
40
–
–
–
2.5°
20
40
40
–
–
–
−32.5°
17.5°
20
40
40
–
–
–
This table replaces the values in Table 1 of Section 4.1.1 of the I.T.E. VTCSH.
The 6.4.2.1 test must include an expanded view for the Red and Green Ball indications with the above
minimums for a period of 60 months, based on normal use in traffic signal operation over an operating
temperature range of 25°C.
During production, “burn-in” each LED traffic signal lamp at an ambient temperature of
60°C and a nominal operating voltage of 117 V RMS for a minimum of 24 hr. so that
electronic-component reliability is demonstrated and any electronic infant mortality occurs
prior to shipment.
After burn-in, measure and record the luminous intensity and chromaticity of each module
along with the current, voltage, total harmonic distortion (THD), and power factor (PF) at an
ambient temperature of 25°C and a nominal operating voltage of 117 V RMS. Take
measurements for yellow LED signal modules immediately after the modules are energized.
Take measurements for other LED signal modules after modules have been energized
continuously for 30 min.
Chromaticity Standards
Red
Yellow
Green
(0.998 − x ) ≤ y ≤ 0.308
0.411
and
0.995 − x
(
⎫⎪
⎬≤
)⎪⎭
y ≤ 0.0.452
(0.506 − 0.519 x )⎫⎪
and
⎬≤
(0.150 + 1.068 x )⎪⎭
(
y ≤ 0.730 − x
)
Measured chromaticity coordinates of LED signal modules must
conform to the chromaticity requirements of this table, for a
minimum of 60 months, over an operating temperature range of
−40˚F to +165˚F. Each LED traffic signal lamp unit must meet the
minimum requirements for light output for the entire range from 80
to 135 V.
Provide the following LED traffic signal module documentation with each signal head:
♦ complete and accurate installation instructions
♦ warranty repair contact information (name, address, and telephone number of
representative, manufacturer, or distributor)
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DMS-11120, Vehicle Signal Heads
♦ schematic diagrams for all electronics (when requested)
♦ individual LED manufacturer info (name, brand, and model number), along with the
LED manufacturer’s recommended drive current and degradation curves
♦ test report from an independent laboratory certifying the LED traffic signal lamp meets
I.T.E. Standards for light distribution, chromaticity, and power (consumption, power
factor, and harmonic distortion) with the 'Minimum Initial Luminous Intensity Values'
table and the 'Chromaticity Standards' table of this specification replacing the
corresponding tables of the I.T.E. VTCSH and that the drive current supplied to
individual LEDs within the unit do not exceed the LED manufacturer’s
recommendations (i.e., the LEDs are not overdriven).
Provide a written warranty from the manufacture of the LED traffic signal modules
guaranteeing that, during the first 60 months of continuous use over the temperature range of
−40°C to +74°C, the LED traffic signal module will:
♦ not fail due to workmanship or material defects
♦ initially meet and then not fall below specified minimum initial luminous intensity
values given in the table on “Minimum Initial Luminous Intensity Values”
♦ meet the chromaticity standards given in and the table on “Chromaticity Standards”
♦ be replaced by manufacturer within 5 business days following receipt of failed module
with no costs to the Department other than those for shipping failed modules.
The Department may perform random sample testing on shipments of LED modules already
on the Department’s prequalified list within 30 days after delivery with the sample size,
acceptance, and rejection conforming to ANSI/ASQC Z1.4. The quantity of each model
received determines the sample size. LED signal modules tested or submitted for testing
must be representative of typical production units.
The Traffic Operations Division will determine the sampling and testing parameters to be
used. The Department may test supplied LEDs to the requirements of this specification
using any appropriate tests including the following:
♦ destructive “clip-out” testing of the “fail-safe” circuit to catastrophic LED failure
♦ destructive “drive-current” testing to assure individual LEDs are not driven beyond the
LED manufacturers recommendations
♦ submersion testing to determine water-tightness
♦ luminous-intensity testing
♦ chromaticity testing.
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DMS-11120, Vehicle Signal Heads
Electrical
Provide 1 “housing” terminal block in each individual signal housing section for connecting
light source electrical leads to the interior signal head wiring and 1 separate “assembly”
terminal block in the terminal (i.e., green indication, bottom, or right) housing section to
connect the interior signal head wiring to the field wiring. Provide terminal blocks with the
following features:
♦ six-section, double-row with each section consisting of two 8-32 × 5/16-in. binding
screws and a conducting metal strip between the screws
♦ one-piece molded construction using phenolic materials
♦ weatherproof molded construction
♦ securely mounted or integrally molded in an accessible location
♦ rated for a minimum 20 amps, 250 V service
♦ minimum 1600 V AC RMS section-to-section breakdown voltage
♦ nickel-plated brass used for all metal parts with the exception of the screws, which may
be nickel-plated brass or stainless steel.
Use and maintain throughout the traffic signal head the color coding shown in the following
table for wires from the lamp holder or LED module to assembly terminal block in the
terminal housing.
Wire Color Codes
Indication
Color Code
Red Ball / Arrow
Red
Yellow Ball
Yellow
Green Ball
Brown
Yellow Arrow
Yellow With Blue Or White Tracer
Green Arrow
Brown With Blue Or White Tracer
Neutral
White
Completely wire the signal head assembly so that installation only requires attaching the
field wires at the assembly terminal block.
Wire the signal head so that any indication can be individually illuminated through
connections to terminals on the assembly terminal block in the terminal housing. Bring 1
color-coded hot conductor (see 'Wire Color Codes' table) from each housing terminal block
to the assembly terminal block and connect each to a separate section on the assembly
terminal block. Bring a neutral conductor from each housing terminal block to each adjacent
terminal block and finally to an empty section on the assembly terminal block.
When an incandescent optical unit or LED module is provided, connect its leads to the
appropriate terminal of its housing terminal block in its corresponding signal housing
section using solderless wire connectors or binding screws and spade lugs.
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DMS-11120, Vehicle Signal Heads
The procurement or Contract will specify any variations from the above electrical
requirements.
Mounting Requirements
The Contract or procurement specifies mounting attachments — span-wire, side-of-pole,
top-of-post, mast-arm, or none — to be provided with the signal head.
Except where specifically changed by the Contract or procurement, provide mounting
attachments with the following basic features:
♦ provision for each housing to be rotated independently about its attachment axis in
increments of 15° or less and positively clamped into position by the engaging of radial
serrations on the housings and fittings
♦ signal cables carried through the mounting attachment so that they are fully enclosed and
protected
♦ attachment seals the completed signal head to create dust-proof, moisture-proof
enclosure
♦ aesthetically pleasing plug sealing unused openings in assembled signal head and
attachments.
Provide span-wire mounting attachments with the following features:
♦ a cable clamp to receive a suspension cable of 3/8-in. diameter with a suitable
connection to the signal head
♦ a balance adjuster between the signal head and the span wire capable permitting freedom
of movement with reference to the point of suspension
♦ ability to be rotated about the vertical axis and securely clamped at any position
throughout the range of adjustment
♦ a weather head or other suitable method for taking signal cables into the signal head that
effectively prevents abrasion of the signal wiring and the entrance of dust and moisture
into the head
♦ prebalanced or balanceable around the point of attachment so that the head will hang
plumb.
For side-of-pole mounting attachments provide standard pipe-arm brackets, attached to the
top and bottom of the signal head, extending 12-3/4 in. from and at right angles to the axis
of rotational adjustment, and at least 1-1/4 in. of thread at the pole connection end.
For top-of-post mounting attachments provide standard pipe-arm brackets, attached to the
top and bottom of the signal head and connected to a slipfitter as either the hub or as part of
the hub of the bottom pipe-arm assembly. The slipfitter requirements:
♦ fits a 4-1/2-in. outside diameter pipe
♦ pleasing in appearance
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DMS-11120, Vehicle Signal Heads
♦ adequate in strength (i.e., capable of holding the signal head rigidly in place)
♦ attaches to the pole with six 3/8-20 stainless-steel set screws set in pairs with a 120°
spacing
♦ effectively seals the interior of the pipe from moisture.
When mast-arm mounting is specified, the Contract or procurement will provide detailed
information concerning the attachment to be provided.
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