Division 13-16-002
Signal Design Elements

Sections:

13-16-002-0001    Plan Set

13-16-002-0002    Intersection Design Requirements

13-16-002-0003    Traffic Signal Pole Design Requirements

13-16-002-0001 Plan Set

A.    For clarity of presentation and understanding, the plan set for a new traffic signal installation should contain the following sheets: the cover sheet, signal plan sheet, pole schedule sheet, conductor schedule sheet, civil plan sheet, signing and pavement markings sheets, and a detail sheet. The contents of the plan set may vary from this for projects involving modification of existing signals or where the new signal is included as a part of a larger construction project.

1.    The cover sheet shall meet the requirements of Section 13-06-002-0005, Cover Sheets.

2.    The traffic signal plan sheet (one (1) inch equals twenty (20) feet) shall show the signal-related details, such as: cabinets, poles, conduits, pull boxes, phasing indications, detection, and pavement markings. It shall include a foundation schedule and a pull box schedule. Both the foundation and pull box schedules shall include station and offset of the center of each foundation and pull box. Alternatively, dimensions from each roadway centerline may be used in lieu of station and offset. These schedules may be placed on a different sheet if necessary due to space limitations. The plan sheet should also show utility locations and existing, current, and future roadway construction, including dimensions from centerline to face of curb, to right-of-way, and to easements. Minor civil construction improvements may be included on this sheet. The plan sheet shall include general notes and notes for the signal construction.

3.    The pole and conductor schedule sheets shall each include a reduced scale intersection plan view to serve as an index to the schedules on these sheets. The reduced scale plan shall include curb lines, pavement markings, cabinets, poles, and conduits with their designations, and signal heads with their phasing.

4.    The pole schedule sheet shall also include separate phasing diagrams for the new signal, future phasing, if any, and preemption and other special programs. It shall also include the timing to be programmed for initial operation at start-up.

5.    The conductor schedule sheet shall include a table showing individual conduits and sizes; the cables, conductors or pull wires to be placed within each of them; notes relating to cable, conductor, and electrical service; and ADOT standard schedules for IMSA multi-conductor cables.

6.    The civil plan sheet(s) shall be provided to show, separate from traffic signal installation plan, the design of other elements included in the project. These elements include such work as replacement of curb or sidewalk, additional pavement for turn lane storage, drainage structures, relocations of existing improvements and utilities, and new sidewalk ramps.

7.    The signing and pavement markings sheet shall detail type, size, and location of all permanent and temporary signs and pavement markings and any additional information required to manage traffic safely at each phase of the construction.

8.    The detail sheet shall be used for any design and construction details that are unique to the particular project or are not included in the references standards and other documents.

B.    All drawings shall distinguish clearly between existing features, proposed construction with this project, and future construction or construction by others. (Ord. 2017-22, Rep&ReEn, 07/05/2017; Ord. 2020-10, Amended, 09/15/2020 (Res. 2020-13))

13-16-002-0002 Intersection Design Requirements

Refer to Division 13-10-006, Intersection Design, for geometric standards.

A.    Curb returns shall be constructed or reconstructed to provide dual ramps and minimum ten (10) foot spacing between signal poles in accordance with Standard Drawings 10-10-034 through 10-10-038.

B.    Signal equipment shall be located to accommodate anticipated future widening or additional approaches in order to minimize future modifications to the signal.

C.    Cabinets shall be located out of clear view zones for traffic at the intersection and at adjacent driveways.

1.    Consideration shall be given to locating cabinets and other signal equipment so as not to block driver view of adjacent, preexisting commercial advertising signs or businesses.

D.    The foundation for the traffic signal cabinet shall be oriented such that the door of the cabinet opens away from the intersection. A concrete technician’s maintenance pad, four (4) inches thick, four (4) feet wide, and the length of the cabinet foundation, shall be placed on the door side of the foundation. The elevation of the top of the pad shall be two (2) inches above adjacent curb for positive drainage. The cabinet foundation shall be four (4) inches higher than the technician’s maintenance pad.

E.    Signals shall be designed with an "8-pole" design; that is, two (2) signal poles on each corner of the intersecting streets.

1.    The minimum distance between the two (2) poles shall be ten (10) feet, in accordance with ADA and MUTCD requirements for separation of pedestrian detectors for different phases.

2.    Locations of all pedestrian detectors shall comply with MUTCD requirements.

3.    Additional pedestrian push-button poles shall be used when needed to meet MUTCD spacing and location requirements.

F.    Street lighting at the intersection shall be accommodated on combination signal poles rather than by the installation of separate streetlight poles.

1.    The number and location of luminaires vary with the size of the intersection, in accordance with Section 13-12-003-0002.3.

2.    Luminaires shall be installed on twenty (20) foot mast arms unless otherwise specified.

G.    Signal cabinets, traffic signal poles, pedestrian push-button poles, and streetlight poles shall be located outside of pedestrian and bicycle ways, including sidewalks, bikeways and bike lanes, FUTS trails, accessible routes, or curb ramps, so that the full width of these facilities is maintained and not narrowed. Refer to City of Flagstaff Engineering Detail 16-02-010 for pedestrian push-button locations.

H.    All poles having a pedestrian push-button station shall be located adjacent to a sidewalk or sidewalk ramp, or shall have an access pad installed to meet the requirements of the Americans with Disabilities Act. Reach distance to push-button stations shall not exceed ten (10) inches.

I.    Each pole foundation shall be provided with a one-half (1/2) inch PVC drain to allow water to drain from the pole adjusting-nut sump.

J.    Overhead left turn signal heads shall be twelve (12) inches – four (4) section heads, unless protected-only phasing, when (12) inches – three (3) section heads shall be utilized.

K.    Side of pole-mounted left or right turn signal heads shall be twelve (12) inches – four (4) section heads, each installed on an individual Type V mount and shall be mounted as low as possible, adhering to MUTCD visibility and clearance standards and guidance.

L.    Pole top-mounted right or left turn signal heads shall be twelve (12) inches – four (4) section heads. These may be mounted on a combination mount with one (1) other signal head.

M.    All signal heads shall include a one (1) inch fluorescent yellow prismatic retroreflective border around the entire perimeter of the backplate.

N.    Mast arm-mounted signal heads shall be centered over each traffic lane.

O.    Seven (7) conductor IMSA cable shall be run to each left turn signal head. Where left turn signals are not included in the initial construction, a seven (7) conductor IMSA cable shall be run to each far left signal head, and to the signal head at the far outboard end of the mast arm on all approaches. Where future dual left turn lanes are expected, an additional seven (7) conductor IMSA cable shall be run to the second-to-last outboard mast arm tenon. A seven (7) conductor IMSA cable shall also be run to each right turn signal head.

P.    A separate four (4) conductor IMSA cable shall be run to each inboard mast arm signal head, right side-mounted signal head (except for right turn signal heads), each pedestrian signal head, and each pedestrian push button.

Q.    The intersection will be "boxed" with two (2) three (3) inch diameter conduits.

1.    One (1) conduit shall contain higher voltage signal and lighting conductors.

2.    The second conduit shall contain lower voltage detection, preemption and communications conductors.

R.    All splicing will occur in the No. 7 pull boxes.

S.    When the intersection lies along the path of a future fiber-optic interconnect route, two (2) additional four (4) inch conduits, each with a No. 8 green THW pull wire, shall be installed along that route throughout the project limits. Interconnect conduit shall be schedule 40 PVC or SDR 11 HDPE, unless otherwise approved by the City Traffic Engineer. Interconnect pull boxes shall not be placed in sidewalk areas when possible, but behind sidewalks or in greenways to minimize tripping hazards.

1.    Interconnect pull boxes shall be installed no more than one thousand three hundred twenty (1,320) feet apart and shall be COF No. 9 per City of Flagstaff Engineering Detail 16-03-010.

2.    A dedicated interconnect pull box shall be installed adjacent to a traffic signal pull box at intersections, preferably on the same corner as the signal control cabinet.

3.    A three (3) inch conduit shall be installed to the traffic signal cabinet from the closest interconnect pull box.

4.    Ninety (90) degree elbows are not to be used with the fiber-optic interconnect conduit unless specifically approved by the City Traffic Engineer. Where ninety (90) degree bends are necessary, they are to be made up of a series of forty-five (45) degree or less elbows, with a minimum radius of twenty-four (24) inches.

5.    A maximum of three hundred sixty (360) degrees of cumulative bends between pull boxes is allowed, including both horizontal and vertical bends. Install additional No. 9 pull boxes if necessary to meet this requirement.

T.    All trenches in existing pavement shall be slurry backfilled and T-topped.

U.    A minimum of one (1) No. 7 pull box, with extension, shall be installed on each corner of the intersection.

V.    Controller operation shall be NEMA dual ring. Phase 2 shall be used for the main street through movement, either the eastbound or northbound direction.

W.    Flashing mode shall be all red. (Ord. 2017-22, Rep&ReEn, 07/05/2017; Ord. 2020-10, Amended, 09/15/2020 (Res. 2020-13); Ord. 2024-13, Amended, 4/16/2024 (Res. 2024-15))

13-16-002-0003 Traffic Signal Pole Design Requirements

This section describes the general requirements for traffic signal equipment to be installed within, or supplied to, the City of Flagstaff.

A.    General Requirements. All traffic signals and lighting equipment shall comply with the Arizona Department of Transportation, Standard Specifications for Road and Bridge Construction (current revision) and the Arizona Department of Transportation, Traffic Signals and Lighting, Standard Drawings (current revision), in addition to meeting the requirements of this specification. If there are any differences, City of Flagstaff standard details and specifications will supersede Arizona Department of Transportation.

B.    Traffic Signal Structure.

1.    A traffic signal structure is a complete pole and mast arm assembly attached to a concrete foundation. The traffic signal structure consists at a minimum of:

a.    Pole;

b.    Signal mast arm;

c.    Luminaire mast arm;

d.    Foundation anchor bolts;

e.    Mast arm connecting hardware;

f.    Signal tenons;

g.    Vibration device;

h.    Top cap hardware;

i.    Pole hardware including hand hole covers;

j.    Concrete foundation with steel reinforcing (where required).

2.    Traffic signal structures shall be supplied per City of Flagstaff standard detail 16-02-020.

3.    Each signal mast arm shall include a dynamic vibration mitigation device. The dynamic vibration device shall meet the following specification:

a.    The dynamic vibration mitigation device shall aesthetically fit behind a three (3) section signal head and not accumulate dirt or snow buildup. It shall be an active, nonaerodynamic vibration damper system to effectively mitigate the vertical movement under fatigue loads. The pole manufacturer will be required to submit all the necessary documentation and independent third-party testing of the device to prove the device is greater than eighty-five percent (85%) or greater excitation reduction for the entire range of structures in the standard. The device shall be robust to dampening large displacements and small displacements and be self-adapting, not requiring structure-specific tuning. The mitigation device shall be tested to withstand over seventeen million (17,000,000) large amplitude cycles with no deterioration of the dampening performance. (Ord. 2024-13, Enacted, 4/16/2024 (Res. 2024-15))