9-158 Section 919. Permanent Traffic Sign and Support Materials
919.01 General Requirements
Permanent traffic signs and sign support material must meet the requirements of the MDOT Sign Support Standard Plans and this section.
919.02 Traffic Signs
The Department classifies signs by type of sign panel material and type of sign face, as follows: Table 919- 1: Sign Panel and Face Types Sign Panel Type Material Size Limits I Aluminum extruded s ections Height >48 inch es or width >120 inches II Plywood Height = 48 inch es and width = 24 inches Minimum height ≥36 inches and width ≥36 inches Maximum height ≤48 inches and width ≤120 inches III 0.080 in ch aluminum s heet(a) 36 by 36 in ches IV 0.040 inch aluminum s heet(a) Overlay V 0.125 inch aluminum s heet(a) 48 by 48 inch es and as shown in MDOT’s SIGN -100 s eries Sign Face Type Background Legend and Border A Reflectorized Reflectorized B Reflectorized Non-reflectorized C Non-reflectorized Reflectorized
a.Round the corners and remove burrs at the corners and mounting holes .
A.Sign Panel Material and Fabrication
1.Aluminum Extruded Sections . Provide aluminum extruded sections in a variety of widths with plain butt -type edges for connecting to adjoining horizontal sections . Sections must be one piece with no vertical splices and have a cross-sectional shape meeting the minimum requirements specified in Table 919 -2. Sections must have at least a 0.125-inch nominal thickness . Exterior corners must have a radius of at least 0.040 inch. Sign panel sections must be extruded aluminum alloy 6063- T6 meeting the requirements of ASTM B221. Panel sections, after MDOT Standard Specifications for Construction Section 919 9-159 fabrication, must be flat to within 0.031 inch or less per foot of length and to within 0.004 inch or less per inch of widt h. Table 919- 2: Cross- Sectional Requirements for Aluminum Extruded Sign Sections for Type I Sign Panels Length of Sign Support Type Moment of Inertia Section Modulus Elements of Cross Section No Free Ends One Free End b/t ≥I/y b/t ≥I/y ≤30 f eet on c olumns ≤20 f eet on c antilevers ≤30 f eet on t russes ≥0.94 W ≥0.55 W 8–50 56.0C 5–28 32.0A >50 3.4D >28 11.6B Note s: b = compression width of stiffener elements in inches t = thickness of the stiffener element in inches I = moment of inertia of the sign section in inches y = distance from the neutral axis to the centroid of the compression width of the element W = width of the sign section in feet A = W/(63 -b/t) B = 1.0 × 10−4 W(b/t)² C = W/(111 -b/t). D = 1.0 × 10−4 W(b/t)² Degrease aluminum extruded sign panel sections in accordance with the sheeting manufacturer ’s recommendations . After degreasing, surface treating, and rinsing, maintain sign panels free of grease, oil, or other contaminants. Connect the sections horizontally with ⅜ -inch diameter stainless steel bolts, spaced as shown on the MDOT Sign Support Standard Plans . Section connections or sign-to -post connections must have no fasteners that project through the sign panel face. Position the plank second from the bottom of the sign. Position the 6-inch panel between two 12-inch panel sections. Do not use 6-inch panels for the signs top or bottom. Before transporting sign panels, ensure that the support angles and wide flanged shapes are shop connected and remain on the sign.
2.Plywood . Plywood sign panels must be ⅝ -inch thick and have a black or natural color overlay on both sides . Panels must meet the requirements of the U.S. Product Standard PS1-09 for Group 1 wood species, Grade B -B veneer, exterior type, high-density overlaid plywood. Inner plies must meet the requirements of Section 5 .8.1, “Crossband Gaps and Center Gaps ,” of the U.S. Product Standard PS1-09. Inner plies must have no continuous core gaps, tunnels, MDOT Standard Specifications for Construction Section 919 9-160 holes, or through openings that travel longitudinally or transversely through the plies, as measured from the panel edge. Crossband gaps or center gaps allowed by the U.S. Product Standard PS 1-09 must be filled with a synthetic filler repair in accordance with Section 5 .3, “Synthetic Repairs ,” of the U.S. Product Standard PS 1-09. Do not make vertical splices in plywood signs . The Engineer will allow horizontal splices only for e xit gore signs . Do not splice plywood sign panels unless otherwise shown on the sign details . Do not make horizontal splices through le gends or symbols. Prepare the plywood surface for sheeting application by lightly abrading the surface with a product recommended by the sheeting supplier . Do not power sand. Wipe the surface with a solvent and allow to dry in accordance with the sheeting manufacturer ’s recommendations . Smooth and seal edges with one coat of exterior oil base paint. After preparing the plywood surfac e, ensure that no grease, oil, or other contaminants come into contact with the surface.
3.Aluminum Sheet . Provide a luminum sheet for Type III , Type IV , and Type V sign panels meet ing the requirements of ASTM B209 for aluminum alloy 6061-T6, 5052 -H38, or 5154- H38. Aluminum sheet for Type III sign panels must be fabricated from nominal 0.080- inch-thick aluminum sheet wit h mill tolerance meeting the requirements of ASTM B209. Aluminum sheet for Type IV overlay sign panels must be fabricated from at least nominal 0.040- inch-thick aluminum sheet at least 0.037 inch thick. Degrease the aluminum sheet in accordance with the sheeting manufacturer ’s recommendations . After degreasing, surface treating, and rinsing, maintain sign panels free of grease, oil, and other contaminants.
B.Sign Face and Legend Material
1.Reflective Sheeting Material . Select reflective sheeting for permanent s igns from the Qualified Products List. Provide the Engineer with written certification that reflective sheeting meets the following requirements:
a.Sheeting material on each sign is a Qualified Product obtained from the same sheeting manufacturer;
b.Signs are manufactured in strict compliance with the sheeting manufacturer ’s requirements; and MDOT Standard Specifications for Construction Section 919 9-161 c. Each 145-foot -long roll of reflective sheeting contains no splices.
2.Sheeting Application . Fabricate and apply legends in accordance with the Michigan Standard Highway Signs Manual or as shown on the plans.
3.Direct Applied Reflective Legend . Cut legends with a smooth, regular outline, free of ragged or torn edges, and with interior corners cut to 3/16-inch ± 1/16-inch radius. Apply legends in accordance with the reflective sheeting manufacturer ’s recommendations. For Type I aluminum extruded sign sections, cut the legend components along each metal sign section joint after applying the legend.
4.Non-Reflective Legend, Borders, and Arrows . Provide non-reflective black material for legend, borders, and arrows and apply using ink, silkscreen method, or non-reflective sheeting. Provide material and apply non-reflective legends, borders , and arrows in accordance with the manufacturer ’s specifications.
5.Reflective Panels. Cut reflective sheeting strips at least 2 inches wide. Provide sheeting on reflective panel for permanent sign supports matching the material type and background color of the sheeting off the sign mounted on the post, except for YIELD and DO NOT ENTER signs where the reflective panel will be red. Attach the reflective strip to PVC or 0.080- inch-thick aluminum substrate. If aluminum is used on a u-channel post , a backing plate is required. Attach the reflective panel with stainless steel fasteners.
C.Sign Hardware . Steel shapes, bars, and plates must meet the requirements of ASTM A36 /A36M or Department -approved equal and be hot-dip galvanized in accordance with AS TM A123 /A123M . Bolts, nuts, washers, U -bolts, and straps must be stainless steel alloy meeting the requirements of ASTM A320/A320M for Class 1, Grade B8. Provide self -locking, nylon insert -type nuts meeting the requirements of ASTM A320 /A320M and ASTM A194 /A194M for Grade 8F . If using U -bolts formed from straight bar stock, ensure that the U -bolts are formed by cold working. Aluminum alloy shapes and plates must meet ASTM B308/B308M for aluminum alloy 6061-T6. MDOT Standard Specifications for Construction Section 919 9-162 Cast post clips must conform to ASTM B108 /B108, for aluminum alloy 356.0-T6. Table 919- 3: Retroreflective Sign Sheeting Material Guidelines Sign Category Type Material Type Color Yellow warning W-series (non -school related), E13 -1, E13- 2, E11-1, OM -1, OM -2, OM -3 ASTM Type XI Fluorescent y ellow School S1-1, S4- 3, S4- 5, S4- 5a, school portion of S5 -1, W16-7p, W16- 9p, W16- 2, W16-2a ASTM Type XI Fluorescent y ellow or green Freeway guide White legends , borders , and arrows ASTM Type XI White Backg round including M8 series signs ASTM Type IV Green, brown, or blue Non-freeway guide All ASTM Type IV White on green, brown, or blue Regulatory Stop, yield, parking, black - on-white signs ASTM Type IV — Route markers — ASTM Type XI —
919.03 Delineators
Fabricate reflectors for delineators from Type III aluminum substrate and reflective sheeting material for rigid post applications or solely from reflective sheeting material for flexible post applications as shown on the MDOT Standard Plan R-127 series . Provide the Engineer with a copy of the manufacturer ’s certification that reflectors and posts meet the requirements of this subsection.
A.Aluminum Reflectors . Reflectors for mounting on rigid post must consist of Type XI retroreflective sign sheeting applied to Type III aluminum substrate. Fabricate the specified delineator reflector size(s) from the Type III aluminum substrate and round all exterior corners to a ¾ -inch radius . Remove any burrs that form while rounding the corners . Apply the sign sheeting to cover the entire face of the alum inum substrate and ensure that the sheeting is free of seams, wrinkles, bubbles, tears, gaps , and other defects after the corners are rounded and before the mounting holes are cut. The mounting holes must be 3/8 inch in diameter and located per the MDOT S tandard Plan R-127 series . Two mounting holes must be cut in each delineator reflector . Remove burrs from the mounting holes. MDOT Standard Specifications for Construction Section 919 9-163 B. Reflective Sheeting Reflectors. Provide reflective sheeting for mounting on flexible posts meet ing the material, color, and resistance to weathering requirements of ASTM D4956 for Type XI flexible retroreflective sheeting. Apply reflective sheeting in accordance with the manufacturer ’s specifications.
C.Mounting Hardware . Mounting hardware for aluminum reflectors must consist of a drive rivet or bolt system . Drive rivets may be aluminum or stainless steel . For aluminum drive rivets, b oth the pin and the collar must meet the requirements of ASTM B308/B308M for aluminum alloy 6061. Bolts must be stainless steel and accompanied by a locknut to produce a vandal -resistant attachment . A nylon washer is also required to be placed between the bolt head and the face of the reflector to protect the sign sheeting. Ensure that either sy stem has a large enough diameter that it will not be subject to pulling through the holes in the delineator reflectors or posts. Alternative fastening systems may be approved by the Engineer provided they form a vandal -resistant attachment.
D.Posts . Provide rigid steel or flexible delineator posts . Steel delineator posts must have a nominal weight of 1.12 pounds per foot and meet the requirements of subsection 919.04 for steel posts . Select flexible delineator posts from the Qualified Products List.
919.04 Steel Pos t Sign Supports and Square Tubular Steel Sign Supports
Provide steel post sign supports and square tubular steel sign supports, including sign posts, anchor sleeves, and anchor posts, meet ing the requirements of ASTM A702 .
A.Steel Post Sign Supports . Posts must be straight with a smooth, uniform finish and free of cracks, flaws, injurious seams, laps, blisters, ragged and imperfect edges, or other defects that affect the strength, durability, or appearance of the posts . Provide c ross-section, bolt-hole diameter , and spacing meet ing the requirements shown on the MDOT Traffic and Safety Sign Support Standard Plans . Align t he centers of the holes to coincide with the centerline of the posts . The punched bolt holes must provide a smooth, even sign post face. Holes and cutoff ends must be free of burrs. After fabr ication and hole punching, hot -dip galvanize steel posts in accordance with subsection 907.03.D. MDOT Standard Specifications for Construction Section 919 9-164 Provide p unched and coated posts weighing at least 95% of the nominal weight shown on the plans.
B.Square Tubular Steel Sign Supports . Provide square tubular steel sign supports meet ing the chemical, mechanical, and geometric properties of material used in the crash tests referenced in AASHTO ’s Standard Specifications for Structural Supports for Highway Signs, Luminai res, and Traffic Signals . Sign posts, anchor sl eeves, anchor posts, and connection hardware must be of the size and type shown on the MDOT Sign Support Standard Plans . Provide straight sign post s, anchor sleeves, and anchor post s with a smooth uniform finish and free from cracks and flaws or other defects that affect their strength or durability . Provide cut square ends free from burrs. Accurately space b olt holes of the specified diameter on all four sides of the sign post, anchor sleeve, and anchor post . Line up holes exactly opposite each other on opposing sides of the post in order to accommodate a bolt placed through two opposite sides . Align t he center of the holes with the centerline of the sign post, anchor sleeve, and anchor post. Punch t he bolt holes so the face of the sign post, anchor sleeve, and anchor post will have a smooth even surface. Hot-dip galvanize t he sign post, anchor sleeve, and anchor post after fabrication and hole punching in accordance with ASTM A123/A123M for Grade 65.
919.05 Sawed Wood Posts fo r Highway Signs
Provide sawed wood posts for highway signs meet ing the requirements of section 912 and Sign Support Standard SIGN -210.
919.06 Steel Column Breakaway Sign Supports
Provide structural steel for column sign supports and bolts, nuts, and washers for the structural steel joints meet ing the requirements of Sign Support Standard SIGN -220. Provide steel s hims meeting the requirements of ASTM A36/A36M and galvanize in accordance with ASTM A123/A123M.
919.07 Cantilever Sign Supports
A.Upright Column . Provide pipe for the upright column of Type E cantilevers meet ing the requirements of ASTM A53 /A53M for Grade B, MDOT Standard Specifications for Construction Section 919 9-165 Type E or Type S , steel pipe or meeting the requirements of API-5L for Grade X42 to X52. Provide p ipe for the upright column of Type J cantilevers meet ing the requirements of ASTM A 53/A53M for Grade B, Type E or Type S , steel pipe or meet ing the requirements of API -5L Grade X42.
B.Horizontal Arms . Provide pipe for the horizontal arms of Type E cantilevers meet ing the requirements of ASTM A53/A53M for Grade B, Type E or Type S , steel pipe or meeting the requirements of API -5L for Grade X42 to X52. Provide p ipe for the horizontal arms of Type J cantilevers meet ing the requirements of ASTM A500/A500M , Grade B or ASTM A519 /A519M, Grade 4140 annealed.
C.Gussets, Flanges, and Base Plates. Provide plate material for gussets, flanges, and base plates meet ing the requirements of ASTM A36/A36M . Plates must be free of sharp edges and irregularities.
D.Angles . Provide angles meeting the requirements of ASTM A709/A709M, Grade 36, or ASTM A36/A36M.
E.Pole and End Caps . Provide pole and end caps meet ing the requirements of ASTM A3 6/A36M .
F.Arm Connection Bolts . Provide high-strength bolts, nuts, washers , and lock washers for arm connections meeting the requirements of subsection 906.07.
G.Anchor Bolts . Provide anchor bolts, nuts, and washers meeting the requirements of subsection 908.14.
H.Dimension Tolerances. Ensure that cross sections, flatness, length, straightness, thickness, and camber of material before and after fabrication meet the tolerance requirements of ASTM A6 /A6M and AWS D1.1/D1.1M .
I.Galvanizing . Galvanize cantilever sign supports galvanized in accordance with ASTM A123 /A123M . Blast clean all components to remove excess mill scale and welding slag before galvanizing. Provide safeguards meeting the req uirements of ASTM A384/A384M and ASTM A385 /A385M to obtain high- quality galvanized coatings and to minimize distortion and warpage during galvanizing. Interconnect sections of fabricated pipe work or tube assemblies with open tee or miter joints and provid e each enclosed section with a vent hole at each end to provide drainage for the molten zinc and to prevent a hazard to personnel engaged in the galvanizing process. MDOT Standard Specifications for Construction Section 919 9-166 919.08. Truss Sign Supports Before applying dead loads, trusses must be cambered so the ordinate is within the allowable tolerances at the center of the assembled truss for the span length and type shown on the plans . Ensure that bearing surfaces fully contact each other in the relaxed position before tightening the flange bolts . The fabricator will determine the method of cambering the structure, with the Engineer ’s approval, to ensure that the method does not induce stress into the truss.
A.Upright Column . Provide hollow structural tubing for upright columns of Type C and D trusses meeting the requirements of ASTM A500/A500M for Grade B or API-5L for Grade X42 to X52. Provide pipe for upright columns of Type E trusses meet ing the requirements of ASTM A53/ A53M for Grade B , Type E or Type S , steel pipe or the requirements of API-5L Grade X42.
B.Horizontal Truss Boxes. Provide pipe for the horizontal truss boxes of Type C and D trusses meet ing the requirements of ASTM A53/A53M for Grade B, Type E or Type S , steel pipe or meeting the requirements of API-5L for Grade X42 to X52. Provide p ipe for the horizontal arms of Type E trusses meet ing the requirements of ASTM A500/A500M , Grade B, or ASTM A519 /A519M, Grade 4140 annealed.
C.Gussets, Flanges, and Base Plates. Provide plate material for gussets, flanges, and base plates meet ing the requirements of ASTM A36/A36M . Plates must be free of sharp edges and irregularities.
D.Angles . Provide angles meeting the requirements of ASTM A709/A709M, Grade 36, or ASTM A36 /A36M.
E.Pole and End Caps . Provide p ole and end caps meet ing the requirements of ASTM A3 6/A36M .
F.Truss Box Connection Bolts . Provide high-strength bolts, nuts, washers , and lock washers for truss box connections meeting the requirements of subsection 906.07.
G.Anchor Bolts . Provide anchor bolts, nuts, and washers meeting the requirements of subsection 908.14.
H.U-Bolts . Provide U -bolts and washers meet ing the requirements of ASTM A320/A320M , Grade B8, Class 1, stainless steel . Provide self-locking nylon insert -type nuts meeting the requirements of ASTM A320/A320M for Grade B8F.
I.Dimension Tolerances. Ensure that cross se ctions, flatness, length, straightness, thickness, and camber of material, before and after MDOT Standard Specifications for Construction Section 919 9-167 fabrication, meet the tolerance requirements of ASTM A6/A6M and AWS D1.1/D1.1M .
J.Galvanizing . Provide galvanized t russ sign supports in accordance with ASTM A123 /A123M . Blast clean all components to remove excess mill scale and welding slag before galvanizing. Provide safeguards meeting the requirements of ASTM A384/A384M and ASTM A385 /A385M to obtain high- quality galvanized coatings and to minimize distortion and warpage during galvanizing. Interconnect sections of fabricated pipe work or tube assemblies with open tee or miter joints and provide each enclosed section with a vent hole at each end to provide drainage for the molten zinc and to prevent a hazard to personnel engaged in the galvanizing process.
919.09 Overhead Lane Assignment Structures
Provide o verhead lane assignment structures meet ing the requirements of Sign Support Standard SIGN -760 and traffic signal typical plans.
919.10 Casings for Cantilever Drilled Piles
Provide casings for cantilever drilled piles meet ing the requirements of ASTM A252/A252M for Grade 2 steel . Casings must be smooth, watertight, and capable of withstanding handling stresses and external subsurface pressures . Provide c asing with an OD at least equal to the required shaft size.
Source: Michigan Standard Specifications for Construction, 2020 Edition. Pages 968–977 of 1,146.