Technical Report Documentation Page 

1. Report No. 

FHWA NHI 05-036

2. Government Accession No. 3. Recipient’s Catalog No. 

4. Report Date 

March 2005 

4. Title and Subtitle 

Guidelines for the Installation, Inspection, Maintenance and Repair 

of Structural Supports for Highway Signs, Luminaires, and Traffic 

Signals 

6. Performing Organization Code: 

7. Author(s) 

Michael J. Garlich, S.E., P.E. and Eric T. Thorkildsen, P.E. 

8. Performing Organization Report No. 

9. Performing Organization on Name and Address 10. Work Unit No. (TRAIS) 

Collins Engineers, Inc. 

123 North Wacker Drive, Suite 300 

Chicago, Illinois 60606 

11. Contract or Grant No. 

DTFH61-03-T-63040 

12. Sponsoring Agency Name and Address 13. Type of Report and Period Covered 

Office of Bridge Technology 

Federal Highway Administration 

400 Seventh Street, SW 

Washington, D.C. 20590 

14. Sponsoring Agency Code 

15. Supplementary Notes 

Contracting Officer’s Technical Representative (COTR): Larry Jones 

FHWA Technical Consultant: Thomas Everett 

16. Abstract: 

This document provides guidance for the installation, inspection, maintenance, and repair of 

structural supports for highway signs, luminaires and traffic signals. The primary purpose is to 

provide owners with information that can assist them in managing their inventory, identifying 

potential problem areas, and ensuring safe and satisfactory performance of these types of ancillary 

highway structures. The primary reason for compiling this guidance is increasing problems with 

wind induced vibration, fatigue, and even structural collapse of these support systems. 

Documented problems with these structures include questionable design and details, poor 

fabrication practices, and poor installation techniques. 

17. Key Words 

Sign Structures, Luminaires, Signal Structures, 

High Mast Lights, Mast Arms, Anchor Bolts, 

Inspection 

18. Distribution Statement 

No restrictions. This document is available from 

the National Technical Information Services, 

Springfield, Virginia 22161 

19. Security Classif. (of this report) 

Unclassified 

20. Security Classification (of this page) 

Unclassified 

21. No of Pages 

146 

22. Price 

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized 

TABLE OF CONTENTS 

Page

LIST OF FIGURES .................................................................................................................vi 

LIST OF TABLES..................................................................................................................viii 

1.0 INTRODUCTION........................................................................................................ 1 

2.0 SCOPE....................................................................................................................... 1 

3.0 MATERIALS............................................................................................................... 2 

 3.1 Material Types................................................................................................. 2 

 

 3.2 Corrosion Protection........................................................................................ 3 

 3.3 Notch Toughness ............................................................................................ 6 

4.0 LOAD EFFECTS ........................................................................................................ 7 

 4.1 General............................................................................................................ 7 

 4.2 Natural Wind Gusts ........................................................................................ 8 

 4.3 Truck-Induced Wind Gusts............................................................................. 9 

 4.4 Vortex Shedding........................................................................................... 10 

 4.5 Galloping ...................................................................................................... 11 

 4.6 Fatigue ......................................................................................................... 13 

5.0 ERECTION OF SIGN, SIGNAL, AND LIGHT SUPPORT STRUCTURES............... 14 

 5.1 General......................................................................................................... 14 

 5.2 Shop Inspection............................................................................................ 15 

 5.3 Preparation for Erection ............................................................................... 15 

 5.4 Erection Procedure....................................................................................... 17 

6.0 BOLTED CONNECTIONS ....................................................................................... 19 

 6.1 High-Strength Bolts ...................................................................................... 19 

 6.2 Stainless Steel Fasteners............................................................................. 20 

 6.3 Aluminum Fasteners .................................................................................... 21 

 6.4 Installation of Bolts and Fasteners ............................................................... 21 

 6.5 Anchor Rods................................................................................................. 24 

 6.5.1 General.......................................................................................... 24 

 6.5.2 Materials ........................................................................................ 24 

i 
TABLE OF CONTENTS (continued) 

Page 

 6.6 Base Plate and Holes................................................................................... 28 

 6.7 Anchor Rod Joints ........................................................................................ 29 

 6.8 Installation of Anchor Rods .......................................................................... 33 

 6.9 Procedures for Anchor Rod Tightening and Follow-Up Retightening........... 35 

7.0 MANAGEMENT OF INVENTORY............................................................................ 38 

 7.1 Collection of Inventory Information............................................................... 38 

 7.2 Database Development................................................................................ 38 

 7.3 Example Inventory Checklist ........................................................................ 39 

 7.4 Inventory Numbering .................................................................................... 40 

8.0 INSPECTION VARIABLES ...................................................................................... 40 

 8.1 Types of Inspections .................................................................................... 40 

 8.1.1 Initial Inspection............................................................................. 40 

 8.1.2 Routine .......................................................................................... 40 

 8.1.3 In-Depth......................................................................................... 40 

 8.1.4 Interim Inspection .......................................................................... 40 

 8.1.5 Damage Inspection........................................................................ 41 

9.0 INSPECTION FREQUENCY.................................................................................... 41 

10.0 INSPECTION PRIORITIES AND PLANNING.......................................................... 41 

11.0 REQUIRED RESOURCES ...................................................................................... 42 

 11.1 Suggested Personnel Requirements............................................................ 42 

 11.2 Tools and Equipment ................................................................................... 43 

 11.3 Traffic Control............................................................................................... 44 

 11.4 Safety ........................................................................................................... 46 

12.0 THE INSPECTION PROCEDURE ........................................................................... 47 

 12.1 Pre-Inspection Review of Available Materials (Desk Review)...................... 47 

 12.2 Inspection Nomenclature.............................................................................. 47 

 12.2.1 Sign Bridge .................................................................................... 47 

 12.2.2 Cantilever Sign Structure............................................................... 47

ii 
TABLE OF CONTENTS (continued) 

Page

 12.2.3 Mast Arm Structure........................................................................ 48 

 12.2.4 Signal Supports ............................................................................. 48 

 12.2.5 Light Poles..................................................................................... 48 

 12.2.6 Detailed Nomenclature .................................................................. 48 

 12.2.7 Orientation of Members ................................................................. 52 

 12.3 Sequence of Inspection................................................................................ 53 

 12.3.1 Sign Structures .............................................................................. 54 

 12.3.2 Mast Arm Structures and Signal Supports..................................... 56 

 12.3.3 Light Poles and High Mast Lights .................................................. 57 

 12.4 Non-Destructive Testing............................................................................... 60 

 12.5 Quality Control Plan ..................................................................................... 62 

13.0 ELEMENT INSPECTION ......................................................................................... 63 

 13.1 Element Definitions ....................................................................................... 63 

14.0 ELEMENT CONDITION RATING ............................................................................ 65 

 14.1 PONTIS Element Definitions and Ratings..................................................... 66 

15.0 INSPECTION REPORT ........................................................................................... 75 

16.0 MAINTENANCE AND REPAIR ................................................................................ 76 

 16.1 Prioritization of Work .................................................................................... 76 

 16.2 Routine Maintenance ................................................................................... 77 

 16.2.1 Foundations................................................................................... 77 

 16.2.2 Connections................................................................................... 78 

 16.2.3 Coatings......................................................................................... 78 

 16.3 Repairs ......................................................................................................... 79 

 16.3.1 Foundations................................................................................... 79 

 16.3.1.1 Concrete....................................................................... 79 

 16.3.1.2 Anchor Rods ................................................................ 80 

iii 
TABLE OF CONTENTS (continued) 

Page

 16.3.2 End Frames and Posts .................................................................. 80 

 16.3.2.1 Gouges......................................................................... 81 

 16.3.2.2 Impact Damage............................................................ 81 

 

 16.3.2.3 Corrosion....................................................................... 81 

 16.3.3 Trusses and Mast Arms................................................................. 81 

 16.3.3.1 Connections ................................................................. 81 

 16.3.3.2 Cracks.......................................................................... 81 

 16.3.4 Longitudinal Splits and Cracks ...................................................... 82 

 16.3.5 Composites for Repairs ................................................................. 83 

 16.3.5.1 Material Properties....................................................... 83 

 16.3.5.2 Repair Examples.......................................................... 83 

 16.3.6 Vibration Dampeners..................................................................... 84 

 16.3.6.1 Types of Dampeners.................................................... 84 

REFERENCES .................................................................................................................... 86 

APPENDIX A - EXAMPLE ELEMENT RATING 

 Foundation - S.01.......................................................................................................... A-1 

 Anchor Bolts - S.02 ....................................................................................................... A-2

 Base Plate (s) - S.03..................................................................................................... A-3

 Towers - S.04................................................................................................................ A-4 

 Tower to Truss/Chord/Arm Connection(s) - S.05.......................................................... A-5 

 Truss Chords/Arms - S.06............................................................................................. A-6 

 Truss Struts - S.07 ........................................................................................................ A-7 

 Cracks - S.08 ................................................................................................................ A-8 

 Chord Splice Connection(s) - S.09................................................................................ A-9 

 Sign Frame and L-Brackets - S.10.............................................................................. A-10 

 Sign Panels - S.11 ...................................................................................................... A-11 

 Catwalk - S.12............................................................................................................. A-12 

 Power and Luminaires - S.13...................................................................................... A-13 

 Sign Attachment(s) - S.15........................................................................................... A-14 

 Vertical Clearance, Camber and Alignment - S.16 ..................................................... A-15 

 Protection - A.17 ......................................................................................................... A-16 

 Other - S.18................................................................................................................. A-17 

iv 
TABLE OF CONTENTS (continued) 

Page

APPENDIX B - EXAMPLE INSPECTION REPORT FORMS ................................................ B-1 

APPENDIX C - SAMPLE INSPECTION REPORT ............................................................... C-1 

APPENDIX D - ULTRASONIC ANCHOR INSPECTION PROCEDURE .............................. D-1

v 
LIST OF FIGURES 

Number Page

Figure 1 Cantilever Sign Structure Failure................................................................... 1 

Figure 2 Failure of Weathering Steel Pole. Note the Corrosion Product ..................... 5 

Figure 3 Truck Passing Under VMS ............................................................................. 9 

Figure 4A Wind Effects .................................................................................................. 10 

Figure 4B Wind Effects .................................................................................................. 12 

Figure 5 Foundation Ready for Structure Installation ................................................. 17 

Figure 6 End Frame Being Set Onto Its Foundation.................................................... 18 

Figure 7 Assembled Truss Being Lifted Into Place..................................................... 19 

Figure 8 Star Pattern Tightening Sequence ............................................................... 22 

Figure 9 Bent Anchor Rod .......................................................................................... 26 

Figure 10 Headed Anchor Rod..................................................................................... 26 

Figure 11 Threaded-Shear-and-Uplift Joint .................................................................. 30 

Figure 12 Double-Nut-Moment Joint ............................................................................ 31 

Figure 13 Four Anchor Rod Group in a Template. Note Top is Galvanized................ 34 

Figure 14 Template Secured to the Forms to Ensure Proper Alignment. Note 

 Anchor Rod Threads Taped to Prevent Contamination by Concrete ........... 34 

Figure 15. A Hydraulic Torque Wrench Tightening Anchor Rod Nuts to 

 Achieve Needed Rotation............................................................................. 36 

Figure 16 Inspector Measures Sign Panel During Inventory/Inspection Operation...... 38 

Figure 17 Inspector Climbing Structure ........................................................................ 44 

Figure 18 Bucket Truck-Most Common Way to Access Sign Structure ....................... 44 

Figure 19 Inspector Uses Double Lanyard System ...................................................... 47 

Figure 20 Nomenclature Associated with Sign Bridge.................................................. 49 

vi 
LIST OF FIGURES (continued) 

Number Page

Figure 21 Nomenclature for Ancillary Structure Tower Supports ................................. 50 

Figure 22 Example-Truss to End Frame Connection Nomenclature............................ 51 

Figure 23 Sign Panel Support Components ................................................................. 52 

Figure 24 Orientation of Overhead Sign Structures-New York State 

 Department of Transportation ...................................................................... 53 

Figure 25 Hands on Inspection of Overhead Signs...................................................... 54 

Figure 26 Inspection of a Mast Arm Structure .............................................................. 56 

Figure 27 Post to Arm Connection Showing Poor Fit-Up Due to Use of 

 Incorrect Components .................................................................................. 57 

Figure 28 Loose Leveling Nuts on a High Mast Structure ............................................ 58 

Figure 29 High Mast Pole Slip Joint ............................................................................. 59 

Figure 30 Misaligned Luminaire Ring ........................................................................... 59 

Figure 31 Remotely Operated Inspection Device......................................................... 60 

Figure 32 Thickness Measurement at Critical Location of Structure Post.................... 61 

Figure 33 Ultrasonic Testing of Anchor Rods............................................................... 62 

Figure 34 Magnetic Particle Inspection of Weld at Post to Base Plate 

 Connection ................................................................................................... 62 

Figure 35 Base Plate with Added Anchor Rods ........................................................... 80 

Figure 36 Repair Detail for Overhead Sign Truss Chord Crack ................................... 82 

Figure 37 Repair of Truss Members Using FRP........................................................... 83 

Figure 38 Stockbridge Damper..................................................................................... 84 

Figure 39 Texas Flat Panel Damper............................................................................. 84 

Figure 40 Wyoming Strand Damper ............................................................................. 85

vii 
LIST OF TABLES 

Number Page

Table 1 Material Specifications ................................................................................... 2 

Table 2 Susceptibility of Types of Support Structures to Various 

 Wind-Loading Phenomena............................................................................. 7 

Table 3 Stainless Steel Bolts...................................................................................... 23 

Table 4 Installation Torque for Mild Steel Fasteners.................................................. 23 

Table 5 Tensile Properties for Anchor Rods.............................................................. 24 

Table 6 Acceptable ASTM A563 Nut, Grade, Finish and Style and ASTM F436 

 Washer Type and Finish for Threaded Anchor Rods ................................... 27 

Table 7 Nominal Anchor Rod Hole Dimensions ........................................................ 29 

Table 8 Nut Rotation for Turn-Of-Nut Pretensioning ................................................. 33 

Table 9 Element Definitions ...................................................................................... 63 

Table 10 Element Condition Rating............................................................................. 65 

Table 11 Repair Priority Rating ................................................................................... 76 

viii 
Guidelines for the Installation, Inspection, Maintenance 

 and Repair of Structural Supports for Highway Signs, 

Luminaires, and Traffic Signals 

1.0 INTRODUCTION 

This document provides guidance for the installation, inspection, maintenance, and repair of 

structural supports for highway signs, luminaires and traffic signals. The primary purpose is to 

provide owners with information that can assist them in managing their inventory, identifying 

potential problem areas, and ensuring safe and satisfactory performance of these types of 

ancillary highway structures. The primary reason for compiling this guidance is increasing 

problems with wind induced vibration, fatigue, and even structural collapse of these support 

systems, as seen in Figure 1. Documented problems with these structures include questionable 

design and details, poor fabrication practices, and poor installation techniques. 

Figure 1. Cantilever Sign Structure Failure. 

2.0 SCOPE 

This document is applicable to traffic signal structures, overhead highway signs, highmast 

luminaires and other large light poles, and also supports used for traffic monitoring equipment of 

various types, such as cameras. Support structures include cantilever, butterfly, and bridge 

support (also known as overhead or span type supports). These structures may be installed on 

foundations in the ground and/or pedestals built into highway side or median barriers or built 

into parapets or other parts of a bridge. Wood poles and signs, concrete poles, and span wires 

are not directly addressed, though some of the information contained herein may assist in 

evaluating those structures. 

1 
These Guidelines cover structures fabricated from galvanized or painted structural steel shapes 

and tubes, aluminum shapes and tubes, and weathering steel. These Guidelines focus on 

structural aspects of the supports as opposed to sign panels, signal heads, luminaires, or their 

mechanical and electrical connections. In many cases, due to their location adjacent to or 

extending over vehicular traffic, a support failure on these structures poses a significant threat to 

the traveling public. 

Design requirements for these structures are contained in the 4th edition of the “AASHTO 

Standard Specifications for Structural Supports for Highway Signs, Luminaires and Traffic 

Signals” (2001 Specifications) and are not directly discussed herein. In addition, several 

NCHRP Reports and industry specifications, which contain relevant information are listed in the 

references. 

3.0 MATERIALS 

3.1 Material Types 

Most support structures are fabricated from structural steel tubes, angles, and plate or from 

aluminum tubes, angles and plate. Common material specifications are shown in Table 1. 

Materials for bolts and anchor rods are discussed in Chapter 6. 

Table 1 

Materials Specifications 

Structural Steel ASTM A36, A572 or A709 

(or AASHTO equivalent) 

Structural Steel (Weathering) ASTM A572 W or A588 

Steel Tubing ASTM A500 

Steel Pipe ASTM A53, Grade B; A595 A, A135, 

API 52 

Aluminum 

Alloy and Temper 

5083 - H111/H321 

5456 - H111/H116/H321 

6061 - T6/T651 

6063 - T5/T6 

ASTM B209, B210, B211, B221, 

B241, B247, B308, B429 

Round steel tubes may be either cold formed tubing conforming to ASTM A500 or steel pipe 

conforming to ASTM A53 for resistance welded pipe, or one of several other ASTM or API 

(American Petroleum Institute) Specifications. Multi-sided tubes are manufactured by 

successive bending of a plate and welding the longitudinal seam. 

Aluminum members are available in a variety of alloys and tempers as is seen in Table 1. 

Alloys 6061-T6 and 6063-T5 are the most commonly used. In order to increase strength, 

aluminum is alloyed with other elements and, for the T series, heat treated. When these 

tempers are used in welded construction, their allowable stresses are reduced as the heat from 

welding reduces the beneficial heat treatment. Aluminum is both lightweight and corrosion 

resistant, which are beneficial when used for ancillary structures. However, the fatigue strength 

2 
of aluminum is only about 40 percent that of steels with comparable yield strengths, and the 

modulus of elasticity is one third that of steel, which increases member deflections. 

Shop fabrication of aluminum structures generally uses welded construction. Welding 

electrodes are selected to match the base metal, and welding is performed in accordance with 

ASW D1.2, “Structural Welding Code Aluminum.” 

Round Tubes are commonly used in the fabrication of both steel and aluminum structures since 

they provide: 

♦ Good bending resistance about any axis 

♦ Efficient sections for compression loads 

♦ Good torsional resistance 

♦ Lower drag coefficient and associated wind loading 

3.2 Corrosion Protection 

To protect steel structures from corroding some type of protective system is required. Though 

some ancillary steel structures may be painted, protection is most often provided by use of 

galvanizing or fabrication using weathering steel. Galvanizing is performed using the hot dip 

process. 

In the galvanizing process a zinc coating is metallurgically bonded to the steel surface. The zinc 

layer provides both a barrier coating for the steel and galvanic protection since the zinc 

preferentially is consumed before the steel corrodes. The coating process involves three basic 

steps: 

1. Surface Preparation 

It is essential that the material surface be clean and uncontaminated if a uniform, 

adherent coating is to result. Surface preparation is usually performed in sequence by 

caustic (alkaline) cleaning, water rinsing, acid pickling and water rinsing. 

 

The caustic cleaner is used to clean the material of organic contaminants such as dirt, 

paint markings, grease, and oil, which are not readily removed by acid pickling. Scale 

and rust are normally removed by pickling in hot sulfuric acid (150°F) or hydrochloric 

acid at room temperature. Water rinsing usually follows caustic cleaning and acid 

pickling. 

Surface preparation can also be accomplished using abrasive cleaning as an alternative 

to or in conjunction with chemical cleaning. Abrasive cleaning is a mechanical process 

by which sand, metallic shot, or grit is propelled against the material by air blasts or 

rapidly rotating wheels. Abrasive cleaning is often required to remove weld flux from 

weld areas. 

2. Fluxing 

The final cleaning of the steel is performed by a flux. The method of applying the flux to 

the steel depends upon whether the “wet” or “dry” galvanizing process is used. Dry 

3 
galvanizing requires that the steel be dipped in an aqueous zinc ammonium chloride 

solution and then thoroughly dried. This “preflux” prevents oxides from forming on the 

material surface prior to galvanizing. Wet galvanizing uses a molten flux layer that is 

floated on top of the bath metal. The final cleaning occurs as the material passes 

through this flux layer before entering the galvanizing bath. 

3. Galvanizing 

The material to be coated is immersed in a bath of molten zinc maintained at a 

temperature of about 850°F. The time of immersion in the galvanizing bath varies, 

depending upon the dimensions and chemistry of the materials being coated. Materials 

with thick sections will take a longer time to galvanize than those with thin sections. 

Materials with a high silicon content will produce thicker coatings for equal immersions in 

the molten zinc than those with a low silicon content. 

In addition to the effects of steel chemistry, the surface appearance and coating 

thickness are controlled by the galvanizing conditions. These include: a) variations in 

immersion time and/or bath temperature; b) rate of withdrawal from the galvanizing bath; 

c) removal of excess zinc by wiping, shaking or centrifuging; and d) control of the cooling 

rate by water quenching and/or air cooling. 

Effective galvanizing requires proper detailing and fabrication practices. Detailing and 

fabrication must allow both flux and galvanizing zinc to reach all areas of the assembly 

and to properly drain. The heat of the galvanizing process can cause distortion and 

induce cracking if not properly addressed. Galvanizing is performed in kettles into which 

the item to be galvanized must fit. For larger structures, it may be necessary to fabricate 

them in sections, spliced after galvanizing. In other cases, structures too long for the 

kettle may be “double dipped”; one half (or more) of the structure is immersed at an 

angle and galvanized, and the process repeated to galvanize the remaining area. 

Unless this is done vary carefully, some of the overlap area may be poorly galvanized. 

Double dipping also creates thermal stresses in a fabricated assembly that may lead to 

cracking if not properly controlled. 

The protective life of a galvanized coating is determined primarily by the thickness of the coating 

and the severity of exposure. Environments such as exposure to industrial air pollutants or 

marine environments cause more rapid deterioration of the galvanized coating than, say, clean, 

dry rural environments. 

Hot dip galvanizing of structures is normally specified to conform with ASTM A123 (AASHTO 

M111-80). This provides for a minimum coating thickness of 3.9 mils on material 0.25 inches 

and thicker. Based on data from the Hot Dip Galvanizer’s Association, service life of 30 to 40 

years may be expected in relatively benign environments while only 20 to 30 years may be 

expected in moderately aggressive atmospheres from a 3.9 mil coating. Many ancillary highway 

structures have been in service long enough that the galvanizing has deteriorated. In these 

cases, painting may be considered to extend the structure life. 

Weathering steel conforming to ASTM A588, also sometimes called by a trade name Cor-ten 

steel, uses nickel and chrome as alloying agents to produce a steel that can develop a 

protective oxide layer on the surface to minimize atmospheric corrosion. The extent of 

formation of the oxide layer depends on the levels of pollutants in the atmosphere as well as on 

4 
the length of time the material remains wet. Cycles of wetting followed by complete drying are 

needed to fully develop the protective surface. Welding electrode types should be specified to 

be compatible with the weathering steel and high strength weathering steel bolts are also 

available. 

Weathering steel, while used successfully in many projects, has also experienced deterioration 

in unfavorable environments or due to details that did not allow proper drying. FHWA Technical 

Advisory T 5140.32, “Uncoated Weathering Steel in Structures”, cautions against its use in the 

following environments: 

♦ Those exposed to highly corrosive air pollution 

♦ Those subject to salt spray or coastal marine salt-laden air 

♦ Those with very high rainfall and humidity or where there is constant wetness 

Areas of particular concern for corrosion of weathering steel ancillary structures are the internal 

corrosion of tubular members, and corrosion in the mating surface of slip joint connections. 

Tubular members will corrode on the inside if water or an electrolyte is able to continuously 

contact the surface. Members should contain drain holes and be detailed so that locations are 

not created where moisture can pool, or debris collect. Figure 2 shows the base of a 

weathering steel light pole that collapsed due to corrosion at its base. Slip joints draw water into 

the joint through capillary action. As this area does not dry well, pack rust develops which can 

generate sufficient force to split the tube vertically, starting at the bottom of the joint. Painting 

the slip joint surface before assembly, or sealing the bottom edge of the joint are two methods of 

improving the performance of this area. 

Weathering steel bases may also experience premature corrosion when they are buried in soil 

or covered by vegetation. 

Figure 2. Failure of Weathering Steel Pole. Note the Corrosion Product. 

5 
3.3 Notch Toughness 

Since fatigue cracking is possible in support structures, it is important that the materials used for 

anchor rods and main structural members have some minimum level of resistance to fatigue, 

defined by notch toughness (specified with the Charpy-V-notch test, or CVN) in order to avoid 

brittle fracture from small cracks. Materials that meet minimum CVN requirements are usually 

also more weldable and less susceptible to weld defects. 

Structural members and anchor rods should have CVN at least comparable to the non-fracturecritical bridge requirements; that is, the members and anchor rods should have at least 20 

Joules (15 ft-lb) at room temperature and, weld filler should be used which provides CVN of at 

least 27 Joules (20 ft-lb) at -18°C (0°F). Most present materials used for these support 

structures are believed to have toughness even greater than these levels of CVN would provide, 

even though it is not usually specified. Even though most of the grades of steel, filler metal, and 

anchor rods have adequate notch toughness, there is typically an inverse relationship between 

notch toughness and strength such that the higher strength materials usually have lower notch 

toughness. This is another good reason to use only lower-strength grades. 

The 2001 AASHTO Specifications require that steel "members" thicker than 13 mm (1/2 inch) 

meet the bridge steel CVN requirements. This is interpreted to not include anchor rods. It may 

be expensive or not even possible to get some anchor rods or tubular products with a 

supplemental CVN requirement. For example, some tubular members will be too thin to get 

even a sub-size CVN specimen. Since most materials meet the CVN requirement without 

having to actually specify it or pay for it, supplemental CVN specifications are not recommended 

for steel members or anchor rods other than for members thicker than 13 mm. Some exceptions 

may be when: 

♦ There is the possibility of seismic loading; 

♦ There are concerns about weldability of the steel members or anchor rods; or 

♦ A53 Grade B pipe is used, which is not really intended for structural use. 

Usually, anchor rods should conform to ASTM F1554-97, Standard Specification for Anchor 

Bolts, Steel, 36, 55, and 105-ksi Yield Strength, which is essentially the same as AASHTO 

M314-90, and these anchor rods have good fracture toughness. Alternatively, reinforcing bars 

conforming to ASTM A706-96, Standard Specification for Low-Alloy Steel Deformed and Plain 

Bars for Concrete Reinforcement may be threaded and used. Ordinary reinforcing bars 

conforming to ASTM A615-96, Standard Specification for Deformed and Plain Billet-Steel Bars 

for Concrete Reinforcement should not be used for these support structures because of 

possible low toughness. 

Using materials with additional notch toughness (above these minimum levels) would not 

significantly increase the time to failure of the structure by fatigue. This is because cracks grow 

at an exponential rate, and 95 percent of the life is consumed while the crack size is less than a 

few millimeters. Even though additional fracture toughness may correspond with a greater crack 

length at the time of failure, it does not correspond with a significantly longer time to failure. 

This is also the reason why, unless there is a suspected crack or there have been cracks in 

similar details in similar structures, it is usually not cost-effective to perform ultrasonic testing or 

other non-destructive testing (other than visual) on anchor rods or other details to locate fatigue 

6 
cracks. There is only a small window of time when the cracks are both large enough to detect 

and small enough to not yet cause fracture. In some states; however, ultrasonic testing is 

routine on four bolt bases of cantilever structures and partial testing is carried out on up to eight 

bolt bases. 

4.0 LOAD EFFECTS 

4.1 General 

Design loads for ancillary structures include dead and live loads, ice loads, and wind loads. For 

most structures, design will be governed by wind loads. 

Dead load includes the weight of the structural support itself, as well as the weights of signs, 

luminaires, traffic signals, lowering devices and any other appurtenances permanently attached 

to, and supported by, the structure. Temporary loads that may occur during maintenance 

should also be considered as dead load. AASHTO also requires that a live load be applied to 

any walkways and service platforms or ladders. 

An ice load, equivalent to a layer of ice 0.60 inches thick, is applied to all surfaces for structures 

located in regions considered susceptible to ice buildup. This area is shown in Figure 3-1 of the 

AASHTO Specifications, but generally includes all of the continental United States with the 

exception of a band running from the California coast and extending across the lower half of the 

southernmost states, plus all of Florida. 

The primary loads applied to sign, signal, and luminaire structures are due to natural winds. 

The structure must not only have sufficient strength to withstand the maximum expected wind 

loads, normally a once in 50 year maximum, but also the fatigue effects of fluctuating winds of 

lower force. There are four wind-loading phenomena that can lead to vibration and fatigue: 

natural wind gusts, truck-induced gusts, vortex shedding, and galloping. Each type of structure 

(e.g., signal, sign, or luminaires) is susceptible to either two or three of the four wind loads, as is 

shown in Table 2. The interaction of the support structure with the wind is dependent on the 

structure’s stiffness and shape. For instance, galloping which can occur in cantilever signal 

structures, does not occur in bridge support configurations. 

Table 2 

Susceptibility of Types of Support Structures to 

Various Wind-Loading Phenomena 

Type of Structure Galloping Vortex 

Shedding 

Natural 

Wind 

Truck 

Gusts 

Cantilevered Sign (one- or two-chord) X X X 

Cantilevered Sign (four-chord) X X 

Bridge Support (Sign or Signal) * X X 

Cantilevered Signal X X X 

Luminaires X X 

Note: X indicates structure is susceptible to this type of loading 

* Vortex shedding has occurred in monotube bridge supports and can occur in cantilevered 

structures if the sign or signal is not attached, such as could occur during installation. 

7 
The high flexibility and low damping of cantilevered support structures makes them susceptible 

to resonant vibration in the wind. The flexible cantilevered structures have low natural 

frequencies of about 1 Hz (period of vibration of 1 second), which is in the range of typical wind 

gust frequencies. The closeness of the wind gust frequencies to the natural frequency causes 

resonance or dynamic amplification of the response. In addition, typical damping ratios in these 

structures are extremely low (less than one percent of critical damping). The low damping 

increases the amplification of the wind-induced vibrations. 

Usually, the greater the length of the cantilevered mast arm, the more susceptible the support 

structure will be to wind-induced vibration. In recent years, the span length of the cantilevered 

mast arms has increased significantly. One example is a 22-m (72-ft) long cantilevered signal 

support structure near the University of Tampa, which vibrates frequently due to its extreme 

flexibility. 

Personnel involved in installation, inspection, maintenance, and repair of ancillary support 

structures should understand the wind loading and response of various support structures. This 

will enable them to recognize these problems in the field and have a better understanding of the 

important reasons for quality control during the structure erection phase. 

4.2 Natural Wind Gusts 

The most common type of wind-induced vibration in support structures is from ordinary wind 

gusts or fluctuations of the wind velocity. In the 2001 Specifications, these gusts are referred to 

as natural wind gusts to distinguish them from truck-induced wind gusts. Natural wind gusts 

exert a fluctuating force that is primarily horizontal, and the resulting motion of the mast arm is 

also primarily horizontal, although there is often a significant vertical motion as well. In the 2001 

Specifications, the natural wind gust pressure is applied horizontally to the projected frontal area 

of all surfaces, including the structural members, as well as the sign and signal attachments. 

In cases where fatigue cracking was caused by natural wind gusts, cracking developed over a 

period of at least several years. In light poles, the connection of the arm supporting the lights to 

the pole top has cracked. In cantilevered sign and signal support structures, the cracks will 

usually manifest at the connection of the mast arm to the pole, with cracks forming along the 

sides of the connection. Natural wind gust loading has also caused cracks at truss connections 

and at the base of the pole, at the weld joining the pole to the base plate, at the top of the 

stiffeners, at hand holes, or at the anchor rods. 

As shown in Table 2, all structure types are potentially susceptible to natural wind gusts, which 

act on all members of the structure as well as the attachments. The most flexible and most 

lightly damped structures are more susceptible, however. 

Support structures in certain areas of the country that are very windy are particularly susceptible 

to vibration and fatigue from natural wind gusts. Typically, these are places where the mean 

annual wind velocity is greater than 5 m/s (10 mph). 

8 

These places where there are frequent constant winds, and support structures are at risk for 

fatigue cracking due to natural wind gust loading, are not the same places with the maximum 

peak wind velocities that are identified on wind maps, such as those in ASCE 7-98. These maps 

show the maximum wind speed that occurs over a 50-year period that is used for strength 

design. It is noteworthy that there are very few fatigue failures of cantilevered sign and signal 
supports after hurricanes or other large storms. These once-in-a-lifetime wind gusts have little 

influence on fatigue. 

The fatigue-limit-state natural wind gust loads in the 2001 Specifications are derived for winds 

that are exceeded about 2 hours each year. Such areas, surprisingly, are not necessarily those 

with occasional very high winds such as hurricanes or tornadoes. For example, the four places 

in the United States with the greatest wind velocities that are exceeded at least 2 hours per year 

are: 

♦ Tatoosh Island, Washington: 28 m/s (62 mph) 

♦ Clayton, New Mexico: 24 m/s (53 mph) 

♦ Point Judith, Rhode Island: 24 m/s (53 mph) 

♦ Cheyenne, Wyoming: 24 m/s (53 mph) 

4.3 Truck-Induced Wind Gusts 

The passage of trucks beneath support structures induces both horizontal and vertical gust 

loads on the structure, creating a motion that is primarily vertical but may also include a 

significant horizontal component as well. The magnitude of the horizontal truck gust is negligible 

relative to the natural wind gust and is therefore ignored in the specifications. The vertical truck 

gust load in the specifications is an equivalent static pressure range applied to the underside of 

the mast arm or truss and any attachments. Due to the large depth of variable-message signs 

(VMS) in the direction of traffic flow (up to 1.2 m for older signs), the support structures are the 

most susceptible to truck-induced wind gust fatigue because they present a large area in the 

horizontal plane, as seen in Figure 3. 

Figure 3. Truck Passing Under VMS. 

Fatigue cracking from truck-induced wind gusts usually develops over a period of several years. 

However, one case of a failure of a cantilever VMS structure, reported by DeSantis and Haig, 

was to a structure less than 1 year old. The cracks will usually manifest at the connection of the 

9 
mast arm to the pole, at truss connections; and at the base of the pole to the weld joining the 

pole to the base plate, at the top of the stiffeners, at hand holes, or at the anchor rods. 

The truck-gust pressure is proportional to the speed of the trucks, so signs located on major 

highways are more susceptible than those where the trucks are traveling slowly. Also, there is a 

vertical gradient for the truck-induced gust pressure, so the greater the clearance between the 

tops of trucks and the bottoms of the signs, the less the susceptibility to truck-induced vibration. 

The truck-gust loads essentially go to zero at a height of 10 m (32.8 ft) above the roadway. 

4.4 Vortex Shedding 

Vortex shedding is the shedding of vortices on alternate sides of a symmetric member (i.e., one 

without any attachments). Vortex shedding can result in resonant oscillations of a pole in a 

plane normal to the direction of wind flow as shown in Figure 4(A). In the 2001 Specifications, 

the vortex shedding pressure range for fatigue design is applied horizontally to the projected 

area of one side of the pole to calculate the fatigue stress ranges in the details. 

Elevation

Movement 

Plan

Movement 

Wind Direction 

A. Vortex Shedding 

Figure 4A. Wind Effects 

As shown in Table 2, only luminaires support structures (i.e., light poles) have exhibited 

problems from vortex shedding. However, other simple cantilever poles, such as camera poles 

may also be susceptible. Luminaire support structures may occasionally exhibit excessive 

10 
vibration from natural wind gusts. However, if there is a vibration problem with luminaire 

supports, it is typically due to vortex shedding. 

In some cases, severe vibration from vortex shedding has persisted long enough to cause 

fatigue cracking. This may not require a long time. For example, in the case of some aluminum 

light poles that failed after a windstorm in New Jersey, it was found that the fatigue cracks 

initiated and propagated to failure in just one night. In light poles, cracks are usually observed at 

the base of the pole or at the weld joining the pole to the base plate or transformer base. If there 

are stiffeners or gussets reinforcing the pole to base plate connection, then the cracks will 

typically form at the tops of the stiffeners. In some cast aluminum pole bases, the cracks will 

occur at various details in the castings. If there are hand holes, cracks may appear around the 

perimeter of these. Cracked anchor rods have also occurred. 

Vortex shedding tends to occur with steady continuous winds at a critical velocity. The velocity 

need not be very high, but it has been found that significant vibration does not occur unless the 

velocity is greater than 5 m/s (10 mph). The periodic frequency of the vortex shedding can lock 

in on the natural frequency of the pole, resulting in very large alternating forces acting 

transverse to the wind flow direction. There are videotapes of luminaire supports vibrating so 

severely that the amplitude of the vibration was on the order of the pole diameter. Vortex 

shedding may result in frequent burnouts of the light filaments. Occasionally, the vibration is so 

severe that fatigue cracks will appear. 

Although vortex shedding can "lock in" and continue as the velocity increases or decreases 

slightly, if the velocity changes by more than 20 percent, the vortex shedding will stop. Gusty 

variable winds, such as might occur in a severe storm typically will not cause vortex shedding. 

In fact, if the wind velocity is greater than 15 m/s (35 mph), the wind is generally too turbulent for 

vortex shedding to occur. In summary, the winds that are dangerous for vortex shedding are 

steady winds in the velocity range 5 to 15 m/s (10 to 35 mph). 

Recent studies have verified that vortex shedding can occur in tapered as well as prismatic 

circular poles with almost any diameter. (Note: this is contrary to some statements in the 2001 

Specifications) In a few cases, sign and signal support structures have exhibited vortex 

shedding on the mast arms before the attachments (signs or signal heads) were mounted. After 

mounting, this is no longer a problem. Consequently, it is recommended that mast arms never 

be erected before these attachments are mounted. NCHRP Report 469 reports that vortex 

shedding of long monotube bridge support structures has also occurred. 

4.5 Galloping 

Galloping is different than vortex shedding but also results in large-amplitude, resonant 

oscillations perpendicular to the direction of wind flow as shown in Figure 4(B). Unlike vortex 

shedding, galloping occurs on asymmetric members (i.e., those with signs, signals, or other 

attachments) rather than circular members. Therefore, it is the mast arms rather than the poles 

that are susceptible to galloping. Galloping has caused mast arms to move up and down with a 

range greater than 1 m. According to NCHRP Report 469, a large portion of the vibration and 

fatigue problems that have been investigated for cantilevered sign and signal support structures 

were caused by galloping. 

11 
Plan

Elevation

Wind 

Movement

B. Galloping

Figure 4B. Wind Effects 

Galloping is caused by the attachments (i.e., signs/signals). The number of signs and signal 

heads, their configuration, area, connection detail, and the direction of wind flow significantly 

influence the susceptibility for galloping. Signal attachments configured with backplates and 

subjected to flow from the rear are most susceptible to galloping. However, all types of signal 

heads and signs have been observed to be affected by galloping, even those with louvered 

backplates. 

Galloping also requires uniform steady winds rather than gusty winds. However, in contrast to 

vortex shedding, galloping can continue over a large range in wind velocity. The mode of 

vibration for galloping is swaying of the mast arm in the vertical direction. This mode typically 

has a frequency closer to 1 Hz (1 second period). Higher modes of vibration have not been 

observed. Galloping requires twisting of the mast arm as well as vertical motion. Consequently, 

flexible monotube cantilever support structures are particularly susceptible to galloping. As 

noted above, monotube bridge support structures may be susceptible to vortex shedding; 

therefore, one can assume that these structures may also be susceptible to galloping from the 

sign or signal attachments. However, typical bridge support structures where the sign bridge 

consists of three-dimensional, three-chord or four-chord trusses are not susceptible to vortex 

shedding or galloping. 

12 
In the 2001 Specifications, the galloping pressure is applied vertically (like a shear stress) to the 

projected frontal area of all sign and signal attachments. The galloping loads are quite severe, 

so when they are applicable, they will typically govern the fatigue design. Therefore, mitigation 

devices will have significant cost benefits in reducing the effects of galloping as opposed to 

natural wind gusts or truck-induced wind gusts. 

In most cases that have been investigated, the fatigue cracking that has occurred from galloping 

has developed over a long period of a year or more where there may have been many days of 

winds that caused galloping. In cantilevered sign and signal support structures, the cracks will 

usually manifest at the connection of the mast arm to the pole or at the base of the pole. In truss 

mast arms, the cracks may form at the truss connections, usually those closest to the pole. If 

there is a flanged splice detail in the mast arm close to the pole, this may also be a critical 

location where cracks may form. At the base of the pole, cracks may form at the weld joining the 

pole to the base plate. If there are stiffeners or gussets reinforcing the pole to base plate 

connection, then the cracks will typically form at the tops of the stiffeners. If there are hand 

holes, cracks may appear around the perimeter of these. Cracked anchor rods have also 

occurred. 

Cantilevered sign support structures with mast arms fabricated in three- or four-chord trusses 

have also never been reported to vibrate from vortex shedding or galloping. Apparently, these 

three-dimensional truss mast arms are sufficiently stiff to resist galloping. However, there are 

many reported instances of cantilevered two-chord trusses with signs and signals galloping. 

Typically, the longer the cantilever mast arm, the more susceptible to galloping. 

4.6 Fatigue 

Fatigue resistance of particular details is determined by testing full-scale structural members 

under cyclic loads. The loading is characterized in terms of the nominal stress in the structural 

member remote from the welds or bolts in the detail. The nominal stress is conveniently 

obtained from standard design equations using member forces and moments. Testing has 

indicated that the primary effect of constant amplitude loading can be accounted for in the liveload stress range (i.e., the difference between the maximum and the minimum stress in a 

loading cycle). Thus, it is the fluctuation of the stress and not the absolute value of the stress 

that affects fatigue. The constant dead load stress does not affect fatigue. 

The strength and type of steel have a negligible effect on the fatigue resistance expected for a 

particular detail. The welding process and minor deviations in weld quality from AWS D1.1 

standards, while important, also do not typically have a significant effect on the fatigue 

resistance. The independence of the fatigue resistance from the type of steel and weld filler 

metal greatly simplifies the development of design rules for fatigue since it eliminates the need 

to generate data for every type of steel. As previously pointed out, the fatigue resistance of 

aluminum is significantly less than that of steel. 

Fatigue failure of a support structure basically occurs because the stress ranges resulting from 

the wind or truck-induced gusts exceed the fatigue thresholds at critical details. Usually, these 

failures cannot be blamed on weld defects; rather, they are an indication that the structure is not 

adequately designed for the fluctuating loads and is experiencing excessively large stress 

ranges. This is a good reason to believe that other similar structures will soon be having similar 

cracking problems. Therefore, if a fatigue failure has occurred in a structure, one cannot be 

13 
complacent about inspecting similar structures. All similar structures should be intensively 

inspected immediately. 

It is a commonly held, but incorrect assumption that cracks may be caused by overloading the 

structure. In some cases, large variable message signs have been placed on a truss designed 

for flat green signs, and then fatigue problems have occurred. These problems are likely due to 

the increased area of the sign, which increases the gust load ranges and the associated stress 

ranges from wind and trucks, rather than from the increased dead load stress. 

In the 2001 Specifications, the fatigue design provisions for support structures are given in 

Section 11. These fatigue design provisions are similar to those in the bridge specifications. The 

fatigue design procedures are based on control of the nominal stress range and knowledge of 

the fatigue threshold of the details. Various details are shown in Figure 11-1 of the 2001 

Specifications. Each of these details is assigned a "Stress Category" in Table 11-2, and the 

fatigue threshold stress range for each category is given in Table 11-3 of this Specification. 

Support structures should be designed so that the stress ranges due to the fatigue design loads 

are less than the fatigue thresholds for each detail, thus ensuring that fatigue will not occur even 

for a large number (hundreds of millions) of applied load cycles. Design calculations should be 

prepared and stamped by a professional engineer explicitly showing the fatigue design as well 

as the traditional allowable stress design for strength. 

Since the fatigue resistance of various grades of steel and anchor rods is the same, it typically is 

not cost-effective to use high-strength steel, higher than 420 Mpa (60 ksi) yield strength. If the 

dimensions of the members or anchor rods are decreased to take advantage of the highstrength steel for the maximum strength design loads, the stress ranges under the fatigue 

design loads will increase and fatigue will become more of a problem. 

5.0 ERECTION OF SIGN, SIGNAL, AND LIGHT SUPPORT STRUCTURES 

5.1 General 

This section recommends procedures for the erection of support structures. Construction of the 

concrete foundations is not covered. However, guidance on grouting of base plates and the 

proper installation of anchor rods is presented. 

For this discussion, Quality Control (QC) refers to all means and methods utilized by a 

contractor and/or a subcontractor to assure ancillary structures are properly fabricated, erected 

and constructed. Quality Assurance (QA) refers to all means and methods utilized by a public 

owner or an agent acting on their behalf to assure adequate QC is employed by the contractor 

and that satisfactory quality in the work is achieved. 

Numerous defects found during condition assessment inspections have been attributable to 

poor fabrication or erection practices. Proper erection is the responsibility of the erection 

contractor. The erection contractor should perform inspection and testing to verify that 

installation is in accordance with the project specifications. Records should be kept of the dates 

and results of any inspection, and these records should be available for the Engineer of Record 

or their representative to review. The Engineer of Record may require that their representative 

witness the installation and inspection. Inspection by the owner, or its representative, during 

erection is strongly recommended. 

14 
5.2 Shop Inspection 

Shop inspection of ancillary structures is encouraged, particularly for welded cantilever sign and 

overhead bridge structures. The inspections should assure that the structures conform to the 

design drawings and that details such as drain holes, boltholes, connection details and welds 

are properly executed. Overall member configuration, alignment, and coating condition should 

also be checked. In many instances, detailed design of ancillary structures is provided by the 

vendor, within overall guidance of general configuration plans prepared by the owner. Thus a 

wide variety of details and fabrication methods are normally encountered in the finished 

structures. Vendor detail drawings and calculations should be reviewed for conformance with 

the 2001 Specifications and to identify poor details prior to starting fabrication. 

The 2001 Specification requires weld inspection, which should be performed and documented 

by the fabricator. Section 5.15 of the Specifications provides requirements for steel structures, 

while Section 6.9 applies to aluminum structures. Weld quality for steel structures should 

conform to AWS D1.1, Structural Welding Code - Steel, and for aluminum structures to AWS 

D1.2, Structural Welding Code - Aluminum. For tubular aluminum structures, workmanship 

requirements for Class I structures are the minimum, while Class II should be considered for 

critical structures. 

Due to the types of joint configurations and welds found in ancillary structures, weld inspection 

requirements contained in current fabrication specifications are not sufficient to ensure defect 

free welds during shop fabrication. This is one reason that close field inspection of ancillary 

structures to find detectable cracks is particularly important. NCHRP Report 469, “FatigueResistant Design of Cantilevered Signal, Sign, and Light Supports,” contains a discussion of the 

Specification requirements for welding inspection and their effectiveness. 

5.3 Preparation for Erection 

The erection contractor should be responsible for assembling design and fabrication documents 

and having them available for review by the owner or their representative. The design and 

fabrication documents should include a set of design drawings; shop drawings; the name and 

contact information for the designer/consultant of record; design calculations (stamped by a 

professional engineer explicitly showing the fatigue design as well as the traditional allowable 

stress design for strength); the name and contact information (including location of plant) of 

fabricator of record; welding procedure specifications; inspection reports; and copies of material 

mill certificates for the anchor rods, structural bolts, and the main members (not including 

stiffeners, base plates, flange plates, and other small plates). As an option, the owner may elect 

to have some of this information, not directly needed for erection, submitted directly to him/her. 

The erection contractor, considering the weight and stability of the pieces to be erected, should 

carefully plan the erection procedure for each job. Light poles, including light supports with 

relatively short cantilevered arms, may be fully assembled on the ground and erected in one 

piece. Cantilevered sign and signal supports should be erected in two pieces. It has been found 

that it is nearly impossible to properly tighten the double-nut anchor rod connection when a 

completely assembled cantilevered support structure is suspended from the crane. Bridge type 

structures should have the end frames erected, followed by the bridge. 

15 
Prior to erection, the separate parts of the structure, posts, end frames, mast arms, and trusses, 

should be inspected for bent or damaged members, damaged coatings, distortion, and defective 

fabrication that would affect proper erection. Structures can be damaged during shipment as 

well as by improper unloading and storage at the site. Localized defects in the galvanizing 

coating should be repaired in accordance with the requirements of ASTM A780, “Standard 

Practice for Repair of Damaged and Uncoated Areas of Hot-Dip Galvanized Coatings.” 

In addition to establishing that the structure was properly fabricated, the contractor should 

visually inspect the structure for cracks. Cracks may occur during fabrication or galvanizing of 

the structures. In addition, fatigue cracks may occur in structures from the loads they 

experienced in transport, as has happened with several aluminum trusses with tube to tube 

welded connections. Fatigue cracks will generally occur between bolt holes or along the toe of 

the welds parallel to the weld axis. Longitudinal seam welds, any hand holes or other 

attachments, or any splices or joints should be inspected closely. All defects in the structure 

should be reported to the owner or their representative so that proper repairs may be 

authorized. 

If it is not clear whether the visual indication is a crack or possibly just a crack in the coating or a 

scratch, the indication should be further investigated using magnetic particle (MT) testing or 

dye-penetrant (PT) testing. These testing procedures are explained in detail in AWS D1.1. It is 

generally not worthwhile to inspect areas using one of these methods unless there is a good 

reason to suspect there is a crack. Ultrasonic testing may be useful in some circumstances, but 

generally the cracks will have penetrated through the thickness of the member, and the MT and 

PT methods can find them more economically. Enclosed tubes, especially the diagonals and 

verticals in trusses, can rupture from the galvanizing (if adequate vent holes are not used or 

become clogged). If these tubes fill with water, they should be drained by drilling a 13-mm (0.5-

inch) diameter hole near the bottom of the tube, but at least 25 mm (1 inch) from the welded 

connection. If the water remains undrained, it can accelerate corrosion or rupture the tube if it 

freezes. 

It should be verified prior to beginning erection that there will be no fit-up problems when the 

parts of the structure are assembled in the field. The slope of the surfaces of parts in contact 

with bolt heads or nuts, and the faying surfaces, should be equal to or less than 1:20 with 

respect to a plane that is normal to the bolt axis. However, even if the surfaces are within 

tolerances, 100-percent mating between the two flanges will usually not be achieved. The 

structure should be rejected, however, if more than 25 percent of the surface area is visibly not 

in firm contact after snugging the bolts. This contact surface is discussed further in Section 6.4. 

The erector should verify that the foundations are set to the proper elevation and anchor rods 

are set in the correct pattern and orientation, are of the correct size, and are plumb with the 

specified extension and thread length above the top of concrete, as seen in Figure 5. 

16 
Figure 5. Foundation Ready for Structure Installation. 

The anchor rods generally should not be subjected to erection or service loads until the 

concrete reaches its 28-day specified strength. In some cases, with the approval of the owner 

or owner’s Engineer, the post may be attached to the anchor rods after as few as 7 days. 

If necessary, camber should be built into the support structure. The base plate should always be 

designed to be level. The support structure base plate should never be sloped on the anchor 

rods to achieve a camber, because the misalignment of the base plate will make it nearly 

impossible to properly tighten the anchor rods. 

An ancillary structure inventory database should be established and the inventory number 

should be clearly placed on the support structure. The inventory number is most often stenciled 

on with paint, though numbers may also be stamped into the post or even magnetic bar codes 

can be attached. The design, materials, and fabrication documents discussed previously should 

be filed in a way that they are accessible and linked to the database. The date of erection 

should be recorded and the inspection results and any repairs or corrective measures taken 

should be explained in detail in the database. 

5.4 Erection Procedure 

Prior to starting actual erection, all traffic control and other safety measures as required by the 

project specifications must be in place and reviewed for compliance. Erection generally 

requires at least some lane closures, and may involve short-term total road closures. In areas 

of high traffic, erection may have to be performed at night, requiring temporary lighting for both a 

safe and complete installation. 

The actual erection process begins by placing and leveling the leveling nuts. Typically, the 

bottom of the leveling nuts are set approximately 6 mm (0.25 inches) above the top of the 

concrete. The posts or end frames are then erected on the anchor rods (Figure 6), being 

careful not to damage the threads on the anchor rods. The base plate should be leveled by 

bringing up the leveling nuts on the low sides. To minimize shear and bending in the anchor 

rods, the bottom of the leveling nuts must not be more than one anchor rod diameter above the 

17 
top of the concrete. Finally, the anchor rod nuts should be tightened. Recommendations for 

tightening are presented later, in Section 6.5. 

Figure 6. End Frame Being Set Onto Its Foundation. 

After the anchor rod nuts are properly tightened, the post or end frame is released from the 

crane. For light poles, the erection is now complete, except for the post-erection retightening of 

the anchor rods, as discussed in Section 6.9. 

For cantilevered signal and sign support structures, the erection continues with the mast arm or 

truss. The cantilevered mast arm or truss is balanced on the crane and is brought up to position 

and bolted to the post. 

For sign bridges, the sections (if there are more than one) are normally connected to one 

another on the ground and set in one lift. Lifting points must be located so that the bridge is not 

overstressed during lifting, (Figure 7). With the bridge set on the end supports, alignment 

should be verified and connections brought up to final tightness. With the cantilever arm, or 

bridge in position, a check of overhead roadway clearance should be performed and 

documented. 

Signs, signals, and other attachments are normally attached to the cantilever arm or sign bridge 

on the ground before erection. Even very large heavy variable message sign boxes should be 

attached to their supporting members on the ground, and this can be done off site. If the 

attachments are not attached to a cantilever structure when it is erected, they should be 

attached immediately after erection. This is because the bare mast arms with no attachments 

are vulnerable to vortex shedding, which can quickly become destructive. 

18 
Figure 7. Assembled Truss Being Lifted Into Place. 

6.0 BOLTED CONNECTIONS 

Sign, signal, and lighting structures utilize a variety of bolted fasteners in their construction. 

These range from large anchor rods and high strength bolted structural connections to 

“secondary” fasteners for signs, wind beams, saddles, and the like. Fasteners also include Ubolts, bolted clips, and similar items. While procedures for installing high strength bolts are 

established in AASHTO, and recommended procedures for anchor rod nut installation are 

provided herein, installation practices for other types of bolted fasteners varies. 

Ancillary structures are subject to vibration due to fluctuating wind loads. Unless properly 

tensioned, this can cause fasteners to become lose and contribute to their failure. Though the 

implication of failure of an anchor rod or bolt in a structural connection may seem apparent, 

even secondary fasteners that fail can lead to sign breakage and small items falling into traffic. 

Connections should be designed with due consideration of the fatigue stresses induced by 

variations in wind loads. 

6.1 High-Strength Bolts 

The design, specification, handling, installation, and inspection of bolted joints in steel support 

structures should be in accordance with the Specification for Structural Joints Using ASTM 

A325 or A490 Bolts dated June, 2000 by the Research Council on Structural Connections 

(RCSC). Only a few points especially important for support structures are mentioned in these 

Guidelines. The Federal Highway Administration Report No. FHWA-SA-91-031, “High-Strength 

Bolts for Bridges” provides an in depth treatment of bolt supply, installation, and testing (this 

manual is available for download at fhwa.dot.gov/bridge). The U-bolts and other details for 

connecting luminaires, signs, and signal heads to the structure are not discussed. The 

manufacturers design these details, and there have been few problems with these details in the 

past. 

19 
Structural joints for galvanized steel sign, signal, and light support structures should only utilize 

galvanized ASTM A325 high strength bolts or galvanized ASTM F1852 twist-off-type, tension 

control bolt assemblies. The joints should be between steel members, and it is essential that 

the joints be properly pretensioned to resist vibration. These bolts have a very high strength so 

that they can supply high forces to compress the joint when they are tightened to their 

prescribed pretension. These joints actually carry load through compression-generated friction 

on the faying surfaces rather than through the bolt. The job of the bolt is to maintain the 

pretension and the associated precompression of the faying surfaces. 

When a pretensioned joint is subject to cyclic fatigue loads, it acts as if the pieces pressed 

together were actually monolithic (i.e., the bolts themselves feel only about 20 percent of the 

load range), with the majority of the load range transferred through the faying surfaces. When a 

bolted joint is not properly pretensioned, all the load range is transferred through the bolts and 

they may quickly fail by fatigue. 

Galvanized ASTM A325 bolts and related washers and nuts are available either hot-dip 

galvanized or mechanically galvanized. Hot-dip galvanizing is recommended as it provides a 

heavier coating with corresponding increased life. 

Heavy-hex nuts should meet the requirements of ASTM A563 (Grade DH; galvanized and 

lubricated) or ASTM A194 (Grade 2H; galvanized and lubricated). Heavy-hex nut dimensions 

should meet the requirements of ANSI/ASME B18.2.6. Flat galvanized circular washers should 

meet the requirements of ASTM F436. Washers should be used under the nut. If the bolt head 

is to be turned during the tightening procedure, then a washer should also be provided under 

the head. Lock washers should never be used with high strength bolts. For oversized holes, 

plate washers 8 mm (5/16 inch) should be used rather than flat washers. Plate washers should 

be structural grade steel and should be galvanized, if used with galvanized fasteners. 

Lock washers should not be used with high strength bolts. Their variability of deformation under 

load does not provide for proper bolt installation tension. 

Compressible-washer-type, direct-tension indicators should meet the requirements of ASTM 

F959. When the direct-tension-indicator (DTI) is used under the nut, an ASTM F436 washer 

should be placed between the bolt and the direct-tension indicator. When the direct-tensionindicator is used under the bolt head, an ASTM F436 washer is required under the DTI when 

the DTI is placed on an oversized hole and between the bolt head and the DTI when the bolt 

head is the turned element. 

The bolt length used in a connection should be such that the end of the bolt is flush with or 

projecting beyond the face of the nut when properly installed. 

6.2 Stainless Steel Fasteners 

Connections for stainless steel structures, which are rare, and aluminum structures utilize 

stainless steel bolts and related fasteners. Stainless steel offers excellent corrosion resistance. 

Stainless fasteners are most often supplied from American Iron and Steel Institute (AISI) Type 

304 or 316 stainless material. Type 304 is the most common. Nuts and washers should match 

the steel type of the bolt or fastener. Stainless fasteners should conform to the requirements of 

ASTM F593, “Standard Specification for Stainless Steel Bolts, Hex Cap Screws, and Studs” and 

20 
ASTM F594 “Standard Specification for Stainless Steel Nuts.” Stainless steel bolts are supplied 

either hot finished or cold finished. Cold finished Type 304 and 316 bolts have an ultimate 

tensile strength of 620 MPa (90 ksi), versus 516 MPa (75 ksi) for hot finished. However, cold 

finished bolts are only supplied if specifically specified and are not normally “off-the-shelf” items. 

Since installation tension for stainless fasteners is not as high, or as well controlled, as it is for 

high strength steel bolts, the use of lock washers is common with stainless fasteners. Lock 

washers are placed under the nut and help to reduce loosening due to structure vibration and 

load fluctuation. 

6.3 Aluminum Fasteners 

Aluminum fasteners are sometimes used for miscellaneous applications, such as sign 

connections. Aluminum bolts are not generally used in structural connections, even on 

aluminum sign structures, due to a tendency to stretch and hence loosen under cyclic tension 

loadings. 

Aluminum bolts should conform to ASTM B316 “Structural Specification for Aluminum-Alloy 

Rivet and Cold Heading Wire and Rods.” Bolts are available in several alloy-tempers, with 

2024-T4 and 6061-T6 the most common. Off-the-shelf bolts are typically alloy-temper 2024-T4, 

which has an allowable shear stress of 96 MPa (14 ksi) and an allowable tension stress of 158 

MPa (23 ksi) as given in the “Aluminum Design Manual” published by the Aluminum 

Association. 

6.4 Installation of Bolts and Fasteners 

All bolts and miscellaneous fasteners must be installed in accordance with established industry 

practice or manufacturer’s requirements. Though not desirable, some procurement practices 

may result in sign structures being erected by firms with little experience in proper installation of 

high strength bolts. In addition, unless a contractor is erecting a group of sign structures, only a 

few high strength bolts may be needed. Where the quantity of fasteners is small, it may not be 

realistic to expect the same bolt documentation and testing as would be provided on a steel 

bridge erection project. 

Fastener components should be protected from dirt and moisture in closed containers at the site 

of installation. Fastener components should not be cleaned of lubricant that is present in the as 

delivered condition. Components that accumulate rust or dirt resulting from plant or job-site 

conditions should not be incorporated into the work. Galvanized bolts that have been fully 

pretensioned shall not be reused. 

A common bolted connection in ancillary structures consists of bolted flange or face plates that 

match face-to-face. Such connections occur at truss chord splices, long mast arm splices, arm 

to pole connections, and similar locations. According to fabricators, it is almost impossible to 

achieve a perfectly flat faying surface on the flanged connection that mates at the exact angle 

with a perfectly flat faying surface on the opposing flange. The fabricator should select a weld 

type and procedure for the plate to tube (or member) connection that minimizes misalignment 

and distortion of the faying surfaces. As stated above, the slope of the surfaces of parts in 

contact with the bolt head or nut, and the faying surfaces, should be equal to or less than 1:20 

with respect to a plane that is normal to the bolt axis, but 100-percent mating between the two 

flanges will usually not be achieved. Compressible materials (such as gaskets, insulation, or 

21 
sheets of other metals) should not be placed between these flanges, even to try to achieve 

better contact. Tightening of bolts should be performed in a manner that brings the faying 

surfaces up “evenly.” For flange type connections, a star tightening pattern as shown in Figure 

8 is recommended. 

4 

5 8 

7 6

3

1 

2

Figure 8. Star Pattern Tightening Sequence. 

For high strength bolted joints, according to the RCSC, the surfaces need to be brought into firm 

contact, but it is acceptable to have isolated areas where there is no contact. The fact that gaps 

may exist in the faying surfaces does not prevent the bolt preload from being developed. The 

end plate thickness is enough to bridge the gaps and develop the desired bolt tension. The 

snug-tightened condition is defined by the RCSC as the tightness that is attained with a few 

impacts of an impact wrench or the full effort of an ironworker using an ordinary spud wrench to 

bring the plies into firm contact. The structure should be rejected if there is more than 25 

percent of the surface visibly not in contact after snugging the bolts. The Engineer of Record 

may approve the use of steel shims or repairs to the structure to correct this problem. 

For high strength bolted joints using ASTM A325 galvanized bolts, allowable methods of 

installation, to develop the required pretension, include the turn-of-nut method, calibrated 

wrench method, twist-off-type tension-control bolt method, or direct-tension-indicator method. 

These are described in Section 8 of the RCSC Specification. Procedures for each installation 

method are detailed in report FHWA-SA-91-031, High Strength Bolts for Bridges, Appendices 

A2 through A6. A detailed coverage of high strength bolting may also be found in the Steel 

Structures Technology Council (SSTC) Structural Bolting Handbook. 

Pre-installation verification testing should be performed using a Skidmore-Wilhelm device as 

indicated in Section 7 of the RCSC Specification. However, since ancillary structures may 

contain only a few high strength bolts, this testing is often not performed. High strength bolts 

should be inspected for proper bolt tightening as required by the RSCS Specification for the 

chosen method of bolt installation. The inspection verification data should be provided to the 

owner’s representative. Where connections are made up overhead with one piece suspended 

22 
from a crane, pretensioning and inspection should be performed prior to releasing the load thus 

minimizing induced stresses into the joint. 

Installation methods for fasteners other than high strength structural bolts are not standardized. 

As with high strength bolts, proper joint fit-up that does not induce bending into the bolts, 

selection of proper bolt length to allow full nut engagement, and use of washers must be 

adhered to. It is recommended that stainless and mild steel bolts be installed to minimum 

torque values. This at least assures a minimum bolt tension and consistency between multiple 

bolts in a connection. It should be noted that it could be beneficial to the owner to perform 

torque/tension testing on nonstructural bolts to establish the tension being provided for specified 

torques. This would allow for more complete joint evaluation. 

The Specialty Steel Industry of the United States (SSIUS) recommends that stainless bolts be 

tightened to an installation torque value that varies with bolt size as shown in Table 3. 

Table 3 

Stainless Steel Bolts 

Installation Torque 

Size Dia, mm 

(in) 

Type 304 KN-mm 

 (ft-lb) 

Type 316 KN-mm 

(ft-lb) 

12 (1/2”) 59 (43) 62 (45) 

16 (5/8”) 127 (93) 133 (97) 

20 (3/4”) 175 (128) 181 (132) 

24 (1”) 393 (287) 410 (300) 

Galvanized mild steel bolts and threaded fasteners such as U-bolts are also used in ancillary 

structures. These include treaded fasteners conforming to ASTM A307 as well as to the Society 

of Automotive Engineers (SAE) Grades 1 and 2. Typical ultimate tensile strengths are from 420 

MPa (60 ksi) to 440 MPa (64 ksi). These fasteners should be installed to the torque values 

shown in Table 4, and verified using a properly calibrated torque wrench. 

Table 4 

Installation Torque for Mild Steel Fasteners 

Bolt Size, Dia. mm 

(in) 

Minimum Torque KN-mm 

(ft-Lb) 

10 (3/8) 20 (15) 

12 (1/2) 50 (37) 

16 (5/8) 101 (74) 

20 (3/4) 164 (120) 

22 (7/8) 260 (190) 

23 
Aluminum fasteners are not recommended for structural connections. Miscellaneous or 

secondary fasteners of aluminum should be installed to torque valves supplied by the 

manufacturer. 

6.5 Anchor Rods

6.5.1 General 

Anchor rods provide attachment of the structure to its foundation. They can carry large forces, 

particularly for cantilever structures where overturning is resisted by a moment at the base 

which is carried through the anchor rod group. The design and proper installation of anchor 

rods has traditionally received little technical guidance as it fell wholly in neither the realm of 

steel structures nor concrete structures. 

The "Specification for Steel-to-Concrete Joints Using ASTM F1554 Grades 36, 55, and 05 

Smooth Anchor Rods, ASTM A615 and A706 Grade 60 Deformed Bars, and AWS D1.1 Type B 

Studs" is currently being developed by the Research Council on Structural Connections and 

may eventually be published by the RCSC. For the design strength of the concrete anchorage, 

this specification refers to current American Concrete Institute ACI 318 criteria. For use in 

highway ancillary structures, the ACI load factors and resistance factors may be modified by the 

State to be consistent with AASHTO design provisions. NCHRP Report 469 also provides 

guidance. 

6.5.2 Materials 

Anchor rods are supplied in conformance with ASTM F1554 “Standard Specification for Anchor 

Bolts, Steel, 36, 55 and 105 Ksi Yield Strength.” ASTM F1554 provides for three different 

grades of anchor rods: Grade 36 (painted blue on the projecting end), Grade 55 (painted yellow 

on the projecting end), and Grade 105 (painted red on the projecting end). The specified 

minimum yield strength (Fy) and specified minimum tensile strength (Fu) for each Grade are 

given in Table 5. 

Table 5 

 Tensile Properties for Anchor Rods 

Tensile Property 

ASTM 

F1554 

Rod 

Grade 36 

ASTM 

F1554 

Rod 

Grade 55 

ASTM 

F1554 

Rod 

Grade 105 

ASTM 

A706 

Bars 

Grade 60 

Minimum Yield 

Strength Fy, MPa (ksi) 248 (36) 380 (55) 720 (105) 415 (60) 

Minimum tensile 

Strength Fu, MPa (ksi) 400 (58) 516 (75) 860 (125) 550 (80) 

ASTM F1554 was passed in 1994, and is essentially the same as AASHTO M314-90, although 

there are some differences. ASTM F1554 Grade 36 is essentially the same as ASTM A36 or 

ASTM A307 Grade C, and ASTM F1554 Grade 105 is equivalent to ASTM A193 Grade B7. 

24 
ASTM 1554 supercedes these specifications, and the older specifications should no longer be 

referenced for anchor rods. The ASTM A325 or A490 specifications should not be specified for 

anchor rods. The A325 and A490 bolts are intended for use in structural connections. 

Since the fatigue strength of these various grades of anchor bolts is the same, it is usually not 

worthwhile to use the Grade 105 anchor rods. If an existing support structure (not designed for 

fatigue in accordance with the 2001 Specifications) has Grade 105 anchor rods that were 

designed for strength only, the size of the anchor rods may be much less than would be the 

case if Grade 55 or Grade 36 anchor rods were used. Consequently, the stress ranges in these 

Grade 105 anchor rods may be much greater, making them particularly likely to experience 

fatigue cracking. Grade 105 anchor rods should be especially evaluated to see if stress ranges 

calculated using the 2001 Specifications are large enough that fatigue would be expected to 

occur quickly. If so, an inspection of the rods using ultrasonic testing methods may be 

warranted. 

For similar reasons, the use of anchor rods conforming to ASTM A722 with minimum tensile 

strength of 150 ksi should be discouraged, but may occur in some existing structures. Where 

such rods have been used, an inspection using ultrasonics should be performed. 

Anchor rods are normally supplied in one of the following shapes: 

♦ Bent anchor rods. These rods are F1554 smooth anchor rods with the embedded 

end bent as to form a hook (Figure 9). The anchorage to the concrete is by means 

of the hook. The adherence between the shank and the concrete is not reliable and 

should not be counted in design. Grade 105 bent rods should be avoided because 

they have been shown by Jirsa, et. al. to straighten before they reach any other more 

predictable steel or concrete mode of failure. 

♦ Headed anchor rods. These rods are F1554 smooth anchor rods with a head in the 

embedded end (Figure 10). The anchorage to the concrete is obtained by the head. 

Typically, the "head" consists of one or more nuts, with either heavy washers or a 

plate washer. For lightly loaded anchorages, headed studs could also be utilized. 

♦ Deformed bars. Concrete reinforcing bars (ASTM A 706-96, Standard Specification 

for Low-Alloy Steel Deformed and Plain Bars for Concrete Reinforcement may be 

threaded and used for anchor rods. Ordinary reinforcing bars conforming to ASTM 

A615-96, Standard Specification for Deformed and Plain Billet Steel Bars for 

Concrete Reinforcement have been used in the past. However, because of possible 

low toughness, ordinary reinforcing bars should not be used for non-redundant, 

fatigue susceptible support structures such as cantilevers and high-mast luminaires. 

Reinforcing bars may rely on the deformations along the bar for anchorage to the 

concrete, may include an ACI standard hook, or may be threaded on the embedded 

end and utilize nuts and a washer for anchorage. The tensile properties of common 

Grade 60 reinforcing bars are also given in Table 5. The A706 specification should 

be used if the anchor rod is to be welded or used in seismic applications. 

25 
Figure 9. Bent Anchor Rod. 

t 

Lh 

L

 L = length of rod 

Lh = length of hook 

 t= length of threads

F

t2 

t 

L

 L = length of rod 

 H = height of nut or head 

 F = width across flats or 

 head diameter 

t1 = length of threads 

 (exposed end) 

t2= length of threads 

 (embedded end)

H 

Figure 10. Headed Anchor Rod. 

The use of Uniform National Coarse (UNC) threads is recommended, especially for galvanized 

anchor rods, although ASTM F1554 also permits the less common 8 UN series threads. The 

full range of diameters (1/4 to 4 inches) of anchor rods with UNC threads can theoretically 

sustain the overtapping of corresponding nuts (required to allow for zinc coating from 

26 
galvanizing) without stripping, while this may not be true for 8 UN threads. It should be noted 

however, that the Michigan Department of Transportation feels that the use of 8 UN threads is 

advantageous. They have not experienced any problems with thread stripping. 

The thread class (tolerances) of the anchor rods should also be specified, and typically Class 

2A is satisfactory. Class 2A will be provided by default if class is not specified. 

Nuts on the embedded or projected end of the anchor rod should conform to ASTM A563 nuts. 

The recommended nut style, grade and finish are shown in Table 6. This table is based on the 

appendix of the ASTM A563 specification. 

Table 6 

Acceptable ASTM A563 Nut, Grade, Finish and Style 

And ASTM F436 Washer Type and Finish for Threaded Anchor Rods 

Anchor Rod 

Anchor Rod 

Size mm (in.)* Finish 

ASTM A563 Nut Style, 

Grade and Finish 

ASTM F436 Washer 

Type and Finishb 

Plain 

(uncoated) 

Hex: A, B, D, DH; plain 

Heavy Hex: A, B, DC

, C3, DC, 

DHd

, DH3: plain 

1; plain 

6-38 

(1/4 - 1 1/2) 

Galvanized 

Hex: A, B, DC

, DHd; 

Galvanized and lubricated 

Heavy Hex: A, B, CC

, C3, DC, 

DHd

, DH3; galvanized and 

Lubricated 

1; galvanized 

Plain 

(uncoated) 

Heavy Hex: A, B, CC, C3, DC, 

DHd

, DH3; plain 1; plain 

F1554 

Grade 

36 

Over 38-100 

(1 1/2 – 4) Galvanized 

Heavy Hex: A, B, CC

, C3, DC, 

DHd

, DH3; galvanized and 

Lubricated 

1; galvanized 

Plain 

(uncoated) 

Hex: A, B, DC

, DHd; plain 

Heavy Hex: A, B, CC

, C3, DC, 

DHd

, DH3; plain 

1; plain 

6-38 

(1/4 - 1 1/2) 

Galvanized 

Heavy Hex: A, B, CC

, C3, DC, 

DHd

, DH3; galvanized and 

Lubricated 

1; galvanized 

Plain 

(uncoated) 

Heavy Hex: A, B, CC, C3, DC, 

DHd

, DH3; plain 1; plain 

F1554 

Grade 

55 

A706 

Grade 

60 Over 38-100 

(1 1/2 – 4) Galvanized 

Heavy Hex: A, B, CC

, C3, DC, 

DHd

, DH3; galvanized and 

Lubricated 

1; galvanized 

Plain 

(uncoated) 

Hex: DC

, DHd; plain 

Heavy Hex: CC

, C3, DC, 

DHd

, DH3; plain 

1; plain 6-38 

(1/4 - 1 1/2) 

Galvanized Heavy Hex: DHd

, DH3; galvanized 

and lubricated 1; galvanized 

Plain 

(uncoated) Heavy Hex: DHd

, DH3; plain 1; plain 

F1554 

Grade 

105 

Over 38-100 

 1 1/2 – 4 Galvanized Heavy Hex: DHd

, DH3; galvanized 

and lubricated 1; galvanized 

a

 Applicable only to F1554 Grade 55 anchor rods. 

b

 Applicable only if washer is required. 

c

 ASTM A194 nuts Grade 2 or 2H are acceptable equivalents for Grades C and D nuts. 

d

 ASTM A194 nuts Grade 2H are acceptable equivalents for Grades DH nuts. 

*Note: Metric bolt sizes and threads are different, for soft conversion 1 inch = 25 mm

27 
Corrosion protection is particularly important for fatigue critical anchor rods, since corrosion 

pitting can degrade the fatigue resistance. Anchor rods, nuts, and washers that are used 

outdoors are typically galvanized. ASTM F1554 permits hot dip galvanizing by ASTM A153 

Class C or mechanically deposited by ASTM B695, Class 50. The purchaser should specify 

which of these processes should be used or state "no preference." The hot dip process provides 

a heavier zinc coating and longer life. Galvanized deformed bars may be used and should be 

specified by referencing ASTM A767. Galvanized anchor rods should always be shipped with 

the nuts pre-assembled to the anchor rods to ensure good fit and ability to run the nut down the 

threads easily. This should be specified in the purchase order because it is not required in the 

ASTM specifications. 

There are two types of washers for anchor rods: standard washers and plate washers. Standard 

washers are ASTM F436 washers. When "Normal Holes" are used, plate washers at least 5/16

inch thick should be used. Plate washers should be structural grade steel and be galvanized to 

match the anchor rods. Beveled standard washers should be used when the outer face of the 

base plate has a slope that is greater than 1:20 with respect to a plane that is normal to the 

anchor axis. If an anchor bolt is incorrectly installed resulting in larger out-of-plumbness, 

specially fabricated washers may be needed to allow proper bearing of the connected parts. 

6.6 Base Plate and Holes 

Research described in NCHRP Report 412 has shown that the base plate should be at least as 

thick as the anchor rod diameter to provide for even distribution of the load and to minimize 

prying forces. The minimum distance from the center of the anchor rod hole to the edge of the 

base plate should be two times the nominal diameter of the anchor rod. 

Base plates are normally supplied shop welded to the posts or pole. The most common pole to 

base plate connection is a weld socket joint, where the central portion of the base plate is cut 

out so the pole can slip into the opening. As a result, particularly for large diameter poles such 

as high mast lights, the base plate is in reality a base ring with a resulting decrease in plate 

bending stiffness. Field inspectors have reported observing the base plates actually flex 

between anchor rods for high mast lights due to normal wind loads. This tendency can be 

reduced by use of a larger number of anchor rods or a thicker base plate. 

Holes may be thermally cut in the base plates. In most cases, the anchor rod holes in the base 

plate should be "Shear Holes" with the dimensions shown in Table 7, as recommended in 

NCHRP Report 469. Research by Cook has shown that this size of hole is adequate for a 

correct transfer of shear forces from the base plate to the anchor rods and to allow plastic 

redistribution of shear forces. On the other hand, if anchor rods are not required to transfer 

shear, only holes labeled as “Normal Holes” in Table 7 are needed. These normal holes are the 

same holes recommended in the AISC Manual of Steel Construction for base plates. They are 

oversized to allow for an easy placement of the base plate during erection. 

28 
Table 7 

Nominal Anchor Rod Hole Dimensions 

Nominal Anchor Rod Hole Dimensionsa, b Anchor Rod , in.* 

Diameter 

In.* 

Shear Holes 

(diameter) 

Normal Holes 

(diameter) 

1/2 

5/8 

3/4 

7/8 

1 

1 1/4 

1 1/2 

1 3/4 

≥2 

5/8 

13/16 

15/16 

1 1/16 

1 1/4 

1 9/16 

1 13/16 

2 1/16 

db + 5/16 

1 1/16 

1 3/16 

1 5/16 

1 9/16 

1 13/16 

2 1/16 

2 5/16 

2 3/4 

db + 1 1/4 a

 The upper tolerance on the tabulated nominal dimensions shall not exceed 1/16-in. 

b

 The slightly conical hole that naturally results from punching operations with properly 

matched punches and dies in acceptable. 

* Note: Metric bolt sizes and threads are different, for soft conversion 1 inch = 25 mm

6.7 Anchor Rod Joints 

There are several types of joints for the base plate to foundation connection. These have 

evolved within particular industries, with the so called threaded-shear-and-uplift joint and 

double-nut-moment joint used for nearly all ancillary structures. These are cost effective and 

provide good performance when properly designed and installed. 

The threaded-shear-and-uplift joint rests directly on the concrete or on a grout pad (Figure 11). 

The base plate is held down by nuts atop the base plate. Single nuts are most common, but 

double nuts are sometimes used. For proper joint performance, the base plate must be in direct 

contact with the grout and not be supported by leveling nuts or shim pacts. One technique to 

achieve full grout support is to set the base on shim pacts to proper elevation, grout the base 

and then remove the shims and grout the resulting voids. Only then can the anchor rods be 

fully pretensioned. Use of proprietary prepackaged grout mixes, so called “non-shrink grout” is 

recommended and should be carefully installed to manufacturers’ recommendations. The 

threaded-shear-and-uplift joints can develop some resistance to bending moment as a couple 

between compressive bearing force on the grout and tensile forces in the anchor rods. It may 

be difficult to retain the pretension in the anchor rods under cyclic loads as the base plate wears 

the grout. For these reasons, this type of joint is not recommended by NCHRP Report 469 for 

large cantilevered support structures, although it is still commonly used for many luminaires and 

small traffic signal supports. This type of joint is suitable for bridge support structures where 

there are multiple posts. 

29 
Grout Leveling Plate 

Nut 

Anchor Rod 

Base plate

Nut 

Pole/Post 

Figure 11. Threaded-Shear-and-Uplift Joint. 

All three shapes of anchor rods will perform correctly in this type of joint. The anchor rods 

transmit shear and tension, while compression forces are transmitted directly by bearing of the 

base plate on the concrete and are not carried by the anchor rods. As a result of the 

compression on the concrete, friction will be developed between the base plate and the 

concrete. Shear friction strength should be calculated using the factored load combination that 

gives minimum possible compression from dead load along with the maximum uplift that is 

consistent with the lateral load that is being evaluated. The effect of live load should not be 

included when calculating the shear friction strength unless the live load causes the lateral load 

or uplift. 

If the friction strength, is greater than the factored applied shear or torsion on the joint, anchor 

rods are not needed for transmitting shear or torsion. In fact, if the friction is sufficient to handle 

the shear, and if there is no uplift, then anchor rods are, in theory, not needed at all for service 

loads. In this case, anchor rods must be provided for stability during erection but need not be 

designed for the service loads. If the anchor rods are designed only for the factored loads during 

erection, NCHRP Report 469 recommends including a minimum lateral shear load equal to 5.0 

percent of the axial load from dead load during erection. The anchor rods must also resist a 

minimum moment to account for an ironworker on the pole as required by OSHA. 

If, on the other hand, the factored loads exceed the friction capacity of the joint, anchor rods 

should be assumed to transmit the entire shear because the friction may no longer be effective 

at the deformation levels required to develop the shear strength of the anchor rods. The shear 

30 
strength of the anchor rods may be taken as the smaller of the sum of the steel shear strengths 

of the contributing individual anchor rods or the concrete shear strength of the anchor group. 

Whenever anchor rods are needed for transmitting shear in this type of joint, the base plate 

should have shear holes. Also, in the same case, bearing of the anchor rod on the walls of the 

shear holes should be checked. As an option, normal holes can be provided in the base plate 

and plate washers having shear holes can be placed over the anchor rods and field welded to 

the base plate after the base is set. The plate washers and welds must be designed to transmit 

all calculated shear forces and welding must conform to applicable portions of the AWS Bridge 

Welding Code. 

In double-nut-moment joints, the base plate stands off from the concrete foundation and bears 

on leveling nuts (Figure 12). Thus, the base plate is attached to anchor rods through double 

nuts: the leveling nut and a top nut (or nuts). This type of joint may be suitable for any type of 

support structure and is required for cantilevered support structures designed by the 2001 

Specifications. Washers should be used under both nuts, and beveled washers should be used 

if the misalignment exceeds 1:40 for the double-nut-moment joints. Double-nut-moment joints 

are easy to level and plumb and are also very reliable for transmitting moment to the foundation; 

therefore, they are satisfactory for non-redundant structures and seismic or fatigue-loaded 

structures such as highway sign, signal, and light supports. 

Pole/Post 

Nut

Anchor Rod

Baseplate Nuts 

Figure 12. Double-Nut-Moment Joint. 

Double-nut joints are pretensioned between the nuts only, and the pretension has no effect on 

strength. Research reported in NCHRP Report 412 has shown that the pretension gives slightly 

better fatigue resistance, but the effect is not that significant. The anchor rod below the leveling 

nut is not pretensioned but will still see the full cycle of fatigue loads. More importantly, the 

31 
pretension ensures that there is a good load distribution among the various anchor rods. 

Therefore, there are special tightening procedures for these joints. 

Headed rods and deformed bars are best suited for double-nut-moment joints. In double-nutmoment joints, anchor rods are designed to resist all the axial forces, moments, and shears 

applied to the joint, even if there is grout under the base plate. 

Opinions on whether or not grout should be used with double-nut-moment joints differ. As noted 

above, in a properly designed joint, all loads are resisted in the anchor rods. Due to the greater 

stiffness of the anchor rods compared to the grout, and the tendency of the grout, even for socalled “non-shrink grouts”, to shrink, though perhaps imperceptibly, below the bottom of the 

base plate, little load transfer to the grout is likely even if assumed so in design. Grout, if well 

installed, may pick up loads due to very high or unexpected load cases. Proper grout 

installation is difficult when base plates tend to be rings, as with large light poles. A means must 

be provided to restrict grout flow inside the base ring while fully filling beneath it. For these 

reasons, and several listed below, grouting of double-nut-moment joints is generally not 

recommended: 

♦ It may crack, retain moisture, and then promote corrosion. 

♦ It makes it impossible to inspect and retighten bottom nuts if necessary. 

♦ In order to place the grout after the base plate is in place, the standoff distance 

between the top of concrete and the bottom of the leveling nut may exceed the 

recommended distance equal to the anchor rod diameter. 

Where base plates are not grouted, a stainless steel wire mesh should be placed around the 

base plate to eliminate debris from accumulating beneath the base plate and keep animals out 

and protect electrical wires if present. 

There is an unfortunate trend toward using fewer very large anchor rods. It is always better to 

use more, smaller anchor rods than fewer, bigger anchor rods. Especially if the failure mode is 

fatigue and the structure is non-redundant, it is essential to have at least eight anchor rods in 

the anchor rod group. In the event of one anchor rod failure from fatigue, the increase in the 

load on the neighboring anchor rods is tolerable for the case of an eight-bolt group, and there 

will be weeks or months typically before a second anchor rod fails and total collapse occurs. 

This gives the joint some measure of redundancy, even if the structure is non-redundant. The 

fatigue failure of one anchor rod from a six-or four-bolt group, however, may lead to immediate 

collapse. 

If the embedded head of an ASTM F1554 anchor rod is a nut or is fastened with nuts, the head 

nut or the nuts fastening the head should be prevented from rotating while the anchor rod is 

tightened. Two methods have been shown to prevent rotation: 

♦ Tack weld the nut to the anchor rod on the unstressed (bottom) side of the nut if the 

ASTM F1554 rod is a grade 36 rod or a grade 55 rod. 

♦ Jam another nut on the head nut for any grade of ASTM F1554 rod. 

Neither the tack weld nor the jam nut will affect the ultimate or fatigue strength of the rod. 

32 
6.8 Installation of Anchor Rods 

Proper installation of the anchor rods is the responsibility of the foundation contractor, and 

inspection and testing is to be performed by the foundation contractor. Records should be kept 

of the dates and results of testing and inspection, and these records should be available for the 

Engineer of Record or their representative to review. The Engineer of Record may require that 

their representative witness the inspection and testing. 

Prior to placing the anchor rods in the concrete, an anchor rod rotation capacity test should be 

run with at least one anchor rod from every lot. This test may be run in a Skidmore-Wilhelm 

device or in a mockup of the base plate using a small piece of plate with one hole of equivalent 

grade, thickness, and finish. The test consists of Steps 2 through 14 of the tightening procedure 

(presented later), adapted as necessary because there is no post or crane, and there is only 

one anchor rod. NCHRP Report 469 recommends that the nut be rotated at least to the 

required rotation given in Table 8. After the test, the nuts should be removed and inspected for 

damage to their threads. 

Then the anchor rod is removed from the test plate and restrained while the nuts are turned 

onto the bolts well past the location of the leveling nut and top nut in the test and backed off by 

one worker using an ordinary wrench (without a cheater bar). The threads are considered 

damaged if more than minimal effort is required to turn the nut. If there is no damage to the 

anchor rod or nut during this test, they may be used in the foundation. If there is damage to the 

threads or an inability to attain at least the verification torque, the lot of anchor rods should be 

rejected. 

Though this testing may not be practical on small projects, it is recommended where 

economically justifiable on larger projects. 

TABLE 8 

Nut Rotation for Turn-Of-Nut Pretensioning

Nut Rotation from Snug-Tight Condition a, b, c 

Anchor Rod Diameter, in*. F1554 Grade 36 F1554 Grades 55 and 105 

A615 and A706 Grade 60 

<1 1/2 1/6 Turn 1/3 Turn 

>1 1/2 1/12 Turn 1/6 Turn 

a. Nut rotation is relative to anchor rod. The tolerance is plus 20 degrees. 

b. Applicable only to double-nut-moment joints. 

c. Beveled washer should be used if: a) the nut is not in firm contact with the base plate; or b) the outer 

 face of the base plate is sloped more than 1:40. 

The recommended procedure for installing anchor rods in the foundation is as follows: 

1. Anchor rods should be installed as a group and should be secured against 

relative movement and misalignment, such as with a template set composed of 

rings with nuts on both sides at two locations along the length of the anchor rods. 

One of the plates or rings is usually above the top of concrete and is reused as a 

template, see Figures 13 and 14. 

33 
2. The template set (or other device) with anchor rods should be secured in its 

correct position in accordance with the drawings. 

3. The concrete should be placed and cured. 

Figure 13. Four Anchor Rod Group in a Template. 

Note Top is Galvanized. 

Figure 14. Template Secured to the Forms to Ensure Proper Alignment. 

Note Anchor Rod Threads Taped to Prevent Contamination by Concrete. 

4. If a top template is above the concrete surface, it may be removed 24 hours after 

placing the concrete. 

5. The exposed part of the anchor rods should be cleaned with a wire brush or 

equivalent and lubricated with beeswax or toilet-ring wax. 

34 
6. After at least 24 hours, the anchor rods should be inspected visually to verify that 

there is no visible damage to the threads and that their position, elevation, and 

projected length is within the tolerances of the AISC Code of Standard Practice 

for Steel Buildings and Bridges; and that the misalignment from vertical is no 

more than 1:40. It is good practice to use a steel or wood template with the hole 

pattern to check the base of the post and the anchor rods. The nuts should be 

turned onto the rods well past the elevation of the bottom of the leveling nut and 

backed off by one worker using an ordinary wrench without a cheater bar. 

7. Once the concrete has reached sufficient strength, anchor rods are ready to be 

subjected to erection loads. 

6.9 Procedure for Anchor Rod Tightening and Follow-Up Retightening 

Anchor rod joints require some level of pretensioning. Only installation of double-nut-moment 

joints is covered in this section since single-nut joints are generally not recommended for large 

cantilevered structures. Requirements for fatigue-loaded, threaded-shear-and-uplift joints may 

be derived from the installation requirements of double-nut-moment joints. 

The "turn-of-the-nut" method is primarily relied upon to achieve a certain pretension between 

the double nuts of the anchor rods. Although torque is a poor way to install bolts and anchor 

rods, it is the only alternative for defining snug-tight conditions, inspection, and retightening. 

Lubrication of the threads of the anchor rod, the threads of the nut, and the bearing surface of 

the nut is required for proper installation. Beeswax and toilet-ring wax have been shown to 

provide good lubrication. In this document, the snug-tight condition for anchor rods is defined 

as nuts tightened to a torque between 20 and 30 percent of the verification torque computed 

using the following equation: 

 Tv = 0.12dbFI

Where 

 Tv = verification torque (inch-kips or kN-mm) 

 db = nominal body diameter of the anchor rod (inches or mm) 

 FI = installation pretension (kips or kN) equal to 50 percent of the specified 

minimum tensile strength of F1554 Grade 36 rods, and 60 percent for the rest 

of threaded fasteners. 

Research by Till and Lefke has shown that a value of 0.12 in this relationship is adequate for 

common sizes and coatings of anchor rods. (Note: the torque in "in-kips" can be multiplied by 

83.3 to get ft-lb and the torque in kN-mm can be multiplied by 0.73 to get ft-lb). 

Very large torque may be required to properly tighten anchor rods greater than 24 mm (1 inch) 

in diameter. A “cheater bar” such as a pipe or extension handle as much as 3 meters (10 feet) 

long may be required for the torque wrench. For snugging the leveling nuts, an open-end 

wrench with a 3 meter (10 feet) long pipe or extension handle will typically suffice. Tightening 

the top nuts for anchor rods greater than 1 inch in diameter may require either of the following: 

35 
♦ A hydraulic torque wrench (Figure 15) or 

♦ A box end "slug" or "knocker" wrench with a 3 meter (10-ft), long pipe or extension 

handle. 

Figure 15. A Hydraulic Torque Wrench Tightening Anchor 

Rod Nuts to Achieve Needed Rotation. 

The box end wrench may be moved by impact with a sledgehammer or by the efforts of several 

workers. Inadequately tightened bolts can lead to fatigue failures and further loosening of the 

nuts under cyclic loading. A less likely outcome of failure to follow the tightening procedure is 

over-tightened rods and associated plastic deformation and stripping of the threads, which may 

require removal and replacement. 

The following steps provide a recommended anchor bolt installation and tightening procedure: 

1. The proper position of the anchor rods and the proper hole pattern on the post 

are verified (preferably with a template). 

2. It should be verified that the nuts can be turned onto the rods well past the 

elevation of the bottom of the leveling nut and backed off by one worker using an 

ordinary wrench without a cheater bar. 

3. If threads of anchor rods were lubricated more than 24 hours before placing the 

leveling nut or have been wet since they were lubricated, the exposed threads of 

the anchor rod should be relubricated. Leveling nuts should be cleaned, threads 

and bearing surfaces lubricated. 

4. The leveling nuts are placed on the anchor rods and made level. 

5. Leveling nut washers should be placed. 

6. Next, the post or end frame is brought in and positioned with a crane. 

36 
7. The post or end frame is plumbed or the base plate leveled (as shown on the 

erection drawings) and the anchor rods are tightened. The following is the 

installation sequence for double-nut-moment joints using the "turn-of-the-nut" 

method of pretensioning. 

8. Top nut washers should be placed. 

9. Threads and bearing surfaces of the top nuts should be lubricated, placed, and 

tightened to the snug-tight condition in a star pattern. 

10. Leveling nuts should be tightened to the snug-tight condition in a star pattern. 

11. At this point, the installation crew should verify if beveled washers are necessary. 

Beveled washers may be necessary under the leveling or top nut if any face of 

the base plate has a slope greater than 1:20 and/or any nut could not be brought 

into firm contact with the base plate. If any beveled washer is required, the 

installation crew should disassemble the joint as necessary, add the beveled 

washer(s) and retighten (in a star pattern) to the snug condition top and leveling 

nuts. 

12. Before turning, the reference position of the top nut in the snug-tight condition 

should be marked with a suitable marking on one flat with a corresponding 

reference mark on the base plate at each bolt. Top nuts should be turned in 

increments in a star pattern (at least two full tightening cycles) to the nut rotation 

specified in Table 8. After tightening, the nut rotation should be verified. 

13. The load may be released from the crane. 

14. A torque wrench should be used to verify that a torque at least equal to the 

computed verification torque, Tv, is required to additionally tighten the leveling 

nuts and the top nuts. An inability to achieve this torque should be interpreted to 

indicate that the threads have stripped and should be reported to the Engineer of 

Record. 

15. After at least 48 hours, the torque wrench should be used to verify that a torque 

at least equal to 110 percent of the verification torque, Tv, is required to 

additionally tighten the leveling nuts and the top nuts on the anchor rods. An 

inability to achieve this torque shall be interpreted to indicate that the threads 

have stripped and should be reported to the Engineer of Record. 

16. The nuts on the anchor rods should be prevented from loosening unless a 

maintenance plan is in place to verify at least every 4 years that a torque equal to 

at least 110 percent of the verification torque, Tv, is required to additionally 

tighten the leveling nuts and the top nuts. Jam nuts or other locking devices may 

be used to prevent nut loosening. 

Tack welding the nut to the anchor rod on the unstressed (top) side of the top nut has been 

used successfully to prevent loosening or to prevent theft of the nuts, although this would not be 

allowed under AWS D1.1 and therefore cannot be recommended. If it is used, only ASTM 

Fl554 Grade 36 or Grade 55 rod, or Grade A 706 reinforcing bar should be tack welded. Under 

37 
no circumstance should any nut be tack welded to the washer or the base plate nor should the 

leveling nut be tack welded. 

7.0 MANAGEMENT OF INVENTORY 

Collection of inventory information and the ability to organize and categorize the inventory is 

paramount for an ancillary structure inspection program. This section details collection of such 

information and development of a useful database. 

7.1 Collection of Inventory Information 

One of the biggest problems in inspection of ancillary structures is the lack of information. 

Rarely are the structures numbered for easy identification. Historical records such as as-built 

plans, maintenance repairs, and installation of new sign panels are hard to find. Only now are 

many states beginning to assign structures numbers during design and/or fabrication similar to 

bridge structures. Such records are very important due to the many changes to the design 

specifications of sign structures over the years. Another problem is that fabricators have 

substituted design drawings with their own shop drawings. While this is an acceptable practice, 

it adds another layer of documentation that is many times lost. 

For these reasons the initial collection of inventory information on ancillary structures is critical. 

Key pieces of information include route, milepost, GPS coordinates, route association (if not on 

mainline), county, town, etc. Photos and sign measurements are important to help identify 

structures, as seen in Figure 16. The following section on database development gives a 

complete listing that has been used in New Jersey for inventory purposes. 

Figure 16. Inspector Measures Sign Panel During Inventory/Inspection Operation. 

7.2 Database Development 

38 

The large amount of data collected to properly inventory a sign structure warrants a 

sophisticated database that can sort and prioritize according to structure type, age, location, 

material, ratings and repair priorities. The goal is to have a database useful to the field 

inspector, program manager, and maintenance and repair personnel. Each can then draw on 
their desired information. The database can be a simple spreadsheet but usually involves a 

more sophisticated program like Microsoft Access or Oracle. 

7.3 Example Inventory Checklist 

The checklist below is referenced from the New Jersey Department of Transportation Overhead 

Sign Database Program. These are items deemed important to that particular agency, and will 

of course vary somewhat with individual State needs. Many items involve the physical location 

of the structure, the personnel involved with the inventory/inspection, specifics about the 

structure itself, important dimensions and attachments. 

 NJDOT Required Inventory / Inspection Information 

• Date Inspected 

• Previous Inspection Date 

• Inspection Type 

• Cycle Number 

• Recommended Inspection Frequency 

• County Code 

• Municipality Code 

• Latitude/Longitude 

• Route 

• Milepost 

• Location Description 

• Traffic Control Requirements 

• Contract Number 

• Consultant Firm Name 

• Consultant Project Manager 

• Consultant Team Leader 

• Confirming Registered PE 

• Structure Name 

• Structure Configuration 

• Number of Truss Sections 

• Material Type 

• In Service Status and Date 

• Overall Span Length 

• Minimum Vertical Clearance 

• Left and Right Lateral Clearance 

• Number of Traveled Lanes 

• Number of Signs 

• Area of each Sign 

• Installation Year 

• Plans Available? 

• Walkway? 

• Lighting? 

• Modification since construction 

• Damage Reports 

• Element Ratings 

39 

• Element Repairs 
7.4 Inventory Numbering 

An inventory-numbering scheme is required for all ancillary structures. The inventory number is 

usually the key piece of data that any database relates to. It can be sequential along a route, 

and contain information relevant to location such as County and Town Coding. It is highly 

recommended that after an ancillary structure number is assigned the number be immediately 

stenciled onto the existing sign. Documentation should flow from the field to the sign designer 

so that any new structures would not be assigned that specific inventory number. 

One problem with sign stenciling is that many structural supports are on shoulders that are 

targets for roadway grime, salt spray and snowplows. Proper positioning of the sign number 

should consider these effects. The stencil can be placed above the spray of salt or on the 

backside of the structure. Another option might be to stencil the sign bridge instead of the 

supporting tower members, or to stamp the number in with metal stamps. 

8.0 INSPECTION VARIABLES 

8.1 Types of Inspections 

There are several inspection types depending on the circumstances of the sign structure. 

These inspection types follow those typically performed for bridge inspections. 

8.1.1 Initial Inspection 

This inspection should take place shortly after the sign structure is constructed. It is common 

for bolts on sign structures, shortly after installation, to become loose and should be rechecked 

within 60 days after construction is complete. 

8.1.2 Routine 

This can simply consist of a ground level inspection with no attempt to close traffic lanes. This 

type of inspection is recommended during the first phases of a sign structure inspection 

program to obtain inventory information and quickly look for deficiencies. However, since many 

structural deficiencies such as weld cracks in the overhead truss cannot be identified from a 

ground level inspection, this type of inspection is not recommended to occur normally in 

subsequent inspection cycles. However, as stated in the ‘Traffic Control’ portion of these 

guidelines cyclic ground level inspections may supplement an In-Depth inspection due to severe 

traffic restrictions. 

8.1.3 In-Depth 

This type of inspection is recommended as a typical inspection of a sign structure. The 

inspection will be ‘Hands-On’ as discussed in the following section. 

8.1.4 Interim Inspection 

40 

This would be recommended by the Inspector if a sign structure is found to have deficiencies or 

other problems that require more frequent inspection than the typical inspection frequency. An 

Interim Inspection might also be required after temporary repairs are made to the sign structure. 

For example, some measures are immediately taken when cracks are found in the overhead 
sign truss. This may be simply removing the sign panels to reduce wind load, installation of a 

dampener, or actually completing repairs such as the use of fiber composite material to 

temporarily restrain the cracked connection. 

8.1.5 Damage Inspection 

This inspection is provided after a sign is damaged. This could include traffic impact on the 

post, an over height hit of the truss or sign panels, etc. 

9.0 INSPECTION FREQUENCY 

Determining the frequency for ancillary structure inspection is dependent on several factors. 

One is material type. For example, aluminum truss type span structures have shown increased 

problems due to fatigue deficiencies. High strength anchor rods have been more problematic 

than mild steel. Frequency can also be based on structural redundancy. Cantilever sign 

structure supports only have one main support instead of two or more with span type structures. 

Sign structures associated with another structure such as a bridge-mounted sign may be 

inspected as the bridge is inspected during a normal two-year frequency. Many owners are 

initiating sign structure programs and determining frequency after the first cycle is complete and 

deficiencies can be categorized. Another previously discussed factor is traffic control and the 

problems associated with access. 

Some guidelines for inspection frequencies are as follows: 

Material Issues: Since it has been determined that aluminum sign bridges are 

problematic, it is recommended that a two-year frequency of in-depth inspections 

be conducted. To determine if material issues are relevant prior to a full-scale 

inspection program is set in motion a sample project that inspects 10% of the 

structure inventory may be prudent. 

Redundancy Issues: For cantilever and other non-redundant structures a fouryear frequency is recommended. 

Typical Sign Bridges: A typical two tower, two or four post sign bridge with a 

steel superstructure need only be inspected hands-on every six years. Routine 

or ground inspections can be conducted more frequently to check corrosion of 

posts or connection problems. 

Traffic Issues: If ‘severe’ restrictions exist, as discussed in the ‘Traffic Control’ 

section of these guidelines, frequencies stated above can be extended but 

supplemented by routine ground inspections. 

10.0 INSPECTION PRIORITIES AND PLANNING 

The ancillary structure inspection process should not proceed until a structure inventory has 

been completed. Only then can proper planning take place. Many State Departments of 

Transportation have started their structure inspection program using the following strategy: 

1. Perform field reconnaissance and collect inventory information 

2. Perform a random sampling inspection project of perhaps 10% of total inventory 

41 
3. Based on findings of sample project, prioritize and continue full inspection 

program. 

Example Priorities 

• Aluminum sign bridges 

• Sign Bridges with long span 

• Non Redundant cantilever sign structures 

• Sign Structures greater than 20 years old 

• Sign Structures where sign panel sizes exceeds those originally designed for. 

11.0 REQUIRED RESOURCES 

11.1 Suggested Personnel Requirements 

Inspection of ancillary structures is not required by Federal Regulations, nor are there any 

requirements for those person who conduct such inspections. 

Inspection of ancillary structures has similarities to highway bridges but also some special 

circumstances that should be addressed. The qualifications for bridge inspection personnel as 

given in the National Bridge Inspection Standards (23 CFR 650), are summarized below with 

suggested special modifications for ancillary structures. 

Program Manager – The program manager is in charge of the scoping, scheduling, cost control, 

and quality assurance. Minimum qualifications should be a Professional Engineer or have a 

minimum of 10 years of experience in structures inspections in a responsible capacity and have 

completed comprehensive training based on the Guidelines for the Installation, Inspection, 

Maintenance and Repair of Structural Supports for Highway Signs, Luminaires and Traffic 

Signals. 

Team Leader – Have qualifications specified for Program Manager or have a minimum of 5 

years of experience in structure assignments in a responsible capacity or NICET Level III or IV 

certification in Structure Inspection and have completed a comprehensive training program 

based on the Guidelines for the Installation, Inspection, Maintenance and Repair of Structural 

Supports for Highway Signs, Luminaires and Traffic Signals. In addition, the Team Leader 

should be trained in work zone traffic control such as the NHI Course 38003 – Design and 

Operation of Work Zone Traffic Control. 

An inspection team will usually consist of a Team Leader and an Assistant. Assistant Team 

Leader qualifications can be project specific. Due to the extent of welded members found in 

most ancillary structures, it is desirable for at least one team member to have experience in 

visual weld inspection as well as training in locating and recognizing fatigue cracking. 

All inspection personnel should be able to physically perform the work. Although bucket trucks 

are typically used to access the sign bridge, an adequate in-depth inspection cannot be fully 

performed from the bucket and some climbing will be required. 

42 
11.2 Tools and Equipment 

Each inspection team should be fully equipped to perform the structural inspections. Additional 

equipment may be needed since sign structure inspectors routinely make minor repairs. The 

reason minor repairs may be attempted during the inspection process is to avoid another work 

zone setup to perform a minor repair. Such minor repairs may include bolt tightening, 

replacement of fasteners such as cotter pins, and paint touchup, along with replacing missing 

pole caps, anchor rod nut covers and hand hole covers. 

The list below is what would be considered as ‘Tools of the Trade’ for the sign structure 

inspector. 

♦ Work-Zone protection and traffic control equipment, including signs, traffic cones and 

flags (in compliance with the MUTCD and local requirements). 

♦ Personal safety equipment, including hard hats, reflective high-visibility vests, 

goggles, face shields, harnesses (or belts), and lanyards. (All OSHA approved). 

♦ Basic access equipment, such as a step ladder, extension ladder, and rope 

♦ Tools for inspection, including chipping hammers, pocket knives, screwdrivers or 

awls, magnifying glass, magnet, flashlights, mirrors. The hammer is an excellent tool 

for testing anchor rods. The mirror is for inspecting circumferential welds while 

climbing the truss. A magnet can confirm whether the material is steel or aluminum, 

as aluminum is nonmagnetic. 

♦ Tools for measuring, such as a plumb bob, levels, folding rulers, tapes, calipers, 

thickness gauges 

♦ Wrenches, allen wrenches, screwdrivers for removing access panels and bolt covers 

♦ Torque wrench for bolt tightening or checking bolt tension 

♦ Digital camera for documentation 

♦ Shovel and brush cutters 

♦ Marking utensils such as lumber crayons or keel, paint sticks, soapstone, center 

punch 

♦ GPS-recommended since many signs look similar, even sign panels, and are 

routinely replaced without complete notification to all parties. 

♦ Electronic device for measuring vertical clearances is recommended. 

♦ Equipment to number the signs, either paint stenciling, adhesive tape, paint markers, 

etc. 

♦ Non-Destructive test equipment such as ultrasonic testing, dye penetrant, or 

magnetic particle. 

♦ Remote cameras for high mast lighting 

♦ Bucket truck, see explanation below 

While free climbing from the shoulder or with ladders, Figure 17, can access many sign 

structures, the most typical way the sign structure is accessed is by use of a vehicle mounted 

access bucket, Figure 18. These vehicles are commonly used by cable and telephone 

companies and are readily available for rent. For most ancillary structures a 30’ boom is 

sufficient. Access vehicles must be operated in accordance with required safety procedures. 

43 
Figure 17. Inspector Climbing Structure. 

 

Figure 18. Bucket Truck-Most Common Way to Access Sign Structure. 

11.3 Traffic Control 

One of the most difficult challenges for the inspection and evaluation of overhead sign 

structures is that of access for inspection personnel. This challenge arises from the need to 

satisfy Maintenance and Protection of Traffic (MOT) safety requirements while controlling costs 

within acceptable limits. Such access strategies include night work, mobile lane closures, and 

other innovative methods for short-term lane closures. At the heart of the ability to gain 

inspection access is determination of what areas of these structures are most critical and how 

often should they be inspected. 

44 
It is suggested that a cost benefit ratio be developed for each overhead sign inspection project 

that considers inspection access, inspection detail, MOT cost and overall safety. Some 

suggestions for each are presented below with the key determining factor defined as the lane 

closure restrictions. All suggestions comply with the basic requirements discussed in the 

‘Manual for Uniform Traffic Control Devices’ (MUTCD). 

It is recommended that night work be a last resort in planning an inspection program. The 

small fatigue cracks in a typical sign truss are difficult enough to spot during daytime inspection 

hours. If inspections are performed at night, adequate lighting must be provided. Below are 

several considerations in developing a sign inspection strategy driven by closure restrictions. 

Minimal Lane Closure Restrictions 

An example of minimal restrictions would be the allowance of double lane closures during 

normal work hours between 8 AM and 5 PM. For this scenario it is suggested that conventional 

stationary type MOT be used. The closure, since of a temporary nature, should be easily 

deployed and removed. Typical MOT equipment would be a fabric sign conforming to NCHRP 

350. Fabric signs allow easy deployment over rigid metal. Also, cones should be used over 

barrels or barricades again to allow easy setup and removal. If more substantial MOT 

equipment is required means other than a stationary setup should be investigated. Under these 

lane closure restrictions a complete full hands on inspection should be scheduled as 

recommended in the ‘Inspection Frequency’ section of this document. 

Moderate Lane Closure Restrictions 

An example of a moderate closure restriction would be limited closure time such as a 10 AM to 

2 PM window for a double lane closure. A conventional stationary closure could be considered 

if a full 8-hour window can be scheduled using single lane closures during the morning and 

afternoon hours. An efficient inspection day might allow for a morning single lane closure 

encompassing several sign structures that can be expanded into a double lane closure at 10 

AM. It is recommended that under moderate lane closure restrictions a full hands on inspection 

could be completed per the frequency recommended in the ‘Inspection Frequency’ section of 

this document. 

Severe Lane Closure Restrictions 

An example of a severe lane closure restriction would be no daytime double lane closures 

allowed. In this case, the best option would be a mobile night time closure. To reduce the risk 

of missing deficiencies during the night time inspections as much of the work as possible should 

be completed during the day using single lane closures. An example would be the use of single 

left and right lane closures during the day to inspect the post, base, foundation and truss to post 

connections. The night time work would therefore be restricted only to the interior traveled 

lanes focusing just on the truss welds and sign connections. Instead of a full hands on 

inspection with frequencies recommended in the ‘Inspection Frequency’ section of these 

guidelines, a modified strategy might be needed. This may be an alternate cyclic combination 

of hands on and shoulder inspections to minimize the full lane closures. 

45 
11.4 Safety 

It is highly recommended that every ancillary structure inspection program have a detailed 

safety plan submitted prior to work commencing. Sign structure inspections are one of the most 

hazardous types of structural inspections. They usually occur adjacent to live traffic. The sign 

structures are many times located at the ‘gore’ or exit areas of high speed roads where work 

zone safety setups can be extremely difficult to setup. In addition, it is routine that the inspector 

‘climb’ the structure, which are complicated due to angled diagonals and slippery structural 

members. 

When climbing a sign or other ancillary structure a two lanyard system offers the best protection 

with one lanyard always secured to the structure, see Figure 19. Good gripping boots similar to 

ones a mountain climber would use are recommended. To perform a climbing inspection 

everything worn or carried by the inspector must be securely attached to him/her so nothing can 

drop or hang below the bottom of the structure. The reporting of inspection findings may be 

handled by use of a radio attached to the inspector through which findings are relayed to a 

notetaker on the ground. Since the traveling public may be concerned when observing 

someone climbing a sign structure, some states place a variable message sign stating “Workers 

Overhead” as informational aid. 

Listed below are typical contents of a safety plan: 

1. Safety Plan Officer for Inspection firm 

2. Safety Organization 

3. Safety Incident Report Procedures and Forms 

4. Fall Safety Specifications 

5. Operation of Bucket or lift truck guidelines 

6. Hospital Locations 

7. Latest Manual of Uniform Traffic Control Devices (MUTCD) 

8. Specific work zone traffic setups for ‘gore’ areas 

9. Mandatory personal safety equipment 

10. First Aid Kit 

46 
Figure 19. Inspector Uses Double Lanyard System. 

12.0 THE INSPECTION PROCEDURE 

With a developed inventory and strategy for inspection, the actual inspection procedures can 

then be reviewed and implemented. 

12.1 Pre-Inspection Review of Available Materials (Desk Review) 

The pre-inspection review of information, otherwise referred to as a desk review, should be 

conducted prior to any ancillary structure inspections. All historical records should be located 

and reviewed such as as-built design drawings, prior inspection reports, shop fabrication 

drawings, and previous notes on traffic control. If not already developed a structure folder 

should be developed containing these items. 

12.2 Inspection Nomenclature 

Like any structural inspection, orientation and proper nomenclature are important. 

Nomenclature as to overall structure orientation usually is related to the direction of roadway 

travel, though details vary from state to state. As an example, Figure 24 shows New York 

State’s nomenclature for the orientation of overhead sign structures. The following sections 

provide typical nomenclature for ancillary structures. 

12.2.1 Sign Bridge 

A structure supporting sign panels or other devices such as variable message signs that span 

over the traveled way with supports on both sides of the roadway. May also be referred to as a 

Span Structure. Detailed nomenclature for the various parts is given in Section 12.2.6. 

12.2.2 Cantilever Sign Structure 

47 

A structure that extends over traffic and has a support on only one side of the roadway. The 

specific components are very similar to those of a sign bridge as given in Section 12.2.6. 
12.2.3 Mast Arm Structure 

A structure that cantilevers over traffic with a single mast arm. This is different than a cantilever 

sign structure that may have a truss or dual arm as the cantilever support for signs or other 

attachments. A mast arm usually supports small signs or traffic signals. The primary 

components are the foundation, base plate, anchor rods, pole to base plate connection, pole, 

mast arm to pole connection, and mast arm. 

12.2.4 Signal Supports 

A structure, usually a mast arm type, which supports traffic signals. The primary components 

are the foundation, base plate, anchor rods, pole to base plate connection, pole, mast arm to 

pole connection, and mast arm. 

12.2.5 Light Poles 

A structure supporting lighting, such as a high mast lighting tower. The primary components are 

the foundation, base plate, anchor rods, pole to base plate connection, pole, and luminaire. 

High mast poles also have a luminaire raising device and generally a slip joint (or more) in the 

post. 

12.2.6 Detailed Nomenclature 

The nomenclature for the various components of overhead sign structures is given below and 

shown in Figures 20, 21, and 22. The base components for the sign truss are similar to those of 

other ancillary structures. 

Truss – superstructure that is composed of truss members. These can be tubular or angular. 

Chords – The main horizontal members of the truss. 

Diagonals – The diagonal members of the truss. 

Splice – Usually referred to as the connection between the truss chords. May also occur in long 

mast arms and high poles. 

Catwalk – The walkway used by maintenance personnel, usually located in front of the sign. 

Foundation – The portion of the sign structure that directs the load into the ground. Usually 

constructed of concrete pedestal on pile, spread or caisson foundations. 

Anchor Rod – The rods that connect the sign structure base to the foundation. 

Base Plate – The plate used to connect the post base to the foundation. 

Post or Tower – The vertical supporting members of a sign structure. 

48 
Figure 20. Nomenclature Associated with Sign Bridge. 

Note: Use of grout pad is optional.

49 
Figure 21. Nomenclature for Ancillary Structure Tower Supports. 

50 
Figure 22. Example-Truss to End Frame Connection Nomenclature. 

Truss Seat – The member that supports the vertical load of the truss. 

Handhole – An opening in the sign structure post for access. Usually located 3’ above the base 

plate. 

U-bolts – Bolts shaped like the letter ‘U’ used to attach sign framing brackets to the sign truss. 

Saddles – Bearings that support the chords of truss structures. 

Shim Plates – Metal plates used to account for elevation differences in tower to truss supports. 

Sign Panels – Sign Panels are usually attached to the structure via a Vertical Support Angle 

(Figure 23). The vertical angle is connected to Horizontal Support Angles. Finally the panel 

itself is connected to the angle with Sign Clips. Sign panels can be made as one continuous 

unit or partial units joined together with Backing Strip connections. 

51 
Figure 23. Sign Panel Support Components. 

12.2.7 Orientation of Members 

Members for the sign truss usually follow truss nomenclature. That is, panel points a re labeled 

across the truss and members are labeled according to their beginning and ending panel points. 

Panel points are labeled left to right as viewed from the front. Chords and Towers are labeled 

as ‘Front’, ‘Back’, ‘Upper Front’, ‘Lower Front’, ‘Upper Back’, and ‘ Lower Back’. Instead of 

compass directions signs are normally labeled ‘Near Side’ and ‘Far Side’ based on the direction 

of travel. 

52 
Figure 24. Orientation of Overhead Sign StructuresNew York State Department of Transportation. 

12.3 Sequence of Inspection 

The inspection of ancillary structures requires a ‘hands on’ approach. To check for structural 

deficiencies it is necessary for the inspector to access all critical locations, often by climbing. 

The inspector wears a safety harness with two lanyards so that he/she is tied off to the structure 

at all times. The inspector carries many tools such as electronic and tape measuring devices, 

wrenches to tighten loose hardware, marking tools and mirrors to see the underside of welds. 

Nondestructive testing (NDT) equipment may or may not be required. Figure 25 shows a visual 

inspection of a chord splice connection for an overhead sign truss. 

For structures such as signal supports it is usually possible to conduct the inspection from a 

bucket truck with minimal traffic disruption. High mast lights may require specialized 

techniques, which are discussed in Section 12.3.3. 

53 
54 

Figure 25. Hands on Inspection of Overhead Signs. 

12.3.1 Sign Structures 

A typical hands on inspection of a sign structure starts at the foundation and works skyward. 

The foundation, typically made of concrete, is checked for cracks, spalls and other signs of 

deterioration. Many times drainage pathways in the foundation become blocked with debris not 

allowing water to escape from the inside of the post. Many structures have grout pads to 

support the post base. These are often susceptible to deterioration. It is important to check 

historical documents to see if grout pads were part of the original design. If they were not, many 

times existing deteriorated pads can be removed. 

Post to foundation connections usually consist of anchor rods that transfer the load from the 

structure post to the foundation. Anchor rods can become corroded over time and fail under 

fatigue loading. Many anchor rods initially installed might have been too short or too long. If too 

short, a coupler may have been used that cannot transfer the load. Many long rods are cut or 

flame torched which may change the mechanical properties of the rod. By ‘sounding’ the 

anchor rods with a hammer, an inspector can check both the rod and the surrounding 

foundation. 

Anchor rod nuts should be checked for tightness and general condition. Loose leveling nuts as 

well as top nuts can lead to load redistribution and overstressing of anchor rods. Nuts should 

be hammer sounded or checked using a large wrench. 

The base plates that the anchor rods go through and support the post base should be checked. 

Many base plates are found to be broken or warped. Inadequate drainage has also led to 

advanced corrosion. 

The post to base plate weld should be examined for any cracking. Cracking may also be found 

at the termination of stiffener plates. Close inspection may be required to locate any cracks. All 

cracks found during the inspection should have their beginning and end points marked on the 

structure along with the date of inspection using a paint stick. 
An important aspect in the inspection of the support posts are the handholes. The handholes 

themselves, cut into the post, can prove to be areas of weld crack initiation. Handholes allow 

access for inspectors to see the inside of the post. Much noted corrosion of sign structure posts 

has occurred inside the post as water and debris accumulate to form a corrosive environment. 

A quick look inside a handhole, usually located 1 meter (3 feet) above the base, can provide 

instant feedback on potential corrosion. If there are no handholes a thickness meter (D-meter) 

should be used to check critical areas for reduced section area. Additional problems with 

handholes are missing covers or those that cannot be removed due to frozen screws. 

The Post/Tower inspection includes identification of proper ventilation to remove any buildup of 

condensation and a general rating of the tower condition. Posts are frequently found with 

missing top caps that keep rain out. Many steel posts are galvanized and over time some of the 

coating begins to wear. Another consideration is plumbness of the post, which could reveal 

foundation problems, past vehicular impacts or initial erection errors. Especially for out of plumb 

posts, the vertical clearance of the sign over the traveled way should be checked. 

The Post/Tower to truss connections should be checked for missing fasteners or misalignment. 

Span or bridge structures often have saddles and U-bolts at the truss to post connections. 

These should be examined for missing or loose nuts and cracked castings. Cantilever trusses 

are generally connected with high strength bolted flange connections. These should be 

examined for fit-up and loose or missing bolts. 

Once the Post/Tower is inspected the process moves to the horizontal truss or mast arm. Many 

truss members have welded connections that need to be checked. Failed welds in aluminum 

structures have been a major source of concern. It is very hard to access these welds and may 

involve the use of climbing the truss, an aerial lift device such as a bucket truck, and special 

tools such as mirrors. However, all areas must receive an arm’s length inspection if cracks are 

to be found. 

Sign trusses are usually fabricated into smaller sections and erected at the site. The truss 

chord connection is the critical connection between these sections. A flanged splice connection 

may contain both bolted and welded connections. Since chords are critical truss members their 

connections are critical as well. Connection fit-up, loose and missing bolts, and weld cracks 

should be areas of concentration during the inspection. 

Sign Panels should be inspected while the truss is undergoing an inspection. Many sign panel 

fasteners become loose over time. Inspectors are routinely asked to hand tighten these 

fasteners to avoid another lane closure for such a small maintenance item. A large problem in 

many states is the use of larger sign text fonts, which result in larger sign panels. This can be 

dangerous if the original structural designer did not account for such changes. Larger sign 

panels will result in more wind loading on the structure. An inspector should also be aware of 

anything mounted on a sign structure that could increase the wind load. The area of sign 

panels and other attachments should be noted so they can be compared to original design 

conditions. 

After the aerial inspection of all structural members is complete the inspection should proceed to 

any supplemental elements such as walkways, also referred to as catwalks, electrical 

components, and other elements that do not comprise the actual structural system. 

55 
12.3.2 Mast Arm Structures and Signal Supports 

The inspection of mast arm structures and signal supports proceeds generally the same as for a 

sign structure, working from the base on up, see Figure 26. For many of the mast arm and 

signal supports, the anchor rod nuts are covered by a cap. These must be removed to examine 

the top nuts, even if removal results in damage. Damaged caps should be reported for future 

replacement, or the inspection team may be supplied with spares for installation. 

Figure 26. Inspection of a Mast Arm Structure. 

If hand hole covers cannot be removed to check for internal corrosion, an ultrasonic thickness 

gauge should be employed to check the pole thickness and possible internal corrosion. 

The mast arm to pole connection should be carefully examined. A wide variety of post to arm 

connections are used. Loose and missing bolts, misaligned fasteners, and weld cracks are 

often found (Figure 27). Mast arm to post connections where the post connection consists 

simply of two side plates welded to the pole with a face plate that accepts the bolted arm 

connection have been found especially susceptible to cracks at the plate to post welds. 

56 
Any splices in the mast arm should be inspected, and the inspection may include the signal to 

mast arm connection and any signs or panel connections to the arm. Where these areas are to 

be inspected, traffic control is normally required to allow access from a bucket truck. 

12.3.3 Light Poles and High Mast Lights 

Inspection of luminaire supports, including high mast lights, generally proceeds from the ground 

up as for sign and other structures. Access for inspection can generally be gained by use of 

bucket trucks. However, for high mast lights sufficiently long booms to reach all parts may not 

be available and it is often impractical to access the location of the light pole with these very 

large bucket vehicles. Alternative means of inspection “access” are discussed later in this 

section. 

For luminaire supports of modest height, say under 40 feet, anchor bolt inspection may require 

removal of bolt covers. Because these poles may oscillate however slightly in even modest 

winds, it is recommended that anchor bolt nuts be checked at both the beginning and end of the 

inspection. Leveling nuts should also be checked if accessible. Figure 28 shows loose leveling 

nuts on a high mast structure. 

57 
Figure 28. Loose Leveling Nuts on a High Mast Structure. 

(Note: Top Nuts on Chairs Out of Photo) 

Hand hole or other access covers near the base of the pole should be removed and the interior 

examined for moisture and corrosion. High mast lights usually have the apparatus for lowering 

the luminaire ring located inside the base of the pole. Checking the operation of this system is 

not normally part of the structure inspection. However, the apparatus is normally supported by 

steel members connected to the inside of the pole and these should be examined for loose 

connections and weld cracks and defects as these can migrate into the pole. 

High poles may consist of more than one section. These are “spliced” by use of a slip joint, as 

shown in Figure 29, in which the upper segment simply slips over the lower segment. The 

condition of this joint should be examined for cracks, deformation along the base of the 

connection, and rust stains. Slip joints, partly because of the tendency of water to be drawn into 

them by capillary action, sometimes experience corrosion between the two segments. This can 

lead to the build up of pack rust, particularly in weathering steel poles, that may lead to a vertical 

crack emanating from the bottom of the upper pole segment. 

58 
Inspection of the luminaire ring is not usually part of the structural inspection. However, visual 

observation of any defects should be recorded for future inspection by appropriate personnel. 

Some defects noted in the luminaire ring may relate to mechanical or structural components and 

should be examined further. Figure 30 shows a misaligned luminaire ring which was found to 

be the result of a broken support cable. 

Figure 30. Misaligned Luminaire Ring. 

Due to the difficulty of accessing pole splices and luminaire rings, particularly in the high poles 

that are now common, inspection techniques other than arms length inspection are normally 

used for these areas. Inspection is normally visual and is made using a pair of binoculars of at 

least ten power magnification or a telescope such as a shooter’s spotting telescope. 

Telescopes offer higher magnification, with the ability to identify smaller cracks. Several efforts 

have also been made to develop a remotely operated inspection device that can climb the pole 

Figure 29. High Mast Pole Slip Joint. 

59 
while carrying a video camera and possibly other inspection equipment. Figure 31 shows one 

such device, developed by the Virginia Transportation Research Council. At present, these 

devices are difficult to maneuver and position and require increased inspection time. With 

continued development; however, they may become a tool for routine inspections, particularly of 

slip joints. 

Figure 31. Remotely Operated Inspection Device. 

12.4 Non Destructive Testing 

Non Destructive Testing (NDT) is an important tool used for the inspection of ancillary 

structures. While visual inspection is the primary inspection method, it cannot detect all 

structural deficiencies. Examples include small fatigue cracks in welds, corrosion occurring on 

the interior of the structural element, and cracked anchor rods. A list of NDT Methods and their 

application to ancillary structures is given below. 

♦ Ultrasonic thickness ‘D meter’ measurements – Probably the most critical NDT for 

ancillary structures since failures have been attributed to interior element corrosion 

that cannot be visually detected (Figure 32). A simple ultrasonic thickness gauge 

can also be used to check anchor rod lengths and for possible fractures. More 

sophisticated ultrasonic flaw detection equipment can be used to examine anchor 

rods for possible cracks or other flaws. A test procedure for anchor rods is contained 

in Appendix B (Figure 33). 

♦ Dye Penetrant Test – Excellent test for exposed welds in non-ferrous materials such 

as aluminum, as well as steel structures. It is usually used to confirm visual 

observation of a crack. Dye penetrant can help distinguish between cracks and 

surface defects such as galvanizing flaws which are crack like in appearance. Dye 

penetrant can only detect surface cracks. 

60 
♦ Magnetic Particle Test – Excellent test of exposed welds in metallic materials such 

as steel, Figure 34. This technique can reveal “near surface” cracks as well as 

surface cracks. 

♦ Eddy Current Test – Used for painted sign structures or aluminum structures to 

detect weld cracks where magnetic particle testing does not function due to lack of 

magnetic attraction. 

It is important that the person conducting the test, as well as the personnel interpreting the test

data, be properly trained in the applied method. Additional qualifications should include both an 

understanding of the theory behind the test and practical experience. All inspection methods 

should be conducted in accordance with applicable American Society for Nondestructive 

Testing (ASNT) procedures, American Society for Testing and Materials (ASTM) standards, and 

American Association of State Highway and Transportation Officials (ASSHTO) specifications. 

Nationally recognized certifications in NDT are provided through ASNT. Since many of the tests 

performed on ancillary structures are fairly standard and specific in nature, certifications in these 

particular tests may by an acceptable alternative to full ASNT certification for those engaged in 

ancillary structure inspection. 

Figure 32. Thickness Measurement at Critical Location of Structure Post. 

61 
12.5 Quality Control Plan 

Every ancillary structure inspection program should include a Quality Control Plan. The plan 

should address consistency in the inspection process and repair recommendations. The plan 

should address personnel qualifications as discussed earlier in these guidelines. It is important 

to remember that ancillary structures are a ‘different animal’ unlike bridges and need to be 

viewed from that perspective. 

Figure 33. Ultrasonic Testing of Anchor Rods. 

Figure 34. Magnetic Particle Inspection of Weld at Post to Base Plate Connection. 

62 
13.0 ELEMENT INSPECTION

Inspection findings are reported in a variety of ways. In keeping with bridge inspection 

methodology a number is normally assigned to structures or their components that represent 

their condition. In order to provide consistency with current bridge inspection reporting, an 

element based inspection reporting system is recommended. 

13.1 Element Definitions 

Each owner should develop an inspection reporting system consistent with their particular 

needs and asset management procedures. Various element level reporting formats including 

PONTIS based systems have been utilized, as illustrated by the examples in Appendices B and 

C. The PONTIS based systems, as presented in Section 14, provide for quantifying both 

elements and the extent of defects. However, they typically do not include nonstructural 

information on “elements” such as vertical clearance or adjacent guard rails that may be of 

interest and not readily available elsewhere. 

The eighteen (18) elements shown in Table 9 are recommended for use in rating Highway 

Signs, Luminaires, and Traffic Signals where a PONTIS based system is not utilized. Note that 

all elements may not be applicable to a specific structure type. 

Table 9 

Element Definitions 

Element Number Description 

S.01 Foundation - This element includes foundation(s) that are 

constructed of reinforced concrete or steel. Inspectors should 

assign ratings based on the overall condition of the foundation 

and its ability to function properly. The condition of grout pads, 

if present, shall also be included in this element. 

S.02 Anchor Rods - This element defines anchor rods, anchor nuts, 

leveling nuts, and washers connecting the column support 

members to the foundation. 

S.03 Base Plate(s) - This element defines the base plates, flanges, 

gusset plates and welds at the connection of the column 

support(s) to the foundation(s). The elements may be painted, 

unpainted, or galvanized. 

S.04 Tower(s) - This element includes the vertical posts, truss 

members, handhole covers, and caps for the column supports 

on the structure. Flange and gusset plates at the column to 

span arm/chord connection are also included with this element. 

The element components may be painted/unpainted/galvanized 

steel or aluminum. This element includes posts for cantilever 

structures such as high mast lights.

S.05 Tower to Truss Chord/Arm Connection(s) - This element 

defines the flange and gusset plates connecting the span arms 

or chords to the column supports. The element components 

may be painted/unpainted/galvanized steel or aluminum. 

63 
Element Number Description 

S.06 Truss Chords/Arms - This element defines the truss frame 

members. The element components may be 

painted/unpainted/galvanized steel or aluminum. Weld cracks 

or connection defects on truss members are to be recognized 

as critical. 

S.07 Truss Struts – This element defines the secondary truss 

members: the diagonal, horizontal, or vertical struts, the 

diagonals and the cross bracing. The element components 

may be painted/unpainted/galvanized steel or aluminum. Weld 

cracks or connection defects on truss members are to be 

recognized using the appropriate element. 

S.08 Cracks - This element addresses cracks in members or welds 

on any structure element, particularly vertical, horizontal and 

diagonal truss members. In general, the less redundant an 

item is, the more critical a deficiency in that item becomes. 

S.09 Chord Splice Connections - This element defines the splice(s). 

The element components may be painted/unpainted/galvanized 

steel or aluminum. This element should also be used for pole 

slip joint connections. 

S.10 Sign Frame and L Brackets - This element defines the Lbrackets, vertical h orizontal braces, and other angers, h

structural members that mount the sign panels to the sign 

arms, chords, or bridge girders (bridge-mounted signs only). 

Unit quantities should reflect each individual L-bracket or 

hanger. Item also includes sign clips (if used). 

S.11 Sign Panels - This element defines the sign panel of the sign 

structure. This rating shall include the legibility of the sign, as 

well as the condition of the structural elements. 

S.12 Catwalk - This element defines the walkway gratings, handrails, 

safety chains, and connections on the sign structure. The 

element may be painted, unpainted, or galvanized steel or 

aluminum. 

S.13 Power and Luminaires - This element defines the visual 

condition of any luminaires in the lighting system on the sign 

structure, as well as the visual condition of any electrical lines 

and boxes. 

S.14 VMS Sign - This element identifies a Variable Message Sign 

(VMS) mounted on the structure. 

S.15 Sign Attachments - This element defines each accessory on 

the sign structure including dampeners, signs mounted on the

tower, traffic-control devices and cameras. 

S.16 Vertical Clearance, Camber and Alignment - This element 

defines the vertical clearances involving the structure, as well 

as the overall status of the alignment of the structure. 

S.17 Protection, - This element defines the state of the devices such 

as guardrails protecting the structure. Evaluate for a distance 

of no more than 300’ from the structure. 

64 
Element Number Description 

S.18 Other, - List any elements that do not fall into any category 

listed above. List each item and state condition. 

Element Condition Rating 

Condition Description Feasible Action 

0 Not Applicable None 

1 Element performs intended function with high None 

degree of reliability (Good) 

2 Element performs intended function with Repair element, 

small reduction in reliability (Fair) increase inspection 

frequency, do nothing 

3 Element performs intended function with Repair or replacement 

significant reduction in reliability (Poor) of element within 

specified time frame

4 Element does not perform intended function Immediate repair or 

with any degree of reliability (Critical) replacement of 

element 

Element S.08 ‘Cracks’ is an interesting rating since it is not specific to an element, rather a 

condition. This element rating, proposed by the New Jersey Department of Transportation, 

allows a condition rating to be applied to a crack such as one would find in an aluminum sign 

truss. It allows the inspector to better define if the crack presents a future danger, such as the 

structure reaching its fatigue life, or just a maintenance or flaw in initial construction. 

Note also that Elements S.11, S.13, S.14, S.16, and S.17 provide various nonstructural 

information on the ancillary structure. 

For each of the eighteen elements, example ratings are provided in Appendix A ‘Example 

Element Ratings’. 

14.0 ELEMENT CONDITION RATING 

An element rating system should be developed to properly assess the current performance 

against the originally intended function. There are many numerical rating systems used around 

the country for structural elements. Since these ancillary structures are usually not as 

complicated as most bridge structures, it is recommended that a simple ‘0’ to ‘4’ rating system 

be used as defined in Table 10. 

Table 10 

An example inspection form developed by South Carolina and based on an element level 

system is contained in Appendix B. In this case a rating scale of 1 to 5 was used, but is 

otherwise similar to that in Table 10. 

65 
14.1 PONTIS Element Definitions and Ratings 

To better correlate with bridge ratings that follow the PONTIS system, this section provides 

guidance for its application to ancillary structures. A sample report is provided in Appendix B. 

This approach defines commonly recognized structural elements (CoRe elements) used for sign 

and high mast light inspections. The following CoRe elements are recommended for use with 

ancillary structures: 

• Foundation(s) 

• Anchor bolt(s) 

• Base plate(s) 

• Column support(s) 

• Column to arm/chord connection 

• Arm/chord member 

• Chord splice connection 

• Span truss members 

• Sign frame 

• Sign panels 

• Catwalk 

• Luminaire 

• Sign attachment 

• Slip joint 

Each CoRe element of an inspected structure can be evaluated and rated based on the rating 

guidelines presented in this section. Each CoRe element was assigned a standard unit type to 

quantify it. For example, the catwalk element is defined in terms of linear feet. If the entire 

catwalk measured 20 linear feet and minor deficiencies were observed on 5 feet of the element, 

15 feet would be allocated as condition state 1, and 5 feet would have be allocated as condition 

state 2. The rating guidelines that follow provide element descriptions, units of measure, 

condition state descriptions, and feasible corrective actions for each CoRe element. Each 

CoRe element listing also considers the material composition and any protective coatings 

present. A Smart Flag should be used to identify member or connection cracks. The 

designation “DN” as a feasible action stands for do nothing.

Foundation(s) S.01 

Units: EA

This element includes foundation(s) that are constructed of reinforced concrete or steel. 

Inspectors should assign ratings based on the overall condition of the foundation and its ability 

to function properly. The condition of grout pads, if present, shall also be included in this 

element. 

Condition state descriptions

1 Good: The element shows no deterioration. There may be discoloration, efflorescence, 

and/or superficial cracking in the concrete but without affect on strength and/or 

serviceability. There is no evidence of active corrosion of the steel. On metal foundations, 

the surface coatings are sound and functioning as intended. 

 Feasible Actions: DN - -

66 
2 Satisfactory: Minor cracks and spalls may be present in the concrete foundation but there is 

no exposed reinforcing or surface evidence of rebar corrosion. Surface rust, surface pitting, 

has formed or is forming on steel foundation. Protective coatings may have minor areas of 

deterioration. 

 Feasible Actions: DN Seal cracks, minor patch -

 Clean and resurface steel 

3 Fair: Some delaminations and/or spalls may be present in the concrete foundation and 

some reinforcing may be exposed. Corrosion of rebar may be present but loss of section is 

incidental and does not significantly affect the strength and/or serviceability of either the 

element or the sign structure. Protective coatings have failed. Surface pitting may be 

present but any section loss due to active corrosion is measurable and does not warrant 

structural analysis. Weep holes in grout pads are clogged or not present. 

 Feasible Actions: DN Clean rebar, patch - 

 and/or seal)

 Clean and resurface steel -

4 Poor: Advanced deterioration. Corrosion of reinforcement and/or loss of concrete section or 

sufficient section loss of the steel is sufficient to warrant analysis to ascertain the impact on 

the strength and/or serviceability of the element and/or the sign structure. 

 Feasible Actions: DN Rehab unit Replace Unit

5 Unknown: The foundation is buried and/or inaccessible and could not be evaluated. 

 Feasible Actions: DN Remove soil and 

 Inspect

Anchor Bolts S.02 

Units: EA

This element defines anchor bolts, anchor nuts, leveling nuts, and washers connecting the 

column support members to the foundation. 

Condition state descriptions 

1 Good: There is no deterioration or misalignment. The elements are fully engaged, tight, and 

in new or like-new condition. 

 Feasible Actions: DN - -

2 Satisfactory: Minor corrosion of the elements may be present. The elements are fully 

engaged. 

 Feasible Actions: DN Tighten/Replace loose -

 hardware 

3 Fair: Moderate corrosion of the elements may be present. Anchor nuts are not fully 

engaged or bolts are misaligned. Washers are missing (if specified on design plans). One 

or two loose nuts may be observed, but do not significantly affect the strength and/or 

serviceability of either the element or the sign structure. 

Feasible Actions: DN Tighten/Replace loose Replace Element 

 Hardware 

67 
4 Poor: Heavy corrosion of the elements may be present. Bolts may be cracked/sheared or 

multiple anchor nuts are loose/missing. There is sufficient concern to warrant an analysis to 

ascertain the impact on the strength and/or serviceability of the element and/or the sign 

structure. 

 Feasible Actions: DN Repair Element Replace Element

5 Not Inspected: The anchor bolts are buried and/or inaccessible. 

 Feasible Actions: DN Remove soil and inspect

 element

Base Plate(s) S.03 

Units: EA

This element defines the base plates, flanges, gusset plates and welds at the connection of the 

column support(s) to the foundation(s). The elements may be painted, unpainted, or 

galvanized. 

Condition state descriptions

1 Good: No evidence of active corrosion. Surface coating is sound and functioning as 

intended to protect the metal surface. 

 Feasible Actions: DN - -

2 Satisfactory: Minor surface corrosion present. 

 Feasible Actions: DN Clean and resurface -

3 Fair: Any protective coating present has failed. Surface pitting may be present but any 

section loss due to active corrosion is measurable and does not warrant structural analysis. 

 Feasible Actions: DN Clean and resurface -

4 Poor: Cracks may be present on the base plate to column support connection weld. 

Corrosion is advanced. Section loss is sufficient to warrant structural analysis to ascertain 

the impact on the ultimate strength and/or serviceability of the element and/or the sign 

structure. 

Feasible Actions: DN Repair element Replace Element

5 Not Inspected: Element is buried and/or inaccessible. 

 Feasible Actions: DN Remove soil and inspect - 

Column Support(s) S.04

Units: EA

This element includes the vertical posts, truss members, handhole covers, and caps for the 

column supports on the structure. Flange and gusset plates at the column to span arm/chord 

connection are also included with this element. The element components may be 

painted/unpainted/galvanized steel or aluminum. 

68 
Condition state descriptions

1 Good: No evidence of deterioration or misalignment. Elements are in new or like-new 

condition. 

 Feasible Actions: DN - -

2 Satisfactory: Minor damage or corrosion is present with no section loss. Handhole covers or 

post caps are missing. 

 Feasible Actions: DN Repair/Replace Elements -

3 Fair: Moderate damage or corrosion is present. Standing water may be observed on the 

inside of the post. Column supports may be out of plumb. 

 Feasible Actions: DN Repair/Replace Elements - 

4 Poor: Heavy damage or corrosion of elements with localized section loss. Elements may be 

misaligned or have severe impact damage that may warrant structural analysis to ascertain 

the impact on the ultimate strength and/or serviceability of the element and/or the sign 

structure. 

 Feasible Actions: DN Rehab unit Replace Unit

5 Critical: Deterioration is so severe that structural integrity is in doubt. Failure may be 

imminent. 

 Feasible Actions: DN Remove from service Replace Unit

Column to Arm/Chord Connection S.05

Units: EA

This element defines the flange and gusset plates connecting the span arms or chords to the 

column supports. The element components may be painted/unpainted/galvanized steel or 

aluminum. 

Condition state descriptions

1 Good: Elements are in new or like-new condition with no significant deficiencies. 

Feasible Actions: DN - -

2 Satisfactory: Minor corrosion with no section loss, minor misalignments, or superficial 

damage to components may be observed. 

 Feasible Actions: DN Clean and resurface -

3 Fair: Significant misalignment of components. Moderate corrosion or damage is present to 

one or more components. 

 Feasible Actions: DN Clean and resurface -

 Repair unit

4 Poor: Major or multiple element defects or section loss that may significantly impact the 

serviceability or integrity of the structure. 

 Feasible Actions: DN Rehab unit Replace Unit

69 
5 Critical: Multiple elements warrant ultimate strength and/or serviceability analysis. 

Feasible Actions: DN Remove from service Replace Unit

Arm/Chord Member S.06

Units: EA

This element defines the truss frame members. The element components may be 

painted/unpainted/galvanized steel or aluminum. Weld cracks or connection defects on truss 

members are to be recognized using the appropriate smart flag. 

Condition state descriptions

1 Good: Elements are in new or like-new condition with no significant deficiencies. 

Feasible Actions: DN - -

2 Satisfactory: Minor corrosion with no section loss, minor misalignments, or superficial 

damage to components may be observed. 

Feasible Actions: DN Clean and resurface -

3 Fair: Significant misalignment of components. Moderate corrosion or damage is present to 

one or more components. 

Feasible Actions: DN Clean and resurface -

 Repair unit

4 Poor: Cracks propagating into any truss member. Major or multiple element defects or 

section loss that may significantly impact the serviceability or integrity of the structure. 

Feasible Actions: DN Rehab unit Replace Unit

5 Critical: Multiple elements warrant ultimate strength and/or serviceability analysis. 

 Feasible Actions DN Remove from service Replace Unit 

Chord Splice Connection S.07

Units: EA

This element defines the splice(s). The element components may be 

painted/unpainted/galvanized steel or aluminum. 

Condition state descriptions

1 Good: Elements are in new or like-new condition with no significant deficiencies. 

 Feasible Actions: DN - -

2 Satisfactory: Minor corrosion with no section loss, minor misalignments, or superficial 

damage to components may be observed. 

Feasible Actions: DN Clean and resurface -

3 Fair: Significant misalignment of components. Moderate corrosion or damage is present to 

one or more components. 

 Feasible Actions: DN Clean and resurface -

 Repair unit

70 
4 Poor: Major or multiple element defects or section loss that may significantly impact the 

serviceability or integrity of the structure. 

Feasible Actions: DN Rehab unit Replace Unit

5 Critical: Multiple elements warrant ultimate strength and/or serviceability analysis. 

Feasible Actions: DN Remove from service Replace Unit

Span Truss Members S.08

Units: LF (Span Length)

This element defines the chord(s). The element components may be 

painted/unpainted/galvanized steel or aluminum. (Ratings in a section of the element are 

rounded to the nearest linear foot of the element.) Weld cracks or connection defects on truss 

members are to be recognized using the appropriate smart flag. 

Condition state descriptions

1 Good: Elements are in new or like-new condition with no significant deficiencies. 

 Feasible Actions: DN - -

2 Satisfactory: Minor corrosion with no section loss, minor misalignments, or superficial 

damage to components may be observed. 

 Feasible Actions: DN Clean and resurface -

3 Fair: Significant misalignment of components. Moderate corrosion or damage is present to 

one or more components. 

Feasible Actions: DN Clean and resurface -

 Repair unit

4 Poor: Cracks propagating into any chord. Major or multiple element defects or section loss 

that may significantly impact the serviceability or integrity of the structure. 

Feasible Actions: DN Rehab unit Replace Unit

5 Critical: Multiple elements warrant ultimate strength and/or serviceability analysis. 

 Feasible Actions: DN Remove from service Replace Unit 

Sign Frame S.09

Units: EA

This element defines the L-brackets, vertical hangers, horizontal braces, and other structural 

members that mount the sign panels to the sign arms, chords, or bridge girders (bridgemounted signs only). Unit quantities should reflect each individual L-bracket or hanger. 

Condition state descriptions

1 Good: The elements are in new or like-new condition with no misalignment. 

 Feasible Actions: DN - -

2 Satisfactory: No serious deficiencies. An occasional loose connection nut may be observed. 

 Feasible Actions: DN Rehab Unit -

71 
3 Fair: Significant deterioration or impact damage may be present. Multiple connection 

components may not be fully engaged. Multiple loose/missing backing strip nuts may be 

observed that could significantly affect the strength and/or serviceability of either the 

element or the sign structure. Connection hardware may need replacement. 

 Feasible Actions: DN Rehab Unit -

4 Poor: Connection components may be cracked, sheared, or missing nuts. Cracks may be 

observed on the welds. There is sufficient concern to warrant an analysis to ascertain the 

impact on the strength and/or serviceability of the element and/or the sign structure. 

Feasible Actions: DN Replace Unit - 

5 Critical: Any collision damage or deterioration significant enough to threaten collapse or 

separation from the sign structure. 

 Feasible Actions: DN Remove from service Replace Unit 

Sign Panels S.10 

Units: SF

This element defines the sign panel of the sign structure. This rating shall include the legibility 

of the sign, as well as the condition of the structural elements. 

Condition state descriptions

1 Good: The elements are in new or like-new condition with no misalignment. 

 Feasible Actions: DN - -

2 Satisfactory: Minor loss of element legibility due to dulled paint or reflectorization. A few 

loose or missing backing strip nuts may be observed on back of the panels. 

 Feasible Actions: DN Rehab Unit -

3 Fair: Graffiti, vandalism, or collision damage may be present but not affecting element 

legibility. Moderate deterioration or impact damage to panels or connecting components. 

 Feasible Actions: DN Rehab Unit Replace Unit

4 Poor: Signs are difficult to read for any reason. Significant deterioration or damage to the 

sign panel and/or connecting components. 

 Feasible Actions: DN Replace Unit - 

5 Critical: Any collision damage or deterioration significant enough to threaten collapse or 

separation from the sign structure. 

 Feasible Actions: DN Remove from service Replace Unit

Catwalk S.11

Units: LF

This element defines the walkway gratings, handrails, safety chains, and connections on the 

sign structure. The element may be painted, unpainted, or galvanized steel or aluminum. 

72 
Condition state descriptions

1 Good: The connections are in new or like-new condition with no significant deficiencies or 

evidence of active corrosion. 

 Feasible Actions: DN - -

2 Satisfactory: Minor damage or deterioration of the element may be observed. Connections 

may have loose nuts but have no significant deficiencies. 

 Feasible Actions: DN Rehab unit -

3 Fair: Moderate deterioration of the connections may be present. Handrails and locking pins 

may be misaligned or inoperable. Safety chain(s) may be missing or deteriorated. 

 Feasible Actions: DN Rehab unit -

4 Poor: Sections of gratings or handrails may be misaligned, unstable, damaged or missing. 

Damage is sufficient to warrant structural analysis to ascertain the impact on the ultimate 

strength and/or serviceability of the element. Heavy deterioration of the connections may be 

present. 

 Feasible Actions: DN Rehab unit Replace Unit

5 Critical: Any collision damage or deterioration significant enough to threaten collapse or 

separation from the sign structure. 

Feasible Actions: DN Rehab unit Replace Unit

Luminaire S.12 

Units: EA 

This element defines each luminaire in the lighting system on the sign structure. 

Condition state descriptions

1 Good: Elements is fully functional and in new or like-new condition with no significant 

deficiencies. 

Feasible Actions: DN - -

2 Satisfactory: Minor damage of the element may be observed. Element may be misaligned. 

 Feasible Actions: DN Rehab unit -

3 Fair: Light cover latches are broken or rusted shut. Missing cover plates. Loose, broken or 

missing sections of conduit. Open electrical boxes. 

 Feasible Actions: DN Rehab unit -

4 Poor: Broken or missing covers. Burned out bulbs/ballasts or missing light fixtures. 

Exposed wiring or unattached electrical boxes. 

Feasible Actions: DN Rehab unit Replace Unit

5 Critical: Any collision damage or deterioration significant enough to threaten separation from 

the sign structure. 

 Feasible Actions: DN Rehab unit Replace Unit

73 
Sign Attachment S.13

Units: EA 

This element defines each accessory on the sign structure including dampeners, signs mounted 

on the column supports, traffic-control devices and cameras. 

Condition state descriptions

1 Good: Element is fully functional and in new or like-new condition with no significant 

deficiencies. 

 Feasible Actions: DN - -

2 Satisfactory: Minor damage, deterioration, or misalignment of element may be observed. 

Feasible Actions: DN Rehab unit -

3 Fair: Moderate damage or deterioration of element, however the element remains functional. 

Feasible Actions: DN Rehab unit -

4 Poor: Serious damage or deterioration to element is reducing the functional performance of 

the unit. 

 Feasible Actions: DN Rehab unit Replace Unit

5 Critical: Any collision damage or deterioration significant enough to threaten separation from 

the sign structure. Any exposed wiring or other dangerous condition. 

 Feasible Actions: DN Rehab unit Replace Unit

Slip Joint S.14

Units: EA 

This element defines the slip joint connection on high-mast light structures. 

Condition state descriptions

1 Good: Element is in new or like-new condition with no significant deficiencies. 

 Feasible Actions: DN - -

2 Satisfactory: Misalignment or minor corrosion of element may be observed. 

Feasible Actions: DN - -

3 Fair: Minor cracking of element or moderate corrosion. There is not sufficient concern to 

warrant an analysis to ascertain the impact on the strength and/or serviceability of the 

element and/or the sign structure. 

 Feasible Actions: DN Repair unit -

4 Poor: Cracking of element or significant corrosion. There is sufficient concern to warrant an 

analysis to ascertain the impact on the strength and/or serviceability of the element and/or 

the sign structure. 

Feasible Actions: DN Rehab unit Remove from service

74 
5 Critical: Structure is in imminent danger of collapse. Multiple elements warrant ultimate 

strength and/or serviceability analysis. 

Feasible Actions: DN Remove from service -

Weld Crack (Smart Flag) S.15

Units: EA 

This smart flag addresses cracks in welds on any sign structure element, particularly vertical, 

horizontal and diagonal truss members. In general, the less redundant an item is, the more 

critical a deficiency in that item becomes. This smart flag only refers to weld cracks. Other 

cracks should be identified in the rating for the appropriate element effected. 

Condition state descriptions

1 Minor: One or two minor “weld pool” cracks are present. Cracks that are short in length and 

shallow in depth, which may be grinded out for repair. This rating would also encompass 

incomplete welds or other minor fabrication defects in welded connections of truss 

members. 

 Feasible Actions: DN Monitor condition Repair unit

2 Fair: Several weld pool cracks are present, or a hairline crack exists at one or two 

redundant members. There is not sufficient concern to warrant an analysis to ascertain the 

impact on the strength and/or serviceability of the element and/or the sign structure. 

 Feasible Actions: DN Monitor condition Repair unit

3 Poor: Several hairline cracks are present, a single crack has visible width, or the welded 

connection has been severed on a redundant truss member. Any condition where there is 

sufficient concern to warrant an analysis to ascertain the impact on the strength and/or 

serviceability of the element and/or the sign structure. 

 Feasible Actions: DN Repair/rehab unit Remove from service

4 Critical: Crack has propagated into a non-redundant structural member (i.e. column or 

chord), or the welded connection has been completely severed. Multiple cracks on structure 

have created a condition such that the structure is in imminent danger of collapse. 

 Feasible Actions: DN Remove from service -

15.0 INSPECTION REPORT 

Reporting of deficiencies, condition ratings, and notification of any critical conditions can occur 

in a number of ways. Many agencies have opted for an electronic process, either using hand 

held devices or laptop computers to record information out in the field. It is important, whether 

using a paper reporting procedure or an electronic system, that all aspects of the report be 

finalized before leaving the site. 

The inspection report should summarize many aspects of the inventory and inspection process 

but first and foremost identify deficiencies that may require maintenance or result in structural 

failure. The report is used as a tool to manage the ancillary structure inventory and must be 

complete, concise, and accurate. It should clearly call out any recommendations for further 

action. A recommended list of items to be included in a typical inspection report are listed 

below: 

75 
♦ Inventory Information 

♦ Personnel / Firm / Inspector information 

♦ Inspector Ratings 

♦ Inspector Repair Recommendations (May include prioritization. See Section 16.1) 

♦ Inspector Recommendation on Inspection Frequency 

♦ General Photos 

♦ Deficiency Photos 

♦ Sketches 

♦ NDT Results (if applicable) 

Inspection reports may take any number of forms. Most reports are submitted as electronic 

files, either as individual reports or part of a database management system. For documentation 

purposes, a paper copy, signed by the responsible party, is also normally required. 

An example inspection report for a New Jersey Sign Structure utilizing an element based 

inspection system is located in Appendix C. An example inspection report in the PONTIS 

system is located in Appendix B. 

Condition Description Repair Timeframe 

0 Not Applicable None 

1 Items, if not corrected immediately, threaten 3 days 

the continued operation of the structure 

2 Items that need to be corrected in a timely One Year 

manner, above normal maintenance repairs. 

3 Items that can be corrected during normal Three Years 

maintenance operations. 

Repair Priority Rating 

16.0 MAINTENANCE AND REPAIR 

16.1 Prioritization of Work 

A protocol should be developed whereby deficiencies identified during the inspection can be 

addressed in a timely manner. The repair priority rating system given in Table 11 is one 

example. If Priority 1 repairs cannot be made within a reasonable timeframe, removal of the 

sign structure may be warranted. 

Table 11 

For emergency situations, a Condition ‘E’ can be applied whereby the roadway may have to be 

immediately shut down. The inspection team should have a direct contact person to notify if any 

critical conditions are found. There have been cases where the inspection team and their traffic 

control remained on site while maintenance personnel and equipment mobilized to the site and 

removed structures found in critical condition. Many states have such procedures for bridge 

inspectors, and a similar protocol can be followed for ancillary structures. 

76 
Overhead sign structures can vary in cost from $10,000 to $150,000 depending on complexity. 

In comparison to other highway structures such as bridges, this is a relatively minor cost. For 

this reason many states that have found structurally deficient sign structures, decide on total 

removal and replacement rather than repair. If repairs are made it may be only a temporary 

measure. Some deficiencies like cracked welds, even if found on only one or two elements, are 

indicators that the structure has most likely reached its fatigue life and replacement is 

warranted. 

Of course each sign structure should be evaluated on cost/benefit value when considering 

repair or replacement. Other factors such as traffic control could greatly add to the cost of total 

replacement. 

16.2 Routine Maintenance 

Ancillary structures, especially sign bridges, typically require lane closures and disruption of 

traffic flow, in order to access the structure for repairs and thus the inspector may be asked to 

perform routine maintenance at the time of the inspection. If not performed by the inspection 

team, this work should be completed by maintenance crews in a timely manner. Examples of 

deficiencies that require typical routine maintenance are: 

♦ Loose nuts 

♦ Loose or missing sign fasteners 

♦ Broken washers 

♦ Buried foundations 

♦ Clogged post drainage 

♦ Excessive vegetation 

♦ Rodent droppings 

♦ Spot loss of galvanization 

♦ Replacing pole caps, hand hole covers, anchor rod caps 

16.2.1 Foundations 

Routine Maintenance for foundations includes making sure that the foundation is visible to the 

inspector. If buried, this can accelerate corrosion and will not yield a full inspection. Many times 

not only are the foundations buried but the base plates and anchor rods are as well. This can 

be attributed to the widening of many highway shoulders where ancillary structures are 

positioned. 

Drainage issues are very important for sign structures. Many structures are inspected and 

found to have standing water in the post. Drilling a small hole in the post to allow drainage or 

creating drain grooves in the top of the foundation can easily be done during routine 

maintenance. Blocked drain grooves are the most problematic maintenance item that can lead 

to catastrophic results. Inspectors and/or maintenance personnel should routinely clean the 

outlet simply using a screwdriver head or other probing tool. 

Buried foundations should be uncovered and area around them regraded. Any buried 

foundations should be exposed to at least .3m (1 ft.) below the top of the foundation. Any 

excessive vegetation should be removed since it not only impedes inspections but harbors 

moisture and rodents. 

77 
Missing handhole covers can be a safety concern especially if electrical power is inside the 

post. Also, moisture, animals, birds and garbage can enter the handhole. It is recommended 

that all missing handhole covers be replaced. Missing post or truss end caps have the same 

potential problems and should be replaced. In addition to handholes sometimes there are 

conduit access holes, usually small holes 25mm to 50mm (1 inch to 2 inches) in diameter that 

allow small birds and insects to enter. An easy repair is to plug the hole with a plastic conduit 

end cap. A small hole may be drilled through the cap to allow airflow. 

16.2.2 Connections 

Missing or loose anchor rod nuts, both top nuts and leveling nuts, can be a serious problem 

since the load is then transferred to the adjacent rods. In many older cantilever structures there 

are only a total of four rods, so just one missing or loose nut can overload the remaining three 

rods. Damaged nuts should be replaced and loose nuts properly tightened. 

Missing, broken, or loose bolts in member connections should be replaced. Consideration 

should be given to replacing aluminum bolts or black bolts used in structural connections with 

galvanized high strength bolts. 

Many sign structures were constructed with steel towers/posts and an aluminum truss. The 

lighter aluminum helped to reduce structural loading. However, with these dissimilar metals it is 

important that the nonconductive materials, such as polymer pads, placed as barriers between 

the dissimilar materials remain so these materials do not touch and accelerate corrosion. 

Missing pads should be replaced in a timely manner. 

The numerous fasteners that connect sign panels to the structure can loosen and fall off. 

Missing fasteners should be replaced unless it is determined that sufficient redundancy exists in 

the connection. A simple rule of thumb might be, fastener replacement is necessary if more 

than 20 percent of the connections are missing. 

16.2.3 Coatings 

Many steel structures have been galvanized to slow the corrosion process. Over time the 

galvanized layer may become ineffective and therefore lose its ability to slow the process of 

corrosion. Impact damage can also remove the protective coating. If there is minor loss of 

galvanization a touch up may be prudent. Total loss of galvanization may not be an immediate 

problem is there is no visible corrosion or section loss, but may result in a shorter structure 

service life. 

Suggestions for routine maintenance of coatings include the following: 

♦ Clean debris from structure, remove or cut vegetation touching structure. 

- This is particularly important for weathering steel 

- Remove bird droppings that can accelerate corrosion 

78 
♦ Touch up of galvanizing 

- Repair in accordance with ASTM A780 “Standard Practice for Repair of 

Damaged and Uncoated Areas of Hot-Dip Galvanized Coatings” 

- The surface should be ground to bright metal 

- A zinc rich paint or cold galvanizing compound should be applied 

♦ Painted structures 

- Paint must be removed to inspect suspected cracks 

- Repaint immediately after inspection (if OK) or after repair 

- Touch-up paint any scratches or locally defective areas 

16.3 Repairs 

In recent years many innovative repair methods have been researched and implemented for 

overhead sign structures. The most progress has been made regarding aluminum truss 

structures. These welded structures are very difficult to field repair. Even truss removal and 

repair is considered much more difficult than with a steel truss. The following paragraphs 

provide repair guidance for typical problems. 

16.3.1 Foundations 

16.3.1.1 Concrete 

The foundations of ancillary structures are susceptible to deterioration due to their proximity to 

the traveled roadway and the influence of surrounding site conditions. Concrete, the most 

prevalent material type of foundation used, will deteriorate by cracking, delaminating and 

spalling. These types of deficiencies can be repaired so that the service life of the structure can 

be maintained. 

Deterioration that includes cracking, spalling and delamination can be repaired as would be 

done with other concrete structures. The deteriorated or damaged concrete can be chipped 

away and replaced with mortar. Cracks can be sealed with epoxy or epoxy grout depending on 

their size. Large spall areas can be repaired with reinforcing that is drilled and bonded into the 

existing foundation for an integral connection. 

A common deficiency that typically requires repair for an ancillary structure is the grout pad 

between the top of foundation and base plate. This mortar type mix is not the reinforced 

concrete used in other parts of the foundation, and usually serves only to support the steel base 

plate in compression. One easy repair is to completely remove the grout pad, if analysis can 

show that the base plate will meet existing buckling specifications without the pad. Once the 

grout pad is removed the gap area between the foundation and base plate should be closed off 

with wire mesh to prevent intrusion of debris or rodents into the post base. 

If the grout pad is determined by analysis to be required to prevent the base plate from buckling, 

the grout should be completely removed and replaced using a prepackaged “non-shrink” grout 

placed in accordance with the manufacturer’s requirements. The grout pad design should 

accommodate any drainage from the post and provide for adequate air circulation. 

79 
16.3.1.2 Anchor Rods 

This critical connection between the post and foundation has been problematic. Many times the 

rod is not long enough and the anchor nut is not fully engaged. This in itself is not a serious 

deficiency as long as at least three quarters of the nut is engaged. If not, a coupler may have to 

be installed to lengthen the rod. This may involve complete foundation reconstruction. The first 

course of action is to see if the base plate can be lowered to fully engage the nuts. 

A rod that is found to be fractured or does not meet required embedment lengths presents a 

serious condition. One method of adding anchor rods is to drill through the base plate and into 

the foundation so that new rods can be epoxy grouted into place, see Figure 35. Installation 

may be hindered by closely spaced base plate stiffener plates and may cut reinforcing steel in 

the foundation. 

Figure 35. Base plate with Added Anchor Rods. 

In many states a new foundation is built adjacent to the old and the structure is relocated to the 

new foundation. For multi-tower sign structures or those with eight or more anchor rods with 

high redundancy a fractured anchor rod may not be critical. An analysis should be conducted to 

investigate the effects prior to determining repairs. 

When replacing a nut or washer, wire brush and lubricate the anchor rods, use new top nuts 

and washers, lubricate the nuts, and tighten. Beeswax or toilet ring wax are good lubricants. 

16.3.2 End Frames and Posts 

End frames and posts connect ancillary structures to their foundations and are susceptible to 

damage from vehicles and maintenance operations. Common deficiencies covered here for 

repair include gouges, corrosion, impact damage and weld cracking. 

80 
16.3.2.1 Gouges 

Gouges are common deficiencies in the end frame posts of ancillary structures since they can 

come in contact with machinery, vehicles and pedestrians. The size of the gouge in relationship 

to the size of the element will help determine the repair strategy. Gouges greater than 3 mm 

(1/8 inch) deep but less than half the member thickness may be ground with a transition slope to 

reduce the possibility of cracking. This repaired member will be more susceptible to fatigue and 

therefore should be inspected more frequently. Gouges greater than half of the member 

thickness can also be ground but the reduced structural capacity of the effected area should be 

investigated. 

16.3.2.2 Impact Damage 

Damage to end frames and posts due to impact are common. If gouges occur due to impact the 

proceeding paragraph provides repair guidance. Dents from impact need to be evaluated for 

reduced structural capacity due to local buckling. All welds in effected members need to be 

inspected for potential cracking from the impact force. Weld repairs should be made in 

conformance with the AWS Bridge Welding Code. 

16.3.2.3 Corrosion 

Where bases of end frames or posts exhibit corrosion, the source of moisture should be 

removed whenever possible by regrading and removing vegetation. Corroded areas should be 

properly cleaned and recoated. If corrosion has caused enough section loss to reduce the 

structural capacity of the member below required values, the area can be strengthened with 

steel collars or concrete encasement. 

16.3.3 Trusses and Mast Arms 

Many sign structure trusses are three dimensional space frames. In determining the need and 

type of repairs to these structures, consideration should be given to the significant redundancy 

many of them possess. In an unpublished load test of a four-chord bridge structure by the Iowa 

Highway Department, the structure was able to carry in excess of its design load even when 

numerous members were totally cut. 

16.3.3.1 Connections 

Sign structures arrive in sections for transportation and are erected at the site. Many times the 

connections do not always perfectly fit together. This may not be a serious problem if the gap 

created by the misalignment covers less than 25 percent of the total faying surface area. If the 

gap is greater, shims should be used to provide even contact. Shims should not be inserted 

into a tightened connection; rather, the connection must be loosened, shims inserted, and then 

retightened. 

16.3.3.2 Cracks 

Weld crack problems with steel structures are easier to repair than aluminum. The repair may 

be made ‘in-situ’ or that portion of the structure can be removed from service and repaired. 

Corrections to weld problems may include hammer peening, hole drilling to arrest the crack, 

vee-and-welding, or detail modification. 

81 
Hammer peening provides a compressive stress to the weld surface that helps to reduce the 

tendency to crack and to keep any crack from propagating. It has been useful for fatigue 

cracks up to 3 mm (1/8 inch) deep. Hammer peening followed by surface grinding can increase 

the strength of the connection by one fatigue strength category. Ultrasonic Impact Treatment 

(UIT), sometimes called ultrasonic peening, is a recently developed technique used to treat fillet 

welds to increase their fatigue strength. This has been used in Texas to treat welds in ancillary 

structures and is a patented process developed by Applied Ultrasonics. 

A drilled hole is often used to arrest a crack that goes through the entire thickness of the weld 

material. For small cracks this may be enough to arrest the crack permanently, but offers only 

a temporary fix for larger cracks. The diameter of the hole to be drilled is often taken as 20mm 

(.75 inch); however, a more structure specific hole size can be calculated based on the stress 

range, edge distance and yield strength of the material. The inside of the drilled hole should be 

tested with dye penetrant to assure that the crack end was removed. Figure 36 illustrates actual 

crack repair details. 

Figure 36. Repair Detail for Overhead Sign Truss Chord Crack. 

16.3.4 Longitudinal Splits or Cracks 

Longitudinal splits and cracks generally develop due to freezing of trapped water or build up of 

packout corrosion in slip joints. Longitudinal cracking at slip joints can also occur due to 

excessive bending stresses. 

Slip joints, or telescoping splices that may develop packout corrosion, particularly a problem 

with weathering steel, should be sealed around their base with a weld, epoxy, or silicone sealant 

If a longitudinal split or crack in a telescoping splice extends beyond the telescoping splice, the 

pole should be replaced. 

If the longitudinal split or crack does not extend beyond the telescoping splice, the pole may be 

repaired by applying stressed steel bands around the perimeter. A 25 mm (1 inch) diameter 

hole should be drilled at the end of the split or crack, followed by applying steel bands around 

the post at the crack. The bands must be designed to replace the strength of the section area 

82 
of the cracked length of the member. Poles prone to this splitting can be retrofitted with the 

bands as a preventive measure. Members with small splits (less than two times the diameter) 

due to freezing water inside them can also be repaired in this way. Where freezing has 

occurred, 25 mm (1 inch) holes should be drilled near the bottom of the member and similar 

members to drain any water. Members with larger splits should be considered for replacement. 

16.3.5 Composites for Repairs 

Research conducted at the University of Utah for the Utah State DOT and New York State DOT 

has resulted in a fiber composite wrap that surrounds the deficient weld area and helps transfer 

the load past the area of damage. It is an attractive repair option since it can be installed in-situ 

with materials that cost just a few hundred dollars. 

16.3.5.1 Material Properties 

The fiber composite wrap is actually a Fiber Reinforced Polymer (FRP). An approved installer 

that is thoroughly trained by the specific manufacturer should install the material. Surface 

preparation is critical and installation should only occur during weather deemed acceptable by 

the manufacturer. Surface preparation can include scrubbing, acid etching, water rinse and airdrying. The cure time for the applied repair resins is usually about one hour. 

16.3.5.2 Repair Examples 

A good example of such an application is repair to an aluminum sign truss bridge. During 

inspection it was found that the welds connecting the diagonals to the chord had cracked over a 

significant portion of their length. FRP was chosen as a repair technique. The application 

included member cleaning and application of the FRP material using strips wrapped around the 

members. Figure 37 below shows the completed application. These repairs, initially thought to 

be just temporary for one year or less, are now being considered as a permanent repair 

solution. 

Figure 37. Repair of Truss Members Using FRP. 

83 
16.3.6 Vibration Dampeners 

Many ancillary structures, especially mast arm type, can visibly be seen vibrating under load. 

Though structurally sound, the excessive vibration may cause concern to the traveling public. 

The recommended repair is installation of a dampener to reduce the displacements. 

16.3.6.1 Types of Dampeners 

The most common type of dampener found on ancillary structures is the Stockbridge damper, 

also called a dog bone damper, see Figure 38. There are two weights on the end of a flexible 

shaft that can be tuned based on the natural frequency of the structure and thereby offer 

maximum effect. They are also very easy to install on existing structures as a retrofit. 

Figure 38. Stockbridge Damper. 

To counteract galloping of signal arms a flat panel called a sign blank can be installed 

horizontally directly over the signal head acting as a drag against the up and down motion. The 

sign blank must be correctly placed over the signal head to break the airflow. This type of 

dampener has been used in Texas, see Figure 39. Other dampeners developed include the 

Florida impact damper and the Wyoming strand damper.

Figure 39. Texas Flat Panel Damper. 

84 
For natural horizontal wind gusts the Wyoming strand damper, Figure 40, is also helpful as is 

any kind of horizontal strut that can reduce out of plane bending. 

Figure 40. Wyoming Strand Damper. 

85 
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86 
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87 
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Fisher, J.W., Barthelemy, B.M., Mertz, D.R., and Edinger, J.A., NCHRP Report 227: Fatigue 

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National Council, Washington, D.C., 1980. 

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“Proceedings of the 12th International Conference on Offshore Mechanics and Arctic 

Engineering Conference (OMAE), 20-24 June 1993, Salama et al. Eds., ASME, Vol. III, 

Part B, Materials Engineering, pp. 875-882, 1993. 

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Detection and Repair of Fatigue Damage in Welded Highway Bridges, Transportation 

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88 
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89 
APPENDIX A 

EXAMPLE ELEMENT RATINGS

Foundation – S.01 

Figure A1

Buried Foundation 

S.01 rate as ‘0’, Not 

Applicable. 

However, if opposite tower 

foundation is exposed, rate 

S.01 for that foundation, state 

in notes buried foundation and 

recommend as Priority 3 to 

expose. 

Figure A2 

Deteriorated Grout Pad 

S.01 rate as 3, Priority 2 

repair. 

Note also leveling nut 

corrosion (S.02 Item). 

For Element Condition Rating, Ref. Table 10. 

For Element Repair Priority, Ref. Table 11 

A-1 
Anchor Rods – S.02 

Figure A3 

Missing Anchor Nut. 

If Span structure, rate as 2, 

Priority Repair 2. If Cantilever 

structure, rate as 3, Priority 

Repair 1. 

Figure A4 

Anchor rods not fully engaged. 

If 80% threaded, note on report, 

rate S.02 as ‘1’, no repair. 

Loose Nuts (Washers Slip) 

Less than 50% slip, rate S.02 as 

‘2’, Priority Repair 2. 

More than 50% slip, rate S.02 

as ‘2’, Priority Repair 1. 

A-2 
Base Plate(s) – S.03 

Figure A5 

Steel Base Plates 

Rate as ‘1’, Good Condition 

No weld cracks, no cracks in

base plate, and no visible 

warping. 

Figure A6 

Buried Aluminum Base Plate 

Rate as ‘0’, Not Applicable. 

However, if a span and opposite 

tower base plate is exposed, 

rate for that base plate, state in 

notes buried base plate and 

recommend as Priority 3 to 

expose. In any case all buried 

elements should be exposed 

per specification/plans. 

A-3 
Towers – S.04 

Figure A7 

1” to 2” Band of surface 

corrosion at base of post. Dmeter results indicate no overall 

section loss. 

Rate 2, Small reduction of 

reliability. 

However, if overall section loss 

in cantilever > 25%, rate 4, 

repair priority 1. 

Figure A8 

Dent, tear, and weld crack in 

first strut on tower. 

Rate as 2, Repair on Priority 3

basis. 

A-4 
Tower to Truss/Chord/Arm Connection(s) – S.05 

Figure A9 

Gap between upper chord and 

shim pack and inadequate 

shim plate placement. 

Rate 2, Repair priority 3. 

Repair recommendation would 

be to properly place and add 

shim plates as necessary. 

Figure A10 

Gap between lower chord and 

saddle block, loose u-bolt. 

Rate 2, Repair as priority 3. 

Repair recommendation would

be to add shims under saddle 

block to close gap at chord. 

The inspector would tighten 

the u-bolt during inspection. 

A-5 
Truss Chords/Arms – S.06 

Figure A11 

Minor surface corrosion 

observed on dual trussed 

arms. 

Rate 1 

Figure A12 

Minor 4” diameter ding in 

lower chord. Right rear end 

cap missing. 

Rate 2, Repair priority 3 

A-6 
Truss Struts – S.07 

Figure A13 

1.5” and 2.5” tears in strut 

member. 

Rate 3, Repair Priority 1 

Note: This strut has a cracked 

weld at the lower chord. 

Figure A14 

2” +/- diameter defect in 

aluminum strut. 

Rate 1 

Note: The rating of 1 is for a 

structure with no other 

deficient struts. This 

structure’s struts are actually 

rated 3 due to this and other 

deficiencies. 

A-7 
Cracks – S.08 

Figure A15 

Weld crack in member U14 - 

L15 at L15. The weld crack is 

approximately 4" long x 1/8" 

wide and is propagating into the 

diagonal 1/2". 

Rate 4, Repair priority 1 

Figure A16 

1” long weld crack at lower 

chord. 

Rate as 3, Repair priority 1 

A-8 
Chord Splice Connection(s) – S.09 

Figure A17 

Three loose fasteners that could 

not be tightened by the 

inspector. Gap in chord splice. 

Rate 3, Repair priority 2 

Figure A18 

One of several severely 

deteriorated splice bolts. 

Rate 4, Repair priority 1 

A-9 
A-10 

Sign Frame and L-Brackets – S.10 

Figure A19 

Missing one U-bolt at the lower 

chord to vertical sign member. 

Rate 1, Repair priority 3 

Figure A20 

Sign 5 exhibits severe impact 

damage with missing members 

and hardware. 

Arrow shows broken bracket. 

Rate 3, Repair priority 2 
Sign Panels – S.11 

Figure A21 

Sign 5 exhibits severe impact 

damage with approx. 1/2 the 

lower section of the sign panel 

missing, see arrow. 

Rate 3, Repair priority 2 

Figure A22 

Sign panel No. 2 was reused 

from old sign structure and is in 

fair condition. 

Rate 1 

A-11 
Catwalk – S.12 

Figure A23 

Portion of catwalk over main line 

above lanes 1,2 and 3 exhibits 

severe impact damage, and has 

apparently been removed from 

this section. 

Rate 4, Repair priority 3 

Figure A24 

The catwalk nosing exhibits 

moderate impact damage 

between the left most and 

middle light fixtures. 

Rate 2, Repair priority 3 

A-12 
Power and Luminaires – S.13 

Figure A25 

Lighting and framework has been 

removed. A section of 

abandoned conduit at the center 

of the truss is held in place by 

electrical wires on one end and 

one u-clamp at the other. 

Rate 0, Repair priority 2 

Repair priority 2 due to the 

inadequate attachment of the 

abandoned conduit. 

Figure A26 

Lighting for sign #1 is missing due 

to impact damage. Exposed 

wires present. 

Rate 4, Repair priority 2 

A-13 
Sign Attachment(s) – S.15 

Figure A27 

Left rear post "No trucks in left 

lane" sign u-bolts are too large 

and sign is free to rotate. 

Rate 2, Repair priority 3 

Figure A28 

"No Trucks In Left Lane" (4' x 5') 

sign attached to the left rear post 

(facing the westbound traffic) 

exhibits moderate impact 

damage. 

Rate 3, Repair priority 3 

A-14 
Vertical Clearance, Camber and Alignment – S.16 

Figure A29 

Adequate camber, alignment and 

vertical clearance over all lanes 

under span. 

Rate 1 

Figure A30 

Adequate camber, alignment and 

vertical clearance over all lanes 

under the cantilever. 

Rate 1 

A-15 
Protection – S.17 

Figure A31 

Severe impact damage to guide 

rail. Damage to guide rail 

directly effects the protection of 

sign structure and motorist. 

Rate 4, Repair priority 1 

Note: This guide rail has since 

been replaced. 

Figure A32 

Eastbound Loc. Rt Side: Impact 

damage to guide rail 3yds east

of tower. Damage doesn't 

significantly impact protection of 

structure or motorist. 

Rate 2 

A-16 
Other – S.18 

Figure A33

24 feet east of sign structure is

an abandoned service pit with

no cover

Rate 4, Repair priority 2 

The service pit/vault should be 

closed to protect the motorists. 

24 f e et 

Figure A34 

RTMS traffic device attached to 

right rear post. 

Rate 1 

A-17 
APPPENDIX B 

EXAMPLE INSPECTION REPORT FORMS 

B-1 
B-2 
B-3 
B-4 
B-5 
B-6 
B-7 
APPENDIX C 

SAMPLE INSPECTION REPORT

C-1 
C-2 
C-3 
C-4 
C-5 
C-6 
C-7 
C-8 
C-9 
C-10 
C-11 
C-12 
C-13 
C-14 
C-15 
C-16 
C-17 
C-18 
D-1 

APPENDIX D 

ULTRASONIC ANCHOR INSPECTION PROCEDURE
D-2 
D-3 
D-4 
D-5 
D-6