Maintenance of Signs and Sign Supports
A Guide for Local Highway and Street Maintenance Personnel
This document is disseminated under the sponsorship of the Department of Transportation in the interest of information exchange. The United States Government assumes no liability for its content or use thereof.
The contents of this report reflect the views of the author, who is responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official policy of the Department of Transportation.
This report does not constitute a manual, handbook, standard, specification, or regulation.
The United States Government does not endorse products or manufacturers. Any trademarks or manufacturers' names that appear herein do so only because they are considered essential to the objective of this document.
Technical Documentation Page
1. Report No. FHWA
2. Government Accession No.
3. Recipient's Catalog No.
4. Title and Subtitle
Maintenance of Signs and Sign Supports: A Guide for Local Roads Maintenance Personnel
5. Report Date
6. Performing Organization Code
Hugh W. McGee, P.E.
8. Performing Organization Report No.
9. Performing Organization Name and Address
10. Work Unit No.
Vanasse Hangen Brustlin, Inc.
11. Contract or Grant No.
12. Sponsoring Agency Name and Address
Office of Safety
13. Type of Report and Period Covered
14. Sponsoring Agency Code
15. Supplementary Notes:
The FHWA Office of Safety Contract Task Order Manager was Karen Timpone. The Technical Oversight Working Group included: Thomas Ballard, Eugene Calvert, Tim Colling, Mark Hood, William Lozier, Jon Oshel, Joe Marek, and Tom McDonald.
Highway signs are the means by which the road agency communicates the rules, warnings, guidance and other highway information that drivers need to navigate their roads and streets. This guide, which is an update to the same titled guide published in 1990, is intended to help local agency maintenance workers ensure their agency's signs are maintained to meet the needs of the road user. The guide succinctly covers the following topics: a description of sign types, sign materials and sign supports; sign installation and the elements of a sign management system including inventory, inspection, preventive maintenance, repair and replacement, and recordkeeping.
17. Key Words
Signs, sign supports, maintenance, replacement, sign management.
18. Distribution Statement
No restrictions. This document is available to the public through the National Technical Information Service, Springfield, VA 22161.
19. Security Classif. (of this report)
20. Security Classif. (of this page)
21. No. of Pages:
Form DOT F 1700.7 (8-72) - Reproduction of completed pages authorized
This guide was prepared by Vanasse Hangen Brustlin, Inc. (VHB) under FHWA Contract DTFH61-05-D-00024. Ms. Karen Timpone, Federal Highway Administration Office of Safety, was the Task Order Manager. The principal investigator and author was Dr. Hugh McGee, P.E. of VHB. Document preparation was performed by Ms. Michelle Scism of VHB.
A Technical Working Oversight Group was formed to guide the preparation of this document. The members included:
- Thomas G. Ballard, P.E., TBA Consulting, Inc.
- Eugene Calvert, P.E., PTOE, Collier County, FL.
- Tim Colling, P.E., Michigan Local Technical Assistance Program.
- Mark Hood, P.E., Pennoni Associates.
- William Lozier, P.E., Licking County, OH.
- Jon Oshel, P.E., Oregon Counties Association
- Joe Marek, P.E., Clackamas County, OR.
- Tom McDonald, P.E., Iowa Local Technical Assistance Program.
Their input and review were invaluable.
- Traffic signs are critical elements of the highway because they communicate the rules, warnings, guidance, and other highway agency information that drivers need to safely and efficiently navigate roads and streets. Well maintained signs are important as they help drivers make good decisions. This guide is intended to help local agency maintenance workers ensure their signs are maintained to meet this need.
This guide is not a comprehensive design guide for roadway signing—there are many aspects to signing that cannot be covered here. For standards and guidance on all signs, refer to the Manual on Uniform Traffic Control Devices (MUTCD), the Standard Highway Signs Handbook, and the many other references found at the end of this guide. These references provide more detailed information on the sign topics briefly covered here:
- Principles and Types.
- Management System.
- Preventive Maintenance.
- Repair and Replacement.
Appendices are provided for:
A. Materials and equipment used for sign maintenance.
B. Clear zone description.
C. Typical work zone traffic control plans for sign maintenance activities.
Traffic Sign Principles
While there is much to be said about the design, placement, operation, and maintenance of signs (see, for example, The Traffic Signing Handbook), there are a few keyprinciples that are critical for traffic signs to be effective. As with any traffic control device, a traffic sign should meet five basic requirements stipulated in the MUTCD, namely:
- Fulfill a need;
- Command attention;
- Convey a clear, simple meaning;
- Command respect from road users, and
- Give adequate time for proper response.
Even during maintenance operations, it is important for staff to question every sign that they work on to see if it is needed and meets standards applicable to its use. The decision to use a sign at a particular location should be made on the basis of either an engineering study or the application of engineering judgment. Local jurisdictions that do not have engineering staff knowledgeable of the MUTCD should seek assistance from their State transportation agency, another jurisdiction, or traffic engineering consultant. The Local Technical Assistance Program (LTAP) in each State and tribal area can be a valuable resource for this assistance as well.
Traffic Sign Types
The MUTCD specifies three classes of signs defined by their function:
- Regulatory signs.
- Warning signs.
- Guides signs.
The rules of the road—the laws and regulations—are often communicated through regulatory signs. These are important signs to maintain because the absence of, or damage to, a regulatory sign could result in or contribute to a severe crash.
Regulatory signs are usually a combination of black, white and red colors as shown by these examples.
Damaged or missing regulatory signs (especially the STOP, YIELD, ONE WAY, and DO NOT ENTER signs) should be replaced or repaired within hours of the agency having notice of them missing, down, or damaged.
Warning signs are important because they provide drivers with advance notice of potentially hazardous situations or conditions of the road ahead that may not be apparent. They are particularly helpful to motorists who are unfamiliar with a particular road.
Warning signs, such as these, have a yellow background.
Damaged or missing warning signs should be repaired or replaced as soon as possible. As a general rule, deficiencies should be corrected within three days of notice.
Guide signs are used for driver navigation—to help a driver to get to a particular destination. There are a variety of guide signs that display route designations, destinations, directions, distances, services, points of interest, and other geographical, recreational, and cultural information. The absence of these signs could cause motorists to miss their route and destination, resulting in less than efficient navigation. It can also lead to erratic maneuvers, such as slowing or stopping in the roadway and making abrupt turns. For local roads and streets, common guide signs include: street name signs, route signs, and destination and distance signs. General service signs, e.g. the hospital symbol, and general information signs, e.g. the library symbol, are included within the guide sign group.
Street name sign
Guide signs are usually white legend on a green background, but can be other backgrounds, such as brown or blue.
Replacement of damaged or missing guide signs should be done within approximately seven working days from notice, recognizing that timing of the replacement is dependent upon how critical the sign is. For example, a street name sign is essential for emergency responders to find streets and locations on those streets. Also, since many guide signs have to be specially fabricated due to the variation in the sign message, it may take a few days before they can be assembled or purchased.
Signs in Work Zones
Whenever there is construction, utility work, or maintenance being done on the road or roadside, temporary traffic control is necessary, which usually includes temporary warning signs. The warning signs used for this purpose have a black legend and border on orange background. While these are temporary signs, it is important that they be maintained because travel through work zones can be hazardous due to unusual or different conditions that drivers may not expect. These signs should not be allowed to deteriorate much below their original condition. For more information on this topic refer to the MUTCD, Part 6. Appendix C provides three typical traffic control applications from the MUTCD that would likely be used for sign maintenance activities.
In most cases warning signs such as these have an orange background. (Note: for the signs on left and center, the word AHEAD or the distance [e.g., 500 FT] would fit within the dashed lines.)
The response time frames for correction of missing or damaged signs mentioned above are provided to illustrate relative priority in providing sign maintenance activities. Each agency should adopt a policy that addresses sign repair response procedures and times both for normal work periods as well as after hour needs.
A basic understanding of the materials that make up a sign is needed to carry out a good maintenance program. This section provides a brief overview of the materials for the sign face and the sign backing.
Sign Face Sheeting
The sign face consists of film material, called sheeting, which is comprised of glass beads or microprisms to provide visibility at night. Highway signs, that are not illuminated by external lights, are visible at night because they have sheeting made of retroreflective material. Retro-reflection is a type of reflection that redirects incident light from the sign face back to the source—the vehicle headlights.
Retroreflection is achieved through either glass beads or microprisms imbedded in the sheeting.
Over time manufacturers have developed different types of sheeting to accomplish retroreflection, initially using small glass beads, but now more commonly using microprisms with various angular designs. Sheeting manufacturers have specific brand names for their materials. ASTM International has classified the different types by conformance to the retroreflectance properties, color, and durability. The types for rigid surface signs are as follows:
ASTM has established new sheeting specifications for minimum retroreflectivity values, called ‘coefficient of retroreflection’ (RA) for each sheeting type. RA is a quantitative measure and is expressed in metric units of candelas per lux per square meter (cd/lx/m2). The specification provides an initial RA value for a prescribed entrance angle and observation angle—common angles within an instrument that measures RA and relates somewhat to roadway/vehicle geometries. Minimum RAs for the various sheeting types of white, yellow, fluorescent yellow, green and red color sheeting used for permanent rigid signs at the common angle readings of -4 degree entrance angle and 0.2 degree observation angle—angles typically set for measuring RA in a portable instrument (see pg. 27) are shown in Table 1.
Table 1. Minimum Coefficient of Retroreflectivity (RA) for Several Types of New Sheeting Used for Rigid Signs
Source: ASTM Standard Specification D4956-09
The values shown in Table 1 are for newly purchased sign sheeting. Exposed to the sun and weather over time, the colors will fade and the retroreflective qualities of the sign sheeting will deteriorate to such an extent that the sign will no longer be readable, both day and night, at a distance needed by the driver. The 2009 MUTCD includes a requirement for minimummaintained retroreflectivity levels for most traffic signs. These values are shown in Table 2 for certain types of permanent signs most commonly found on local, non-freeway roads.
Table 2. Minimum Maintained Retroreflectivity Levels for Specified Signs.
* White to red contrast ratio shall be at least 3:1.
Based on the values in Table 2, Type I sheeting material should not be used for warning signs and for the white legend on green background guide signs because it does not provide the retroreflectance level required by the driver. The higher level sheeting types will provide a brighter sign and in general have a longer service life, allowing for an overall cost savings.
Agencies will have until January 2012 to establish and implement a sign assessment or management method in compliance with the 2009 MUTCD to maintain minimum levels of retroreflectivity. The compliance date for replacing signs that do not meet minimum requirements is January 2015, except for street name signs, which is January 2018.
To learn more about sign materials and especially sign retroreflectivity, visit the following FHWA web site: www.fhwa.dot.gov/retro.
The retroreflective sheeting material is applied to the rigid sign backing (also known as the substrate), which can be aluminum, wood, or a composite plastic. Aluminum is by far the most commonly used material. The aluminum backing can be reused often, reducing the cost of signing and can be recycled easily to recoup a small portion of the cost.
Plywood is used occasionally for temporary signs because it can be cheaper and is lighter than aluminum. Fiberglass-reinforced plastic materials are used infrequently because of their handling and recycling issues.
Most agencies use aluminum for sign backing.
Any device that is used to display the traffic sign is known as the sign support, which consists of the vertical post and, if needed, any stiffeners onto which the sign panel is attached. Most posts for roadside post-mounted signs are one of the following types:
A sign support can become a deadly hazard when struck by a vehicle that drives onto the roadside; therefore, there is an MUTCD standard that requires all roadside sign supports in the clear zone (see Appendix B for description of clear zone) to be breakaway, yielding, or shielded by a barrier or crash cushion. ‘Breakaway’ is a term to describe crash tested sign supports that break or bend upon impact. This includes sign supports that, when struck by a vehicle, separate from the base and are knocked ahead of or up and over the errant vehicle. A ‘yielding’ support refers to a support that bends, allowing a vehicle to run over it. Barriers are typically not installed to shield roadside signs, especially on local roads; hence, the design of the post, regardless of the type, must provide the breakaway or yielding feature. All sign supports on highways within the clear zone must either be of a breakaway type meeting the crashworthiness criteria of NCHRP 350 (see references) or be shielded by guardrail, barrier, or an energy absorbing system meeting NCHRP Report 350 or the AASHTO Manual for Assessing Hardware (MASH) criteria. Additional information on acceptable breakaway sign supports can be found at FHWA’s Office of Safety website:http://safety.fhwa.dot.gov/roadway_dept/policy_guide/road_hardware/breakaway/signsupports.cfm.
Wood posts are frequently used, especially in regions where wood is economical compared to metal type supports. These posts usually come in sizes of 4 x 4 inches to 6 x 8 inches. All posts above 4 x 4 inch nominal size must be drilled perpendicular to traffic flow to allow the post to break away if struck by a motor vehicle.
Small supports have a cross section of approximately 16 square inches. This type of post should be buried about 30 to 36 inches deep depending upon the type of soil and backfill; check State specifications or with LTAP for embedment depth and backfill material. The post may need to be buried even deeper to reduce vandalism and reduce dislodging by heavy winds. One or two posts may be used to make up the sign support, but adding posts too close together can affect crashworthiness.
Small wood support is typically a 4 x 4 inch post.
Large supports should be drilled to provide the breakaway characteristic. For example, a 6 x 8 inch wood post can be used if the cross section is weakened by drilling two 3-inch holes (drill perpendicular to roadway). A 4 x 4 inch wood post is the largest undrilled wood post recommended to act as a breakaway support.
Holes are needed for wood posts greater than 4 x 4 inches.
U-Channel Steel Post
The U-channel, hot rolled steel post is another common small sign support. It is considered breakaway since it will bend, break or pull out of the ground when it is hit.
Post Support. The post should be driven into the ground and not encased in concrete. A broken or damaged post is easier to remove if it is not driven or set into the ground more than 3.5 feet.
Typical u-channel post.
Breakaway Devices. A U-channel post of re-rolled rail steel weighing 3 pounds-per-foot or less meets breakaway requirements by itself. If a heavier post is used, splices can be purchased commercially to install at ground level; alternatively a stub post of the same material can be set in a concrete base with a 4-inch length available to bolt to the sign post as a base connection. These devices improve safety when the post is hit, will make repair easier, and will make it possible to use a U-channel post when it has to be placed in a concrete area.
Breakaway treatments for u-channel posts.
Square Steel Tube
Another sign post is the square steel tube (perforated) design, which is used in many localities. Posts of this type are also considered breakaway if they are 2 ¼ inches or less in size.
Post Support. Posts can be driven into the ground. Do not place concrete around the post. A broken or damaged post is easier to remove if it is not driven or set into the ground more than three feet.
Typical square steel post.
Breakaway Devices. As with the U-channel post, sleeve assemblies can be used for the base or slip couplings can be used near the base. These devices will increase the safety of a sign if it is hit and make it easier to repair. After the sign has been hit, the broken stub of the post can be removed from the base sleeve and a new sign post put back in place.
Two types of breakaway designs.
I-Beam Steel Post
This post type is used when it is necessary to support large sign panels, which is common for roadside post-mounted guide signs.
All large steel posts use a breakaway feature, unless protected by barrier or placed out of the clear zone. This is usually accomplished by using a slip base that connects the post to the foundation. When struck, the post slips off the foundation at the bottom, and rotates around the hinge plate below the sign panel. This allows the vehicle to safely pass under the sign after impact.
I-beam steel posts with a slip base are needed for larger roadside guide signs.
There are many other products available commercially for sign supports. Use depends on local requirements and costs. This publication only shows four of the most common types of small sign supports. The comprehensive guide to breakaway sign supports is A Guide to Small Sign Support Hardware.
Location and Height of Signs
When installing a sign for the first time or as a replacement to an existing sign, the sign technician should be aware of the requirements for its position on the roadside. Signs are positioned longitudinally along the road, laterally from the edge of the road, and vertically above the ground. If a sign replacement is warranted, the sign technician should not assume the original sign was placed correctly. It is important to check the location of the support and the mounting height of the sign above the roadway to ensure the sign is visible and crashworthy.
The longitudinal location of the sign is dictated by the sign type and the specific situation. There are too many different situations to cover in this guide, so refer to the current edition of the MUTCD, your State standards and/or directives, and your agency’s requirements.
The figures on the next page represent the recommended height and lateral location as provided in the MUTCD.
WHEN INSTALLING A NEW SIGN CHECK WITH YOUR UTILITY COMPANY AND ANY OTHERS WHO MAY HAVE UNDERGROUND CABLES AND CONDUITS.
To obtain maximum retroreflection from traffic signs, yet eliminate specular glare, signs should be correctly aligned. Specular glare is the mirror type reflection characteristic of any glossy surface. Under severe circumstances, such as direct sunlight, specular glare can make the sign legend unreadable. Often this becomes apparent from driver complaints. To avoid the occurrence of specular glare, signs should be positioned slightly more than perpendicular to the roadway (93 degrees is recommended by sheeting manufacturers).
When signs are out of proper alignment, they will not be as visible at night.
o achieve the desired goal of quality sign maintenance, a comprehensive sign management system should be developed and followed. The elements of a sign management system include:
When these elements are in place and followed, the agency can be assured that the signs on their roads are functional and meet the needs of the road users.
Each of these elements will be discussed separately in the following chapters.
Knowing what signs are on your roads allows the agency to develop a systematic sign maintenance program as well as to determine the amount of resources that will be needed to provide the desired level of traffic sign maintenance activities contained within the agency’s sign maintenance policies. An inventory can serve many purposes:
Inventory systems can be simple manual card systems, but with the availability of several inexpensive and even free computer software packages, computer-based inventories are much more effective and are easy to use. Also by using global positioning systems (GPS) technology, signs can be easily and accurately located and mapped on geographic information systems (GIS). Computerized sign inventories are available through sign vendors or your Local Technical Assistance Program. An example of sign inventory can be found at the Utah LTAP website: http://www.utahltap.org/.
With a computerized sign inventory, the sign technician can easily record data while in the field.
The key to a successful inventory program is collecting the appropriate data elements and keeping it up to date. Table 3 shows the data elements that should be considered when developing an inventory.
Table 3. Data Elements for Sign Inventory.
Sign dating labels with anti-vandalism warnings can be applied to the back of the sign.
Timely detection of and response to maintenance needs are critical elements of an effective sign management system. This can be accomplished through periodic inspections of your signs to ensure they are still there, are needed, and are performing as intended both day and night.
Sometimes, defective signs can be identified through informal methods including:
When your agency receives notice of any sign deficiency from any of the above methods, it should be recorded and attended to within the appropriate priority for the type of sign involved.
In addition to the informal detection methods, the agency's formal inspection program should include:
ALUMINUM ALLOY 3105
3105 is an essentially 98% pure aluminum alloy with minor additions for strength. It is not hardenable by heat treatment, and has excellent formability, corrosion resistance and welding characteristics.
3105 is commonly used for building products.
ALUMINUM ALLOY 5052
5052 is one of the higher strength non-heat-treatable alloys. It has a high fatigue strength and excellent corrosion resistance, particularly in marine atmospheres. The form-ability of the grade is excellent and in the annealed condition it offers higher strengths than 1100 or 3003 grades. One of the most popular alloys.
5052 is often used in high strength sheet metal work, marine components, appliances, fuel and oil tubing, signs, trucks bodies and electrical cabinets.
We can Ship Traffic Signs, Road Signs, Regulatory Signs, Parking Signs, Warning Signs, Street Signs, Property Signs Anywhere in the USA
Alabama, Montgomery (AL) Alaska, Juneau (AK) Arizona, Phoenix (AZ) Arkansas, Little Rock (AR) California Sacramento (CA) Colorado, Denver (CO) Connecticut, Hartford (CT) Delaware, Dover (DE) Florida, Tallahassee (FL) Georgia, Atlanta (GA) Hawaii, Honolulu (HI) Idaho, Boise (ID) Illinois, Springfield (IL) Indiana, Indianapolis (IN) Iowa, Des Moines (IA) Kansas, Topeka (KS) Kentucky, Frankfort (KY) Louisiana, Baton Rouge (LA) Maine, Augusta (ME) Maryland, Annapolis (MD) Massachusetts, Boston (MA) Michigan, Lansing (MI) Minnesota, St. Paul (MN) Mississippi, Jackson (MS) Missouri, Jefferson City (MO) Montana, Helena (MT) Nebraska, Lincoln (NE) Nevada, Carson City (NV) New Hampshire, Concord (NH) New Jersey, Trenton (NJ) New Mexico, Santa Fe (NM) New York, Albany (NY) North Carolina, Raleigh (NC) North Dakota, Bismark (ND) Ohio, Columbus (OH) Oklahoma, Oklahoma City (OK) Oregon, Salem (OR) Pennsylvania, Harrisburg (PA) Rhode Island, Providence (RI) South Carolina, Columbia (SC) South Dakota, Pierre (SD) Tennessee, Nashville (TN) Texas, Austin (TX) Utah, Salt Lake City (UT) Vermont, Montpelier (VT) Virginia, Richmond (VA) Washington, Olympia (WA) West Virginia, Charleston (WV) Wisconsin, Madison(WI) Wyoming, Cheyenne (WY)