Notice 

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 authors, who 

are 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. 
i 

1. Report No. FHWA 

FHWA-SA-09-025

2. Government 

Accession No.

3. Recipient’s Catalog No.

4. Title and Subtitle

Maintenance of Signs and Sign Supports: A Guide for Local 

Highway and Street Maintenance Personnel

5. Report Date

January 2010

6. Performing Organization 

Code

7. Authors

Hugh W. McGee, P.E.

8. Performing Organization 

Report No.

9. Performing Organization Name and Address

Vanasse Hangen Brustlin, Inc. 

8300 Boone Boulevard, Suite 700 

Vienna, VA 22182-2626 

10. Work Unit No.

11. Contract or Grant No.

DTFH61-05-D-00024

12. Sponsoring Agency Name and Address

Office of Safety

Federal Highway Administration

U.S. Department of Transportation

1200 New Jersey Avenue, S.E.

Washington, D.C. 20590

13. Type of Report and 

Period Covered

Final Report

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.

16. Abstract

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)

Unclassified

20. Security Classif. (of 

this page): Unclassified

21. No. of 

Pages: 58

22. Price

Form DOT F 1700.7
ii

ACKNOWLEDGEMENTS 

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 Oversight Working 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. 
iii

TABLE OF CONTENTS 

I. INTRODUCTION ............................................................................... 1

II. SIGN PRINCIPLES AND TYPES .................................................... 2

III. SIGN MATERIALS .......................................................................... 7

IV. SIGN SUPPORTS ........................................................................... 11

V. SIGN INSTALLATION .................................................................. 17

VI. SIGN MANAGEMENT SYSTEM ................................................ 20

VII. INVENTORY ................................................................................. 21

VIII. INSPECTION ............................................................................... 25

IX. PREVENTIVE MAINTENANCE ................................................. 29

X. REPAIR AND REPLACEMENT ................................................... 35

XI. REPORTING AND RECORD KEEPING .................................... 41

REFERENCES AND OTHER SOURCES OF INFORMATION ..... 44

APPENDIX A: MATERIALS AND EQUIPMENT USED IN 

MAINTAINING SIGNS ...................................................................... 46

APPENDIX B: CLEAR ZONE DESCRIPTION ................................ 49

APPENDIX C: THREE TYPICAL WORK ZONE LAYOUTS 

FROM MUTCD .................................................................................... 51
1

I. INTRODUCTION 

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. 

 Materials. 

 Supports. 

 Installation. 

 Management System. 

 Inventory. 

 Inspection. 

 Preventive 

Maintenance. 

 Repair and 

Replacement. 

 Recordkeeping. 

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. 
2

II. SIGN PRINCIPLES AND TYPES 

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 key principles 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. 
3

 Guides signs. 

Regulatory 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

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. 
4

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

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. 
5

 

Destination sign Street name sign 

Hospital 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 
6

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.
7

III. SIGN MATERIALS 

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. Retroreflection 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 
8

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: 

 Type I – commonly referred to as engineering grade and 

typically made as an enclosed lens sheeting. 

 Type II – commonly referred to as super-engineering grade 

and also typically made of glass beads. 

 Type III – commonly referred to as high intensity and can 

be made of encapsulated glass beads or microprisms. 

 Types IV, VIII, IX and XI—no common identifier but 

referred to as prismatic with the differences related to the 

varying angles of the microprisms. 

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 RA’s 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. 
9

Table 1. Minimum Coefficient of Retroreflectivity (RA) for 

Several Types of New Sheeting Used for Rigid Signs. 

Sheeting

Type

Coefficient of Retroreflectivity for

0.2 deg Observation and -4 deg Entrance Angles

White Yellow

Fluorescent

Yellow

Green Red

I 70 50 N/A 9 14

II 140 100 N/A 30 30

III 250 170 N/A 45 45

IV 360 270 220 50 65

VIII 700 525 420 70 105

IX 380 285 230 38 76

XI 580 435 350 58 87

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 minimum 

maintained 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. 
10 

Table 2. Minimum Maintained Retroreflectivity Levels for 

Specified Signs. 

SIGN 

CLASS SIGN COLOR

BEADED 

SHEETING

PRISMATIC 

SHEETING

I II, III III, IV, VIII, IX, 

XI

Guide White on 

Green

(Ground Mount 

Only) 

White Do Not 

Use

≥ 120

Green ≥ 7 ≥ 15

Warning Yellow ≥ 48 in. or

Bold 

Symbol

Do Not 

Use

≥ 50

< 48 in. Do Not 

Use

≥ 75

Regulatory White on Red * White ≥ 35

Red ≥ 7

Black on White White ≥ 50

* White to red contrast ratio shall be at least 3:1. 

Source: Modified from MUTCD, 2009 

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. 
11 

Sign Backing 

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. 
12 

IV. SIGN SUPPORTS 

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: 

 Wood post. 

 U-channel steel post. 

 Square or round tube steel post. 

 I-beam steel post. 

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_hard

ware/breakaway/signsupports.cfm.
13 

Wood Post 

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. 

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. 

Small wood support is 

typically a 4 x 4 inch post.

Holes are needed for wood 

posts greater than 4 x 4 

inches.
14 

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. 

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. 

Typical U-channel post.
15 

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 1⁄4 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. 

Breakaway Devices. As with the Uchannel 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. 

Typical square steel 

post.
16 

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.
17 

V. SIGN INSTALLATION

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.
18 

Source: MUTCD, 2009
19 

Positioning Signs 

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.
20 

VI. SIGN MANAGEMENT SYSTEM 

To 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: 

 

 Inventory—a manual or computer-based database of signs 

installed on your roads. 

 Inspection—a program for scheduled inspection of signs. 

 Preventive Maintenance—activities that will ensure that 

signs will attain their full service life. 

 Repair and Replacement—a program and process for 

either repairing or replacing non-functional signs. 

 Reporting and Record Keeping—a process for keeping 

record of all maintenance activities. 

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. 
21 

VII. INVENTORY 

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: 

 Sign Life—when signs are installed, the installation date is 

labeled or recorded so that the age of a sign is known. 

Signs degrade over time and when combined with 

periodic night time inspections, an agency could 

determine when a sign has reached the end of its useful 

life. 

 Manage and prioritize— an inventory that records the 

location of signs and recent maintenance activities can help 

establish the following: 

 Where a single sign needs to be replaced. 

 If a corridor needs sign improvements. 

 When to clear back brush away from signs. 

 Minimizing tort liability—an inventory can document the 

inspection and maintenance activities. 

 Budgeting—an inventory can help manage resources for 

sign replacements on an annual or as-needed basis. 

 Efficiency—combining work orders with the inventory 

allows the monitoring of signing activities and scheduling 

of maintenance activities. 

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). 
22 

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. 
23 

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. 

DATA ELEMENT DESCRIPTION

Sign Identification Number Unique number identifying sign

Location Route name, distance, etc. depending on 

location reference system; could also be GPS 

latitude/longitude

Sign Code Usually MUTCD designation

Sign Position Location of sign relative to road (left, right, 

overhead)

Offset Distance from edge of pavement

Height Height of sign above road level

Sign Size Width and height of sign

Sheeting Type Grade of retroreflective material

Installation Date Date when sign installed

Post/Support Type Type of sign support (e.g. wood, tube)

INSPECTION ITEMS

Sign Condition Quality of sign based on visual inspection

Retroreflectivity Measured value or visual assessment condition

Maintenance Activity Type of maintenance last performed

Inspection/Maintenance 

Date

Date when sign was last inspected or 

maintained

Inspector Name or initials of person who inspected or 

maintained sign

Comments Supplementary notes about the sign
24 

Sign dating labels with anti-vandalism warnings can be 

applied to the back of the sign. 
25 

VIII. INSPECTION 

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: 

 Agency’s employees—train all staff to look out for any 

signing deficiencies and report their finding. 

 Police patrols—establish a procedure whereby the police 

department notifies you of any sign problems. 

 Citizen inputs—do not overlook the importance of having 

citizens contact your agency when they observe problems; 

having a phone number on the sign dating sticker on the 

sign is recommended for this purpose. 

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: 

 Training of sign technicians—train all maintenance staff 

on what to look for and how to detect the various sign 

deficiencies. 

 Inspection schedule—inspect signs and supports 

routinely. All agencies should establish a policy for when 

inspections would occur, taking into consideration the 

level of importance for the signs, road type or traffic 

volumes. 
26 

 Inspection procedures—the details of how an inspection is 

to be performed should be prescribed by the agency and 

used for training of its staff. 

 On-the-spot repair/replacement—many deficiencies may 

be resolved immediately; this requires that the 

maintenance technician has the necessary equipment, 

replacement parts, and signs on hand. 

 Preparation of work orders to correct problems—a system 

of work orders should be used for more time consuming 

repairs. 

 Recordkeeping—having a record of the inspection and 

repairs is critical to a successful sign management system 

and will be a valuable asset for your risk management 

program and tort defense. 

A traffic sign can be found deficient for a variety of reasons (see 

Sign Inspection Checklist, on pg 28), including the degradation of 

night time visibility. There is now a standard in the MUTCD that 

requires that all agencies have a maintenance program in place by 

2012 to maintain minimum levels of traffic sign retroreflectivity. 

Regulatory, warning and many guide signs will need to be 

replaced when they degrade below the established minimum 

levels of retroreflectivity presented in Chapter III. Your agency 

can meet these requirements by having an inspection program 

that will identify when signs need to be replaced. 

There are alternative methods for inspecting signs for adequate 

retroreflectivity levels; they include: 

 Measuring the sign’s retroreflectivity level with a 

retroreflectometer. 

 Visually comparing the sign with a test panel that has a 

retroreflectivity level set at the minimum requirement. 

 Visually inspecting the sign and making a subjective 

judgment by a trained inspector as to its adequacy. 
27 

The first method is the most 

accurate, but it is time consuming 

and many agencies cannot afford 

the needed retroreflectometer, 

which costs about $10,000. 

However, you may consider 

borrowing one from your State 

DOT or LTAP. The second and third 

methods can be effective if the 

inspector is adequately trained. The 

inspection should be done at night. 

More details on these procedures 

can be found in Methods for 

Maintaining Traffic Sign 

Retroreflectivity, and the reader may 

want to contact their State 

LTAP/TTAP center for alternative 

inspection methods. 

 

Remember, night reviews are still important. While a sign may 

appear adequate during the day, it may be non-visible at night. 

A retroreflectometer 

can be used to 

determine if a sign 

meets or exceeds the 

minimum required 

retroreflectivity level.
28 

Sign Inspection Checklist 

 Is the sign needed? 

 Is the sign missing? 

 Is the sign the correct one; is it in accordance with 

MUTCD? 

 Is the sign correctly positioned with respect to: 

 Lateral clearance? 

 Height above ground? 

 Longitudinal placement along road? 

 Is the sign visible, both day and night, at the required 

distance? (Indicate cause of problem if not [e.g. blocked 

by vegetation, other signs, etc.]). 

 Check the sign face for: 

 Condition (e.g. cracking, delamination, etc.) 

 Fading or discoloration 

 Contrast 

 Retroreflectivity 

 Damage or vandalized (graffiti, bullet holes, etc.) 

 Is sign support break-away or yielding? If not, are sign 

supports located to outside the clear zone? 
29 

IX. PREVENTIVE MAINTENANCE 

The inspection process just discussed will identify sign and sign 

support deficiencies that will require appropriate repair or 

replacement. In addition, there are certain ‘preventive’ 

maintenance activities that may be needed to keep signs and their 

supports fully functional; these include: 

 Sign cleaning. 

 Vegetation control. 

 Anti-theft measures. 

 Sign support adjustments. 

Sign Cleaning 

Usually, it is not necessary to clean the sign face as periodic rain 

will help clean the sign. However, localized conditions, especially 

in urban areas, may cause the sign to become less visible due to 

the buildup of dirt, grime, mildew, or mold. Locations where sign 

cleaning may be warranted include: 

 Signs under trees. 

 Signs along routes with heavy truck traffic. 

 Areas with infrequent rainfall. 

 Signs in industrial areas. 

Also, before deciding to replace a sign because of observed low 

night time visibility, the sign life might be extended simply with 

cleaning. 
30 

Signs under a tree canopy are often covered with mold 

(left photo) which can easily be cleaned (right photo, 

right half of sign).

When cleaning a sign a non-abrasive cleaner free of damaging 

solvents should be applied with a sponge or soft bristle brush. 

Pressure sprayers may be used if not sprayed so close to the sign 

that it would damage the sheeting face. Whatever procedure is 

followed, it is best to first check with the product supplier and test 

out any chemical cleaner on a sign in the maintenance yard before 

use in the field. 

Vegetation Control 

One of the common deficiencies found during an inspection is 

partial or full blockage of the sign by roadside vegetation. During 

the spring and summer seasons, fast growing weeds can quickly 

cover a sign as will tree branches and brush. If sign inspections 

are done during these seasons, these situations should be readily 

identified. And, if the technician has suitable equipment, it can be 

rectified during the inspection. The topic of vegetation control is 

more thoroughly discussed in the FHWA field guide entitled, 

Vegetation Control for Safety, A Guide for Local Highway and Street 

Maintenance Personnel. 
31 

The warning sign (circled) is only partially 

visible in the spring. By mid-summer, it will 

be completely hidden by vegetation. 

Anti-theft Measures 

Unfortunately, signs are occasionally stolen for any number of 

reasons. This can be avoided by making it difficult to remove a 

sign and by enacting laws to penalize vandals. Specific fasteners 

can be used to attach signs to support posts which make it far 

more difficult for vandals to remove sign panels. Among the more 

common special fasteners in use are: 

 Expanding anchor bolts and blind aluminum rivets. 

 Bolts (or nuts) that require special tools to install and 

remove them (such as fluted nuts or star bolts). 

 Nuts with shear-off heads. 

 Simply hammering down the excess portion of the 

threaded bolt so that it cannot be easily unscrewed. 
32 

Simple details of anti-theft

/anti-vandal fasteners.

Expanding anchor and blind 

aluminum rivets.

Fluted nuts (double pyramid 

shape).

Shear off heads.

Bent over bolts.

Sign Supports 

Preventive maintenance activities that deal 

with the entire sign to include the sign 

support, include: 

1. Ensuring the sign post is still firmly 

placed in the ground. During formal 

or informal inspections of signs, a sign 

leaning away from the vertical will 

likely indicate that the sign post is no 

Visibility of sign 

will diminish if not 

vertically straight.
33 

longer stabilized in the ground or not properly attached to the 

slip base. 

2. Maintaining the sign 

crashworthiness by not adding 

additional unnecessary supports 

and braces. The sign, pictured to 

the right, has multiple posts 

supporting it when two are 

probably enough. Also, two 

horizontal braces cross the bottom. 

These increase the strength of the 

support greatly, but a small car 

hitting this is likely to stop 

suddenly, causing severe damage. 

Larger posts with breakaway mechanisms at the ground 

would be the safe construction. 

3. Positioning the sign so that it is not frequently hit or adding a 

marker to increase its visibility. Signs placed at the near end of 

a median island are frequently knocked down because of the 

tight radius for large vehicles to stay within the designated 

lane. Preventive measures include moving the sign back a few 

feet from the end and placing an object marker on the post, 

which increases the visibility of the sign structure. 

Knockdowns of signs in the median may be avoided with use 

of an object marker. 

Too many posts and 

braces can be a safety 

hazard.
34 

4. The environment can also be a factor on the safety 

characteristics of sign supports. The two most common 

conditions that can affect the crashworthiness of a sign 

support are erosion of soil at the base and the growth of trees 

around the support. 
35 

X. REPAIR AND REPLACEMENT 

Traffic signs will require repair or replacement for any one of a 

number of reasons including: 

 Vandalism. 

 Hit by vehicle. 

 Relocated and/or adjusted by private individuals. 

 Damage by weather or other natural factors. 

 Reached its useful life. 

When a traffic sign requires repeated maintenance, consideration 

should be given to the reason why the problem exists. 

Although sign vandalism in some cases seems to be an 

overwhelming problem, it is a situation that cannot be ignored. 

Examples of sign vandalism include sign stealing, over painting, 

and bullet holes. Also, signs are often severely bent or knocked 

down by vehicles running off the road and hitting the sign, which 

is why crashworthy sign supports should be used. Signs can be 

bent, twisted, knocked down or even blown away by strong 

winds. Finally, signs will eventually become ineffective, when 

they have reached their service life, because the colors have faded 

and/or the retroreflectivity level is below the minimum required 

for that type of sign. 

When signs are damaged by vandalism, by a vehicle hit, or by 

weather factors, the sign technician must determine if the sign 

should be repaired, replaced, or left as is. This is usually a field 

judgment. More often than not, it is cheaper to replace a badly 

damaged or unreadable sign than attempt many repairs in the 

field. When determining whether or not to conduct repairs in the 

field, the technician should consider the repair costs, remaining 

service life of the sign face after repairs and the value of the sign 

blank (when it is reusable) against replacing it with a new or 
36 

recycled sign. A sign technician should not leave a sign down or 

take a damaged sign away and leave nothing in its place. The 

technician should always have a replacement sign or sufficient 

repair materials while working in the field. If a field repair is 

appropriate or repair of the sign is needed until a replacement 

sign can be obtained, consider the following tips while performing 

the work. 

Field Repair of Bent Signs

Signs may be bent such as this 

STOP sign pictured at right. While 

many bent signs can be read in the 

daylight, some bent signs, even 

signs with minor bending, are 

difficult to see at night because they 

no longer reflect the light from the 

vehicle's headlights back to the 

driver's eyes. Minor bending like 

this may be repaired by removing 

the sign from the post and 

straightening the sign face.

Bent signs can be 

repaired in the field

If after straightening the message remains clear, legible, 

retroreflective and the sign surface is not opened, cracked or 

separated from the sign face, it may be reused. Remember, if a 

sign is so badly bent that it will take several hours to fix, it is often 

cheaper to replace the sign and leave any repair or salvage to a 

shop operation. To repair a sign with minor bends: 

1. First try to straighten the sign. If possible, bend the sign 

back in place on the sign post with hand pressure (wear 

leather gloves). 

2. If the sign cannot be straightened sufficiently with hand 

pressure, remove the sign from the support and place it on 

a flat surface such as a truck bed, trailer bed, or fender 

dolly. Use cardboard or cloth to protect the sign face and 
37 

pound it flat with a rubber mallet. (The cloth and rubber 

mallet will minimize further damage to the reflective 

sheeting.) 

3. If the sign is no longer serviceable, replace it immediately 

if it is a regulatory or warning sign. If a replacement sign is 

not immediately available, remount the existing sign until 

you return later with a satisfactory replacement. 

Field Repair of Scrapes and Holes

Signs with scraped faces (usually as a result of being hit) or signs 

that have holes in them (typically as a result of gunshot 

vandalism) are often no longer legible, particularly at night. The 

damaged areas no longer reflect light back to the driver. 

This sign has been hit by several 

gunshots. Even with the holes 

the sign can be read during the 

day and functions as intended, 

but leaving a sign up in this 

condition does not convey a 

serious message and may 

encourage more gun shots to 

this and other signs. The sign 

should be replaced or repaired 

as soon as practical. Minor 

damage can often be repaired in 

the field. 

Field patching can be done by preparing a repair kit that includes 

the appropriate colors and types of new sheeting materials 

(including pressure-sensitive adhesive sheeting), cleaners and 

sealants. To repair a sign with scrapes or a few holes: 

Signs with extensive gunshot 

holes should be replaced.
38 

1. The sign should first be straightened and any bullet holes 

pounded flat using cardboard or cloth to protect the sign 

face and pound it flat with a rubber mallet. 

2. Clean the area(s) to be patched with Xylol, then Varnish 

Naphtha. 

3. If you carry replacement sign faces or patching materials, 

make sure that the retroreflective material being used for 

patching is the same as the material on the face of the sign. 

If in doubt about what type of sheeting to use replace the 

sign. 

4. Follow the manufacturer's recommendations when 

making field patches. Cut background field patches 

slightly larger than the damaged area. Pressure sensitive 

material should be extended at least 1/2-inch beyond the 

damaged area. 

5. Replace the damaged legend with diecut, pressure 

sensitive, pre-spaced letters, borders and symbols and 

firmly squeegee into place. 

6. Seal the hole on the back of the sign by applying 

aluminum foil tape to stop moisture from reaching the 

adhesive on the sign sheeting patch. For large holes, start 

placing the foil at the bottom of the hole, overlapping 

about 1/2-inch in a shingle fashion as you move up 

covering the hole. 

7. If the sign is subject to snow burial and the replacement 

sheeting extends to the top edge of the sign, place 

transparent film along the top edge to seal out any 

moisture. Of course, if signs can be relocated to an area to 

avoid snow burial, they should be. 

.
39 

Field Removal of Spray Paint on Signs

This sign shown to the left has been 

sprayed with black paint. Everyone who 

looks at the sign notices it. At night the 

message becomes hard to read. The safety 

effectiveness of this sign is significantly 

reduced and requires immediate 

attention. 

Overpainted signs can often be cleaned, 

however, many cleaning materials will 

damage the sign face materials which will 

result in the need to replace the sign. 

There are several approaches to 

overpainted signs. All these approaches work to varying degrees 

to help reduce and control this problem. Generally a combination 

of these approaches is recommended for communities with 

recurring or increasing vandalism problems. 

Paint can sometimes be removed from the face of signs without 

damaging or reducing the sign's retroreflective properties. Several 

manufacturers have developed sign protective overlays that are 

more tolerant to paints and cleaning agents, and they have also 

developed improved cleaners. 

Paint should not be removed with abrasive compounds or 

implements that will leave the sign face scratched (e.g., steel 

wool). After cleaning off paint, signs should be inspected under 

night conditions or measured to determine if they have retained 

sufficient retroreflective characteristics to remain legible at night. 

Sign damaged by 

overpainting.
40 

Sign has Reached or Exceeded its Service Life.

Over time the colors of the sign facing will fade—especially for 

signs facing south towards the sun—reducing the contrast level 

between the legend and the background, and the sheeting’s 

retroreflectivity properties will diminish, such that the sign can no 

longer be seen and read by the driver from an adequate distance. 

Under either condition the sign has reached its service life and 

should be replaced. 

As mentioned in Chapter III, there is a new standard in the 

MUTCD for maintaining sign retroreflectivity and contrast levels. 

By January 2015, agencies are required to replace regulatory, 

warning and ground-mounted guide signs (except street name 

signs) that fall below the minimum requirements. By January 

2018, the replacement requirement extends to street name signs 

and overhead guide signs.

As noted earlier the agency’s inspection program should be able 

to identify signs that need to be replaced for this reason. Also 

mentioned earlier is the possibility of cleaning the sign to extend 

its useful life. 

An agency can program the replacement of signs due to low levels 

of retroreflectivity by methods other than a field inspection, 

including: 

 Based on expected sign life—the sign is replaced when it 

has reached its expected life, which is based on the 

experience of retroreflectivity degradation in the 

geographic area. 

 Blanket replacement—all signs in an area or route, or of a 

given sign type are replaced at specified time intervals. 

 Control signs—replacement of signs in the field is based 

on the performance of a sample set of signs placed and 

monitored in the maintenance yard.
41 

XI. REPORTING AND RECORD KEEPING 

In this day and age the job is not over until the paperwork is 

complete. The importance of keeping good, up-to-date records of 

maintenance activities cannot be overstated. Aside from making 

the agency’s management program more effective and efficient, 

record keeping is necessary as a risk management strategy—

keeping records of inspections and maintenance activities will 

help in avoiding liability claims of insufficient signing allegedly 

contributing to vehicle crashes. 

Keeping good records will help technicians: 

 Make good decisions about when old sign panels should 

be replaced; 

 Respond more quickly to relocating or replacing signs 

frequently damaged; 

 Determine which materials are best suited for the area and 

need to effectively manage the sign program; 

 Work with law enforcement personnel to reduce 

vandalism; and 

 Defend against lawsuits arising from collision with or 

challenges about the condition of the sign. 

In addition to the sign inventory itself, there are two main 

elements of maintenance records: 

 The log or record of incident reports; and 

 The sign/sign support maintenance records. 
42 

Incident reports 

Incident reports should include: 

 The date and time the report was made or received; 

 Who made the report and who received and entered the 

report; 

 A brief description of the problem reported or observed; 

and 

 What action was taken, when it was taken and who was 

responsible for it. If there was a subsequent review of the 

work then note who made the review, when it was made 

and any subsequent actions required and taken. 

This type report could read as follows: "The STOP sign (inv. 

#3412) on the Northwest corner of the intersection of Oak St. and 

Elm St. was reported bent by a concerned citizen. The sign was 

checked and straightened by J. Smith on January 16, 2010." 

Maintenance Activity Records 

Maintenance records should be kept for any new installations, 

repairs of existing installations, or replacement jobs done on signs 

and sign supports. This will help to determine changes in your 

maintenance activities that improve driver and worker safety, 

reduce costs, and reduce potential for liability lawsuits. A sign 

(and sign support) maintenance record, report, file, or log should 

include, as a minimum, the following information: 

 Time and date of work and name of person responsible for 

completed work. 

 Sign/support location by street or highway and traffic 

direction it is facing. 

 Type of sign and size of sign if replaced. 

 Type and size of support if replaced. 
43 

 If the following were/are to be checked what were they? 

 Height to bottom of sign. 

 Color of sign. 

 Size of sign. 

 Any breakaway features of post. 

 Orientation of sign (for night traffic). 

 Wear or fading of sign. 

 Location with respect to pavement. 

 Anything blocking driver's view of sign. 

The maintenance activities records should then be used to reflect 

the changes made to the signs and/or sign supports by adjusting 

and updating the sign inventory. 
44 

REFERENCES AND OTHER SOURCES OF 

INFORMATION 

Resources available for improving the maintenance of signs and 

sign supports for local roads and streets include: 

1. Manual of Uniform Traffic Control Devices for Streets and 

Highways. Federal Highway Administration, 2009 Edition. 

Provides the standards and guidance for the size, shape, 

color, message, appropriate use and location for signs. The 

current manual is available on the Internet through the 

web site addressed: http://mutcd.fhwa.dot.gov.

2. Standard Highway Signs Handbook. Provides detailed 

drawings of signs provided in the MUTCD. Can be 

accessed at: http://mutcd.fhwa.dot.gov/sershs_millennium_eng.htm.

3. Ross, et al. ‚Recommended Procedures for the Safety 

Performance Evaluation of Highway Features,‛ NCHRP 

Report 350, Transportation Research Board, 1993. 

4. Carlson, Paul J. and Lupes, Matt S. Methods for Maintaining 

Traffic Sign Retroreflectivity, FHWA NO. FHWA-HRT-08-

026, November 2007. 

http://safety.fhwa.dot.gov/roadway_dept/night_visib/polic

y_guide/fhwahrt08026/ 

5. A Guide to Small Sign Support Hardware, 

AASHTO/AGC/ARTBA, 1988, which can be obtained at 

https://bookstore.transportation.org. Also a list of sign 

supports accepted by FHWA can be found at: 

http://safety.fhwa.dot.gov/roadway_dept/road_hardware/

signsupports.htm. (See also next reference.) 

6. Manual for Assessing Hardware. American Association of 

State Highway and Transportation Officials, 2009. 

(Available for order at 

https://bookstore.transportation.org/Item_details.aspx?id=1

539 .)
45 

7. Traffic Signing Handbook. Institute of Transportation

Engineers, 1997. 

8. Roadside Design Guide, 3rd Edition with updated Chapter 6. 

American Association of State Highway and 

Transportation Officials, January 1996. 

9. FHWA web site for Retroreflectivity and Crashworthy 

Sign Supports: http://safety.fhwa.dot.gov/. 

10. Vegetation Control for Safety, A Guide for Local Highway and 

Street Maintenance Personnel. Available at

 http://safety.fhwa.dot.gov/local_rural/training/fhwasa07018/.

 
46 

APPENDIX A: MATERIALS AND EQUIPMENT 

USED IN MAINTAINING SIGNS

Sign Posts 

For routine patrols, take several sign posts commonly used in 

your patrol area. Remember there may be several types in 

common use in the area including wood, steel U-channel, 

perforated square tube, etc. Suggested numbers of posts for large 

areas include: 

 Six (6) wood posts 4" X 4" X 12'. 

 Four (4) wood posts 4" X 6" X 14' - pre-drilled. 

 Four (4) wood posts 4" X 6" X 16' - pre-drilled. 

 Four (4) U-channel posts 8' long. 

 Four (4) U-channel posts 10' long. 

 Four (4) square steel tube posts 2.25" X 2.25" X 10’ long.

 Others as unique to your area. 

Supplies and Sign Hardware Items 

You should take enough hardware to replace a minimum of 20 

sign panels and 10 sign supports. Whenever your hardware 

supply falls below this level, obtain more before beginning a 

patrol. You will also need to carry a supply of: 

 Anti-theft, vandal-resistant fasteners. 

 Oversized neoprene or nylon washers. 

 Several boxes of bolts with nuts. 

If you plan to make field repairs to damaged sign faces (repair the 

legend or lettering) rather than do this in the shop, you will need 

additional field supplies, including: 
47 

Materials 

 Facemask to protect lungs from spray paint and dust. 

 One package of assorted capital letters. 

 One package of assorted arrows and numbers. 

 Two rolls of transparent film (one 2-inch width, one 3-inch 

width). 

 Four one-quart cans of clean sealer or equal. 

 Four one-quart cans of thinner or equal. 

 One-pint can of activator or equal. 

 One rolls each of reflective tape in red, yellow, green, 

orange, blue and white (background). 

 One container of naphtha, and a large can of wood filler. 

 Two rolls of aluminum foil tape for backing sign holes. 

 Utility knife. 

 Two rolls of masking tape. 

Hand tools 

Suggested hand tools for sign maintenance patrols: 

 Several different size adjustable wrenches and a pair of 

adjustable (horse-faced) pliers. 

 Weed cutter for clearing vegetation-blocking signs. 

 Loppers for clearing vegetation. 

 3-cu. ft. utility wheelbarrow as there may be a need to mix 

concrete for sign bases, move hole spoil, or bring in 

material to fill holes. 

 Brace and bits to drill holes in wood posts. 

 Set of woodworking chisels for trimming wood posts. 

 Hacksaw to cut bolts and rivets. 

 Crosscut saw for cutting wood posts. 

 Posthole auger, posthole digger, and posthole breaker bar 

for preparing new postholes and resetting posts. 

 Double-handed slip hammer of suitable size for driving 

posts, usually U-channel and square tube. 
48 

 16-lb. or 20-1b. double-faced sledgehammer. 

 6-lb. double-faced hammer. 

 16-oz. or 20-oz. curved claw hammer. 

 Long-handled shovel. 

 Heavy-duty tall stepladder or an extension ladder. 

 Rubber mallet. 

 Fender dolly. 

 Cold chisels, various sizes. 

Example of Truck for Sign Maintenance. 
49 

APPENDIX B: CLEAR ZONE DESCRIPTION 

The concept of clear zone is an approach to minimize the number 

and severity of crashes involving vehicles running off the road. 

Simply stated, it is a traversable area that starts at the edge of the 

traffic lane and extends laterally a sufficient distance to allow a 

driver to stop or return to the road before encountering a hazard 

or overturning. The traversable area would be considered safe, if 

there were no fixed objects, unless they are breakaway, and if the 

roadside geometry (either the fore slope, back slope, or ditch) was 

flat enough that a vehicle could safely traverse the area without 

tipping and rolling over. Roadside safety features include 

breakaway sign and light posts, and traversable drainage 

structures. Curbs are not considered a roadside safety feature 

since they can be easily mounted by errant vehicles; hence, their 

presence does not alter how clear zone is measured. 

A safe traversable slope can be either a recoverable slope or a nonrecoverable slope with a clear run-out area at the bottom. A 

recoverable slope is a slope on which a motorist may, to a greater 
50 

or lesser extent, retain or regain control of a vehicle and recover or 

stop. Slopes 1:4 (Vertical:Horizontal) or flatter are generally 

considered recoverable. A non-recoverable, traversable slope is a 

slope which is considered traversable but on which an errant 

vehicle will continue to the bottom. Embankment slopes from 1:3 

and 1:4 may be considered traversable but non-recoverable if they 

are smooth and free of fixed objects. A clear run-out area is the 

flatter area at the toe of a non-recoverable slope available for safe 

use by an errant vehicle. Slopes steeper than 1:3 are not 

considered traversable and should not be found in the clear zone. 

The objective of roadside safety is to provide and maintain as 

much clear zone as practical. The design clear zone is the 

minimum width to be provided on a project and is dependent 

upon speeds, the roadside geometry, and traffic volumes. Further 

details on clear zone can be found in the Roadside Design Guide. 
51 

APPENDIX C: THREE TYPICAL WORK ZONE 

LAYOUTS FROM MUTCD 

1. Typical Traffic Control Layout for Work Beyond the 

Shoulder 
52 

2. Typical Traffic Control Layout for Shoulder Work 

with Minor Encroachment 

3. Typical Traffic Control Layout for Mobile Operations 

on Two-Lane Road 
53