Signs help regulate traffic flow and provide valuable information to road users in order to encourage safe and efficient travel.

Key characteristics




WSDOT regions

Other names

  • signing
  • traffic control devices

Strategy description

Signs are an important and relatively low-cost method of conveying information to road users, including traffic laws, destinations, and warning of conditions that may require extra care. Great signage tends to “live in the background” of a roadway, helping road users navigate the system safely and efficiently, sometimes without them being consciously aware that they are using the signs’ guidance and warnings.

Different types of signs serve different purposes to help make roadway travel safe and efficient:

  • Regulatory signs (red, black, white) communicate right-of-way and traffic laws to maintain safety. Signs like “Stop,” “Do Not Enter,” and “No Right Turn On Red” restrict motorists from legally making certain traffic movements to help prevent collisions. Other signs, like “Speed Limit,” provide legal limitations to make roads safer and encourage efficient travel.
  • Warning signs (yellow) identify potentially dangerous conditions and sometimes provide guidance about navigating them. For example, a curve warning sign tells motorists that a curve is ahead, and the advisory speed below the sign provides a recommended safe speed for traveling around the curve. Work zone signs (orange), a subset of warning signs, are particularly important because they warn motorists of unexpected roadway conditions caused by construction or maintenance activities. Detour signs, specifically, are important to help road users efficiently navigate a work zone.
  • Guide signs (green) and destination signs (brown or blue) help drivers determine how to get where they want to be. Some guide signs help drivers choose the proper lane, and others provide the distance from their destination. Drivers rely on these signs to make trip-level decisions like when to take a break from driving to purchase gas or food. Special destination signs, like “Hospital,” can be very important during an emergency.

When to use this strategy

Signage use is governed by the Manual on Uniform Traffic Control Devices (MUTCD) and agency-specific policies. The MUTCD provides standards, guidance, and options for sign use, including instructions on when, where, and how to place signs for understanding and compliance. Agencies should also ensure each sign meets a need, because oversignage can lead to road user distraction or confusion.

Signage, as a Transportation Systems Management and Operations (TSMO) strategy, is a low cost and sustainable solution. Traffic signs are inexpensive and have a useful life of 10 years or more. When signs need to be replaced, the poles and other attachments can often be reused and the signs themselves, typically made from aluminum, are recycled.

Signs are a low-cost and quick-to-install treatment to address safety needs, especially at unsignalized intersections and at curves. Warning signs can alert drivers of upcoming issues that may require them to be especially aware of their surroundings, like roadway curvature or other road users.

Strategy benefits:

  • Signs are low-cost to install and maintain
  • Signage is a short-term solution that can be added or modified almost immediately, and often by agency staff themselves
  • Properly-placed signage conveys information to road users at the precise location it is most useful

What you need in order to implement

Planning needs:

  • Depending on the size and complexity of a signing project, planning may not be required for basic signs. For larger projects like freeway interchanges, planning and conceptual design stages are a good time to identify how signage can address road safety and efficiency while maintaining “fit “ with the signs throughout an overall corridor

Coordination needs:

  • Sign foundations require coordination with local utilities to ensure safe installation. Larger signs may require structural design

Equipment needs:

  • Depending on the size and complexity of the sign, required installation equipment ranges from basic post-hole diggers to full construction equipment and concrete bases

Maintenance needs:

  • Agencies often check signs for quality on an annual basis, and it is common for some signs to need straightening, realignment, or graffiti removal. Most signs last approximately 10 years in normal weather conditions

Agency resources needs:

  • Agencies should keep signs on-hand for near-term installation and replacement needs, especially for priority regulatory signs like “Stop” and “Do Not Enter”
  • Agencies should conduct regular sign reviews to determine sign condition and night-time retroreflectivity

Learn more about this strategy

Manual on Uniform Traffic Control Devices (MUTCD), 2009 Edition (with Revisions 1 and 2).

About key characteristics

Location notes:

Signs are important on every type of roadway.

Cost notes:

Signage is one of the most cost-effective strategies available.

Technology notes:

Static signs typically have low technology needs. Some may include flashers that require solar power or electricity.

Collaboration notes:

Agencies should coordinate with stakeholders, including property owners, at locations where new signs will be installed.