A Brief Guide to U.S. Traffic Signs

Did you know that primitive road signs date back as early as the Roman Empire? It’s true.

Not surprisingly, the city of Rome was the cultural center of this vast empire, and all roads were considered to begin there. As such, the conquerors began erecting stone columns with the distance to Rome carved into them. The earliest of these stone markers — called milestones — were carved from locally available rock and often weighed in excess of 4,000 pounds. Each stone gave the distance to the Milliarium Aureum, or Golden Milestone, which used to be located in the central Forum of Rome. This system of measurement was so prevalent that it would later lead to the common adage that “All roads lead to Rome.”

Through the years, road signs evolved to provide travelers with information regarding both the distance to and the direction of various towns, not just Rome. It wasn’t until the emergence of early bicycles in the late 19th century, however, that warning signs started to emerge. These machines were very quiet, fast, and difficult to control. As their use grew, various cycling organizations began erecting signs that would warn cyclists of potential dangers, especially the presence of steep inclines ahead.

The evolution of road signs into our modern system of traffic signs started with the invention of the automobile. More complex signage was needed in order to direct the ever increasing number of drivers on the roads, and early attempts at nationwide standardization of road signs in the United States started in the 1920s.

Modern U.S. Traffic Signs

U.S. Traffic Sign Regulation and Standardization

Today, traffic signs in the United States have a pretty uniform feel to them. If you’ve ever traveled to a different state, you’ve probably noticed that the signs, signals, and road surface markings are pretty similar to the ones in your hometown. That’s because they follow the standards set forth in the Manual on Uniform Traffic Control Devices (MUTCD) created by the Federal Highway Administration (FHWA) of the United States Department of Transportation (USDOT). The federal MUTCD provides set standards for the design, installation, and use of traffic signals, signs, and road surface markings throughout the United States. In fact, all traffic control devices in the country are supposed to conform to the standards contained in the MUTCD.

These standards include specific instructions on the shapes, colors, and fonts that are to be used in road signs and markings, and are used by various groups including:

●     State Transportation Agencies

●     Local Transportation Agencies

●     Private Construction Firms

There are, however, some state agencies that have chosen to develop their own sets of standards and/or MUTCDs, but those local standards should technically conform to the federal MUTCD.

Common U.S. Traffic Signs

Most traffic signs in the United States fall into one of six categories.

1. Regulatory Signs (R Series) - Regulatory signs are designed to provide instructions to drivers, pedestrians and cyclists. Some of these signs, like rail road crossings and stop signs, have specific shapes or colors that must be adhered to. Some common signs that fall under regulatory signs are:

●     Stop Signs

●     Yield Signs

●     Speed Limit Signs

●     Turn and Lane Usage Signs

●     Do Not Enter Signs

●     One Way Signs

●     Parking Regulation Signs

●     Road Closed Signs

●     Weight Limit Signs

●     Railway Signs

2. School Signs (S Series) - S series signs refer to the types of signs used to regulate traffic around schools. Under the current MUTCD, warning signs used around schools are supposed to feature a fluorescent yellow-green background to set them apart from the standard yellow used in most warning signs.

3. Warning Signs (W Series) - Almost all traffic signs in the W series utilize a yellow background and are used to warn of existing road conditions and possible dangers. Some states utilize the same fluorescent background found in school signs for any sign dealing with pedestrians. Orange warning signs are typically used over relatively short periods of time to warn of temporary conditions like those existing in construction zones. Some common warning signs include:

●     Turn and Curve Warning Signs

●     Intersection Warning Signs

●     Advance Traffic Control Signs

●     Lane Merge Signs

●     Divided Highway Signs

●     Hill and Grade Warning Signs

●     Pavement Condition Warning Signs

●     Railway Warning Signs

●     Low Clearance Signs

●     Speed Advisory Signs

●     Work Zone and Road Work Signs

●     Temporary Lane Shift Signs

4. Guide Signs - Guide signs, as their name implies, are used to guide people toward their destinations. They include:

●     Mile Markers

●     Highway Route Markers (Shields)

●     Exit Signs

●     Street Signs

●     Some Toll Road Signs

●     Local Services Signs

●     Rest Area Signs

5. Toll Road Signs - While some toll road signs are covered under guide signs, one section of the MUTCD deals specifically with toll road signs.

6. Hospital Signs - Blue hospital and trauma center signs are also regulated under the MUTCD.

Of course, there are so many different traffic signs that we could not possibly cover them all here. As you travel to your next destination, you should take a moment to consider just how many signs, signals, and road markings are present along your route to help safely guide you to your destination.