'Why do traffic signs have different shapes?' [Newbie Guide]   

Updated Sep 27, 2022 | Same topic: Beginner's Guide

These serve as visual cues depending on the urgency of the message.

One of the important things you learn in the process of earning your driver’s license is that traffic signs are meant to make driving safer on the road. That much is a given, after all. 

Traffic on the road

With so much visual stimuli on the road, traffic signs need to be immediately noticeable

But even before you take the wheel, you might already have noticed that these signs are not uniform, in the sense that they come in a variety of shapes and sizes, even colors. Are these just random products of whimsy on the part of traffic authorities, or is there a reason behind it? 

Traffic signs sport different shapes depending on the importance of the message they need to deliver, not just to the driver but for all road users. In 1915, the first official stop sign was used in Detroit, Michigan, in the U.S. The sign was small and square, with a black text against a white background. While it seemed simple and straightforward enough, it didn’t quite have the urgency needed to catch a motorist’s attention. 

Slippery when wet sign

Triangles and diamond shapes are used to caution motorists of dangers ahead

Eight years later, in 1923, highway department officials in the state of Mississippi suggested that signs use shapes to convey the level of danger ahead. The reason behind this is that our brains will interpret more complex forms as something worth paying attention to, and that belief continues to govern the use of traffic signs today. 

According to convention, the number of sides indicates the level of potential danger ahead. For instance, triangles convey instability and conflict, which makes them ideal for signs that indicate caution or danger such as an upcoming roundabout or if the road tends to be slippery under rainy conditions. 

Directional sign

Squarish and rectangular shapes are used for signs that are more informative in nature 

Four-sided shapes like squares and rectangles connote stability, so they are used in informational signs like those indicating directions. Meanwhile, a circle’s unlimited number of sides is said to represent the maximum level of danger present, which is why it’s used to warn drivers of railroad crossings or making turns with care.

Probably the only traffic sign that uses an octagonal shape is the Stop sign, which makes it recognizable even when viewed from behind.     

Stop sign

Stop signs commonly use an octagonal shape

In combination with various colors, traffic signs of different shapes are meant to elicit a different emotional response each time, which hopefully guides motorists on how to act accordingly on the road. 

Find more tips for beginner car owners at Philkotse.com.

Joseph Paolo Estabillo

Joseph Paolo Estabillo


Joseph holds a degree in Journalism from the University of the Philippines Diliman and has been writing professionally since 1999. He has written episodes for CNN Philippines' motoring show Drive, and has worked on corporate projects for MG Philippines and Pilipinas Shell. Aside from being Philkotse.com’s Content Lead, he also writes content for numerous car dealerships in the U.S., spanning multiple brands such as Alfa Romeo, Chrysler, Dodge, Jeep, and Maserati, among others.

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