What shape do highway and street work signs typically have?

Highway and street work signs are typically shaped like a diamond. This distinctive shape is used to alert drivers to unexpected conditions on the roadway, such as construction or maintenance work occurring ahead. The diamond shape is both recognizable and effective in conveying caution, as it clearly stands out against other signs. Its design is intended to capture the driver's attention and quickly communicate important information about potential hazards, helping to ensure safety for both motorists and workers. Other shapes, such as circles or triangles, are reserved for different types of messages and regulations, which is why they are not utilized for highway and street work signs.