School buses come in a variety of colors, but the most iconic and common color for school buses in the United States and Canada is “National School Bus Glossy Yellow.” This specific color was standardized in 1939 and has been used on school buses for over 80 years. The purpose of having a uniform and distinct school bus yellow color is for visibility and safety – to make the buses stand out from other vehicles and be easily recognized. But what exactly is this official school bus yellow color? Let’s take a closer look at the history, specifications, and variations of this familiar shade.
History of Standardized School Bus Yellow
In 1939, a conference sponsored by the Columbia University Teachers College established National School Bus Chrome (also referred to as National School Bus Glossy Yellow) as the standard paint color for all school buses in the United States. Before this standardization, school buses came in a variety of colors including red, blue, green, and black. The conference recommended National School Bus Chrome for its high visibility and ability to reflect light, improving safety. This color specification has been maintained by SBMTC (School Bus Manufacturers Technical Council) and NASDPTS (National Association of State Directors of Pupil Transportation Services) since 1939.
Some key events in the history of standardized school bus yellow:
– 1914: The first mass-produced school bus was introduced by Wayne Works, painted Orange-Yellow.
– 1939: National School Bus Chrome yellow was standardized at the Columbia University conference.
– 1976: Federal Motor Vehicle Safety Standard (FMVSS) 108 was implemented, requiring reflective NSBY yellow for school buses.
– 2022: Most recent testing and specification update for NSBY was adopted by NASDPTS.
So for over 80 years, school buses across North America have been painted a specific shade of yellow for maximum visibility. While the exact formulation has been updated, the color has remained remarkably consistent.
Specifications
The official specifications for National School Bus Glossy Yellow are defined by standards organizations. Here are the technical details:
| Standards Body | Specification |
| NASDPTS | EEC-2138 |
| ASTM International | ASTM D6335-16 |
| CIE Lab Color Space | L*: 83.14 a*: 14.36 b*: 67.46 |
This defines the exact formulation for school bus yellow paint in terms of chromaticity values, lightness, brightness, hue, and saturation. The ASTM and CIE Lab standards provide the technical measurements to reproduce the color accurately.
These specifications are periodically updated. The latest revision was approved by NASDPTS in 2022. They ensure that new school buses use the same consistent yellow as older models for uniformity. Any paint branded as “National School Bus Glossy Yellow” should meet these color standards.
Variations
While there is an official standard, in reality there can be slight variations in NSBY shades between bus manufacturers or over time.
Some factors that can affect school bus yellow hue and brightness:
– Manufacturing process – The mixing and spraying of paint may produce slight variances.
– Paint batch – Different batches mixed at different times may have slight color deviations.
– Fading – Exposure to sunlight and weathering over years of service can fade the original vibrancy of the paint.
– Lighting – The bus will appear slightly different colors under sunlight, shade, or artificial light.
– Age – As mentioned above, older school bus paint eventually becomes duller and less reflective.
– Conditions – Dirt, oxidation, and grime buildup will also affect the actual appearance of the buses yellow over time.
So you may notice slight variations in National School Bus Yellow, even when they are painted from the same specification. Adjacent buses may look slightly different. But the color is engineered to fall within an acceptable range around the CIE chromaticity standard. It is recognizable as “school bus yellow” anywhere in North America.
Conclusion
While school buses may come in many colors around the world, National School Bus Glossy Yellow (NSBY) has been the standard color for North American school buses since 1939. This distinctive shade provides visibility and safety. The exact specifications have been maintained and updated by industry organizations like NASDPTS and use color standards like ASTM and CIE Lab. There can be slight variations between bus paint jobs in reality, but the color is formulated to be clearly recognizable as the iconic school bus yellow. So next time you see a school bus, you’ll know it is painted in a very specific color defined by chromaticity, lightness, hue, and other measurements – a color engineered to keep kids safe.
