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The United States is known the world over for its bright yellow school buses with black trim. From movies to TV shows, the yellow school bus has become a symbol of American education and childhood. While the color of a school bus is the first thing that jumps out at us and causes many to wonder why school buses are yellow, their black lines get a fair amount of attention too. That’s because the black lines on a bus are hard to miss and are an integral part of the design. Along with the yellow color, they give school buses a distinct look that makes them immediately recognizable at a distance.

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This is important because, as many of us learned in driver’s ed, there are special rules we must follow when a school bus is nearby. For example, when a school bus flashes its red lights and extends its stop sign, traffic must stop in both directions to allow children to get on and off the bus safely. As it turns out, the black lines on school buses aren’t just decoration; they play an important role in providing structural support to the vehicle. While there are no laws at the federal level that require school districts to include these black lines on their buses, many states, such as New Jersey and Pennsylvania, have regulations governing their use.

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The black lines you see on school buses are called rub rails, and despite what many may think, they aren’t there just for looks — they have an important safety function. Just like modern cars come equipped with a variety of safety features to protect passengers, school buses do, too. Rub rails are typically made of 16-gauge steel or similarly durable materials, which are often outlined in a state regulations. 

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They’re used to reinforce a bus’s thin sheet metal, adding an extra layer of strength and protection to the vehicle. If the bus is involved in a collision, the rub rails will help absorb and distribute its impact, as opposed to a car hitting a large, flat metal panel (absent rub rails) and potentially causing extensive damage to the bus.

The rub rails’ black color, along with the black lettering on school buses, helps increase the vehicle’s visibility. The black stripes create a sharp contrast when paired with the bright yellow of a school bus, making it easier for other drivers to spot. When drivers see those colors, they are more likely to pay attention and get ready to stop.

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There’s no federal law that mandates rub rails on school buses. The National Highway Traffic Safety Administration (NHTSA) oversees school bus safety regulations, but there’s no federal law that specifically requires school districts to equip their buses with rub rails. While there are no federal rules mandating the use of rub rails on school buses, and regulations vary from state to state, the National Congress on School Transportation (NCST) has adopted guidelines that cover different aspects of school bus design and operation, including the use of rub rails. 

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The NCST typically meets every five years but didn’t meet in 2020 due to the COVID-19 pandemic. Thus, the latest guidance available is from 2015, where the Congress laid out its recommendations for rub rails on school buses. These regulations cover everything from the type of material that should be used to make rub rails — 16-gauge metal or other material of equivalent strength — to their placement. 

This guidance is solely recommendatory and not legally binding. However, many states have adopted these recommendations and incorporated them into their own regulations. Because rub rails are regulated at the state level, their implementation varies from one location to the next. However, almost all school buses include rub rails as a standard safety feature.

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When shopping for a new vehicle, safety-conscious consumers often look at car brands with the best safety ratings. While you won’t find these types of ratings for school buses, they are designed with safety in mind. Rub rails are one of the most important safety features on a school bus and are strategically placed to reinforce its structural integrity. Since the NHTSA hasn’t established any rules on the placement of rub rails, many states follow the NCST’s guidance when determining where to put them.

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According to NCST guidance, school buses should have at least two rub rails. There should be one rub rail no more than eight inches above the seat cushion level that runs along the sides of the bus. Another rub rail should be placed on each side of the bus no more than 10 inches above the floor line. The rub rails should be attached at structural points and made of 16-gauge metal or the equivalent. While these guidelines aren’t legally binding, and some states require more than two rub rails, they serve as a baseline for many state regulations.

For example, Arizona requires at least two rub rails, with one placed at seat cushion level that runs from the service door to the back of the bus. In contrast, Pennsylvania mandates three rub rails with one at the seat level, another at the floor line, and the final as low as possible on the lower body panel. As you can see from these examples, rub rail requirements vary by state, with each establishing its own standards for placement and design.

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A quick search for “what are the black lines on a school bus for?” will yield many results, but unfortunately, a lot of them are inaccurate. That’s because a few years back a video went viral saying that the rub rails on a school bus mark the locations of the floor and seats to help emergency responders during a crash. The video in question racked up almost 4 million views and was picked up by various media outlets and reported as fact. In reality, there’s no evidence to suggest that the placement of the black lines on school buses has anything to do with guiding first responders during rescue operations. 

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That being said, it’s possible emergency personnel are trained to use these lines as visual cues when responding to an accident involving a school bus. However, it’s important to note that this is not the primary reason for their placement and they weren’t designed for this purpose. Instead, the real purpose of rub rails is to reinforce the bus’s structure. A representative from Blue Bird, a major American school bus manufacturer, told Snopes, “At Blue Bird, the intended design of a rub rail is actually part of the structural integrity of a school bus. They are there so that buses can meet crash test and other safety requirements. Not all rub rails are black — sometimes they are yellow like the bus, or another color!”

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An article in FIREFighting in Canada also seeks to debunk the emergency responder myth, saying, “It’s unclear why the idea was hatched to aid extrication in the first place, but in the end, it’s (mostly) a myth.” What it comes down to is that while the black lines on school buses may generally align with the floor, seats, and interior spaces, this is purely coincidental and not an intentional part of the design.