The Long Black Stripes You See On The Side Of School Buses Do More Than Just Look Weird

One of the loudest vehicles in America, visually, is the humble school bus. These mighty metal machines are tasked with carting children around safely. Thus, so much of the design of the school bus, from its eye-searing yellow color to the padded seats, serves an important safety role. One of the coolest style elements of the school bus, those long black bars along the body of the bus, also serve an important purpose. Here’s how those weird stripes help keep your kiddo safe.

The school bus is one of the simplest kinds of buses. On the surface, lots of school buses are basically just metal boxes sitting on top of a truck chassis and propelled by a reliable running gear. Look underneath, and you’ll often find leaf springs and hydraulic brakes. Lots of today’s school buses don’t even have luxuries like air-conditioning, and they can be worked on by everyday people. To put it another way, a transit bus is basically a space shuttle in comparison to a school bus.

Yet, don’t let that simplicity fool you. The school bus has been refined for longer than a century to haul lots of kids better than almost any other vehicle can. School buses are displaying their safety advancements proudly for all to see. Yet, unless you know what you’re looking for, you might not even notice. Think of the last school bus that you saw on the road. It was almost certainly yellow with black trim.

The sides of those buses have long black strips on them. You, like much of the staff of the Autopian, might wonder what those rails are there for? Are they there to protect the bus from scraping things along its side? Do they just break up the tens of feet of bright yellow?

These strips, like much of the design of the common school bus as a whole, are actually safety features that, you guessed it, are supposed to help keep kids safe. School buses themselves are amazing when you dig into their history

A Century Of Safety

Some of the earliest school buses were horse-drawn carriages in the late 19th century. These wagons were built out of wood and featured perimeter seating. These carriages were called school cars, school hacks, and kid hacks. Safety wasn’t much of a concern in those days, but in this image of a Wayne school hack, you can see that the basic shape of the school bus has been around the whole time.

As the 20th century rolled around, school hacks would eventually be replaced by motorized school buses. One of the first motor school buses was a 1914 model from the Wayne Works of Indiana. This bus featured a wood body and Ford Model T underpinnings.

The school buses of the 1910s got the job done, but wood turned out to be a poor building material. The rough, unimproved roads of the 1910s and the 1920s dealt serious blows to the wooden bus bodies. The damage to these buses was such a concern that, in 1925, Albert Luce, Sr., the founder of the Blue Bird Body Company, was concerned that his first bus wasn’t even going to last until its buyer finished paying it off.

Two years later, Luce improved his design by shoring up the wood body with steel framing. Meanwhile, in that same year, the Crown Motor Carriage Company introduced what was claimed to be America’s first school bus with dual rear wheels for a greater carrying capacity.

Perhaps the greatest school bus innovation came in 1930, when both Wayne Works and competitor Crown Coach both introduced school buses with all-metal bodies. The production of these two buses happened so closely together that some historians say that Wayne was first, while others say that Crown did it first. Either way, this was an incredible step forward in both safety and durability. These innovations didn’t stay novel for very long, either, as all-metal bus bodies became commonplace in the 1930s.

School bus advancements then took off in the 1930s. In 1932, Crown introduced a bus that had an all-steel body, a steel skeleton structure, and a chassis integrated with the body through welding. That year, Crown also introduced redundant braking systems and safety glass. Wayne would also adopt safety glass in its buses only a year later.

Another invention of the 1930s was the rub rail. While I could not find which bus builder invented the rub rail, Wayne Works is sometimes noted as a pioneer of the idea. These rails add some rigidity to the bus body, as well as add some side impact protection. However, the rub rails of the 1930s weren’t exactly the same as the rub rails that you see on school buses today, and that’s due to how widely varied school bus regulations were in the era.

Making Buses Safer In 1939

In 1939, Frank W. Cyr, a rural education specialist at Columbia University, joined forces with M. C. S. Noble, Jr. and Frederick M. Dutcher, both of Columbia University, to improve school bus safety. The men noticed that each American state had responded to technological improvements to school buses by enacting school bus regulations. The problem was that there were no true standards, so that a bus in one state could be very different than a bus in another state. From H. E. Hendrix, then President of the National Council of Chief State School Officers and State Superintendent of Public Instruction of Arizonа:

Pupil transportation, a necessary adjunct to the school system especially in rural areas, is a function created by state law and to a large extent is a state responsibility. For that reason the National Council of Chief State School Officers accepts the responsibility for setting up cooperative relations to formulate national uniform minimum standards of school bus construction, Accordingly, the conference of official representatives of the forty-eight state departments of education was convened for the purpose of formulating and agreeing upon a statement of uniform minimum standards. This publication presents the findings of that conference.

A large majority of the states by the authority of state law developed standards for school bus construction and operation which they thought were conducive to safety and economy. It now seems, however, that variations in construction standards are not resulting in economy because they hamper production of buses for a national market and compel the construction of buses as custom made jobs without materially adding to safety. It was therefore necessary that the state representatives discharge their responsibility for setting up uniform standards through cooperative action.

The National Council of Chief State School Officers is under special obligation to Frank W. Cyr and M. C. S. Noble, Jr., for giving us the benefits of their findings in the National Survey of Pupil Transportation and for organizing and conducting the conference of state representatives; and to Frederick H. Dutcher for acting as technical advisor to the conference; and to the General Education Board for the grant of funds with which to finance the conference. The full cooperation of the engineers of the automotive industry in providing technical advice is recognized. It is our hope that the standards proposed will result in greater safety and economy in school bus construction throughout the nation.

1939 was the inaugural year of the National Conference on School Bus Standards, where school representatives of the 48 states, chassis and body manufacturers, engineers, and other agencies met to create national school bus standards. Attendees included everyone from engineers from Bendix and General Motors to representatives from DuPont and U.S. Rubber.

That conference led to the creation of the “Minimum Standards for School Buses,” a manual that sought to create national safety and engineering standards for school buses. The manual set 44 standards for body length, ceiling height, standard, and aisle width. I have found the manual, and it’s fascinating. The manual describes what’s so important about setting standards:

The safe and economical transportation of nearly 4,000,000 children to and from school every day of the school year is a matter of first importance to millions of parents and thousands of school board members in all parts of the nation. In 1938, 86.099 school buses were in operation. The total number of school buses purchased from manufacturers annually is in excess of 10,000. At an estimated cost of $2,000 per bus the annual investment in school transportation facilities is about $20,000,000. These statistics indicate the extent of this important service. It is a problem of increasing importance, as indicated by the fact that from 1926 to 1938 the number of school buses increased 132%.

It would be practically impossible to make adequate consolidations of rural schools if it were not for the feasibility of pupil transportation. It is generally recognized that the need for future consolidation of schools will almost inevitably lead to expansion in pupil transportation systems.

The cost of pupil transportation may be considered as an addition to the ordinary cost of a satisfactory school program and in that sense it can be considered as a deduction from the total funds that might be available for superior school plant facilities and instructional programs. In view of this situation it is highly desirable that all possible economies consistent with pupil safetybe attained and practiced in the construction and operation of school buses.

The Minimum Standards for School Buses

I won’t list all standards, but just the most interesting ones. The manual said that the rear axle of a school bus should be a full-floating axle. A battery of at least 120 Ah was required and had to be mounted outside of the bus body. Service brakes were required to stop a bus from 20 mph to a stop in only 22 feet. Compliant buses were also required to have a hand-operated emergency brake.

The manual even set standards for fuel tanks, which had to carry at least 18 gallons, and exhaust pipes, which had to be external and dump behind the bus. There were even standards for overall length and gradeability. The manual set bus length to be no longer than 33 feet and that buses should be able to climb three percent grades at 20 mph with a full load of kids.

The safety standards were also pretty high for 1939. The bumpers were required to be rigidly mounted to the frame and were required to be able to push a vehicle of equal loaded gross weight without causing damage. The rear bumper was also required to be designed to prohibit the “hitching of rides.” Other safety standards included a required emergency door and a ceiling without protrusions that could cause injury in a crash. Buses built to the manual’s standards were even required to have first aid kits and fire extinguishers.

Many of the standards remain in use today, including the requirement that the capacity of the bus is painted on a panel inside, the requirement that buses be painted yellow with black trim, and the requirement that padded seats be permanently bolted or riveted in place. If you’re curious about what the color of school buses was back then, Frank Cyr developed a color called National School Bus Chrome. Today, the official color of a school bus is National School Bus Glossy Yellow.

Those Black Rails On School Buses

Then we get to the rub rails. In 1939, buses had only one rail, and it did not go the entire perimeter of the bus. The standard was simple, from the manual:

The body shall be protected by an applied or pressed-in rub-rail, located at the scat line of between the floor and seat lines.

In 1945, the rub-rail requirement called for two rails. This standard called for a rail at floor level and for another rail at the seat line. The 1945 manual describes why the rails were important back then:

Two rub rails of ample strength to resist impact and to prevent body crushing shall be provided on each side of the body. They shall be applied the full length of the body on the outside of the body, on the left side from the windshield post to the rear corner radius, and on the right side from the service door to the rear corner radius. One rail shall be located approximately at the seat line and the other approximately at the floor line. Pressed-in rub rails do not satisfy this requirement.

Later, rub rail standards would strengthen. The 1970 manual, for example, requires that rub rails be affixed to every body post and structural members. These rails had to be at least four inches wide, made of 16-gauge steel, and corrugated for additional strength. The 1995 manual added a third rub rail onto the side skirts of the bus body.

Today, school buses have four sets of rub rails in general. These rails will be on the side skirts, at the floor level, at the seat cushion level, and at the window level. The state of North Carolina explains further:

The rub rails of today still carry the same functions as they did in 1939: They add some reinforcement to the walls of the bus body at the safety points of the side skirts, floor, seating area, and window line.

An additional side benefit is that, in an emergency, the rub rails can be used by first responders to identify roughly where the floor and seats are. In the image below, for example, the rub rail at the floor level is actually a few inches above the floor.

Big Yellow Tanks

Modern bus regulations also require school buses to be tanks (metaphorically, that is). Here’s the standard for a modern school bus structure:

The bus body shall be constructed to withstand an intrusion force equal to the curb weight of the vehicle or 20,000 pounds, whichever is less.

Likewise, the National Highway Traffic Safety Administration has designed bus safety around the idea of compartmentalization. In the early 1970s, NHTSA discovered that school bus seats were often too weak, too low, and too “hostile” in a crash, leading to injury. As a result, NHTSA changed how it approaches school bus interior safety. From NHTSA:

Compartmentalization is directed toward ensuring that passengers are surrounded by high-backed, well-padded seats that both cushion and contain the children in a crash. If a seat is not compartmentalized by a seat back in front of it, compartmentalization must be provided by a restraining barrier. The seats and restraining barriers must be strong enough to maintain their integrity in a crash yet flexible enough to be capable of deflecting in a manner which absorbs the energy of the occupant. They must meet specified height requirements and be constructed, by use of substantial padding or other means, so that they provide protection when they are impacted by the head and legs of a passenger.

It is helpful to bear in mind the following highlights about compartmentalization:

1. Compartmentalization provides effective occupant crash protection, minimizes the hostility of the crash environment and limits the range of movement of an occupant, without using seat belts;
2. Compartmentalization ensures that high levels of crash protection are provided to each passenger independent of any action on the part of the occupant; and,
3. Seat belts are needed on passenger cars and other family vehicles and on small school buses (school buses with a GVWR of 10,000 pounds or less) because the crash pulse, or deceleration, experienced by the lighter vehicles is more severe than that of larger vehicles in similar collisions. Large school buses are inherently safer vehicles because they are larger and heavier than the vast majority of the other vehicles on the road. In addition, occupants in large school buses sit above the forces that are typically imparted to the bus by smaller impacting vehicles during a crash. The training and qualification requirements for school bus drivers and the extra care taken by other road users in their vicinity add to the safety of school buses.

The result of all of this is that school buses are surprisingly safe. On average, 108 people die each year in school bus crashes, and most of those fatalities are outside of the bus. From 2014 to 2023, there were 971 fatal school bus crashes, in which 1,079 people of all ages were killed. The American school bus fleet is roughly 480,000 units strong, and each day, some 26 million students ride to school each day on a bus.

Of course, an average of 108 deaths per year isn’t zero. Engineers, bus companies, and educators are still working to make buses safer and to reduce those fatality numbers as part of the National Congress on School Transportation.

It’s amazing how far school buses have come in over a century. In the late 1800s, a school bus was barely more than a covered wagon. Today, it’s a big, yellow beast that dutifully serves school districts for decades while safely carrying millions of students every single day. So much of it is thanks to those standards set in the 1930s, including those seemingly random black rails.

Top graphic image: Blue Bird