CSA D250-2022: School Buses Standard

Happy children boarding a CSA D250-2022 school bus.

School buses do not have seat belts and yet are 70% safer than riding in a car. In fact, the yellow school bus, which is specified in CSA D250-2022, is the safest vehicle on the road. School buses meet 42 Federal Motor Vehicle Safety Standards (FMVSS), which is more than any other vehicle on the road. Due to a detailed attention to safety, school buses account for less than 1% of traffic facilities nationwide.

The CSA D250-2022 Standard for School Buses

CSA D250-2022 functions as a manufacturing standard for school buses by specifying body equipment, chassis, and safety requirements. Bus body equipment includes aisles, bus sizes, rear bumper, color, retroreflective marking, bus sides, mirrors, undercoating, ventilation, floor covering, heating, material specifications, and the construction of the body. Chassis requirements, for instance, specify the batteries, brakes, front bumper, color, wheels, grille, hood, drive shaft, and engine exhaust system. Safety requirements include the emergency door, advanced warning devices, fire extinguisher, first aid kit, school bus identification, and alternating flashing warming lamps.

In short, there is an extensive list of bus features that CSA D250-2022 details to specify certain requirements of that feature’s location, labeling, size, strength, and/or mobility.

Developing School Bus Yellow

In 1939, the color school bus yellow (originally named National School Bus Chrome) was formulated for use on school buses in North America. In 1937, Dr. Frank W. Cyr, a professor at Teachers College, Columbia University, and also known as the “Father of the Yellow School Bus, started a study of school transportation. Cyr found that children were riding to and from school in a variety of vehicles, including trucks and buses, in all different colors.  The yellow-orange color was officially established when Cyr organized a conference that established 44 uniform national design, construction, and safety standards for school buses within America.

School bus yellow is actually considered to be neither pure yellow nor pure orange, but a mix of the two, and it is the closest to the color of a flesh of a mango. The color now known as National School Bus Glossy yellow color was selected because the black lettering on that hue was the most legible in semi-darkness in the early morning and late afternoon when children were en route to and from school. Further, scientists have found that people can see yellow objects in their peripheral field 1.24 times better than red, and, unlike red, yellow is more detectable in a dark environment and at a distance. The black lettering coupled with school bus yellow is the easiest color combination for drivers to see, and hence this color was also chosen for safety.

Defining a School Bus

CSA D250-2022 defines a school bus as a constructed vehicle that is designed to carry more than 10 persons (primarily children) to and from school or school-related events. CSA D250 applies to a variety of vehicles: Type A1, A2, B, C, and D school buses; Type A1, A2, B, C, And D accessible school buses; and multifunction school activity buses (MFSABs).

  • Type A — a conversion or body constructed upon a cutaway front section vehicle with an original equipment manufacturer chassis, supplied with a left side driver’s door. The service door is behind the front wheels.
  • Type A1 — a vehicle with a gross vehicle weight rating (GVWR) of 4581 kg (10,100 lb) or less.
  • Type A2 — a vehicle with a GVWR over 4581 kg (10,100 lb).
  • Type B — a conversion or body constructed and installed upon a van, a front section vehicle chassis, or a stripped vehicle chassis, having a GVWR of more than 4581 kg (10 100 lb). If equipped, most of the engine is beneath and/or behind the windshield and beside the driver’s seat. The service door is behind the front wheels.
  • Type C — a body installed upon a flat back cowl chassis, having a GVWR of more than 4581 kg (10,100 lb). If equipped, the entire engine is in front of the windshield, and the service door is behind the front wheels.
  • Type D — a body installed upon a chassis, having a GVWR of more than 4581 kg (10,100 lb), with the engine mounted in one of the following positions, if equipped, a) behind the windshield and beside the driver’s seat; b) at the back of the bus behind the rear wheels; or c) midship between the front and rear axles. The service door is ahead of the front axle.
  • Multifunction school activity bus (MFSAB) — a school bus designed to pick up and drop off students when there is no need for the vehicle to be equipped with traffic/ pedestrian control devices (e.g., warning lamps, stop arms).

Changes to CSA D250-2022

The first edition of CSA D250 was published in 1971, and CSA D250-2022 is the eleventh edition of the standard. When compared to the tenth edition published in 2016, the following significant changes have been made to the 2022 revision:

  • Accommodation for battery/electric vehicles and the use of non-carbon-based (e.g., hydrogen)
  • Allowance for portion of hood in direct line of vision of the driver to be school bus yellow or black
  • Allowance of stainless steel material to be used for mirror support brackets
  • Exit lamp requirements to be performance-based with requirements for the illumination of persons along the right side of the vehicle
  • Requirements for optionally installed supplemental heating systems
  • Requirement for three modes of operation for the service door so it can be controlled by the driver independent of the operation of the warning system
  • Exemption for rub rails so they are no longer required to extend over wheelchair lift doors and emergency exit doors
  • Tread surface contour for steps required to be a pebble type design
  • Allowance made for spray-on elastomer type coating for entrance steps in place of pre-formed elastomer treads

CSA D250-2022: School Buses is available on the ANSI Webstore.

Electrifying the School Bus Fleet

Presently, 1% of U.S. school buses are electric, and millions of children are riding school buses to and from school. Children who are exposed to the exhaust from diesel school buses are at an increased risk of cognitive and physical developments: asthma exacerbation, decreased lung functioning, immunologic reactions, leukemia, and infections. Electric school buses have zero tail pipe emissions, including oxide and particulate matter, and electric buses save 80% on fuel, maintenance, and repairs. There is progress toward electrifying America’s school bus fleet, as President Joe Biden’s Build Back Better plan strives to make all American-made buses zero emission by 2030. This plan would start with the school bus fleet, which would convert school buses within 5 years.

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