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A school bus is a bus used to transport children and adolescents to and from school and school events. Children may travel to school on regular public bus services. In some cases public bus services may run field trips and high school athletic events. Private coach services may also put on their own paid services. In North America, however, the school bus is a specific type of government regulated vehicle very distinct from other buses. Canada and the United States have specially built and equipped school buses, which by law are finished in school bus yellow, and equiped with various forms of warning and safety devices. HistoryEarly modes: wagons, kid hacksThe first school bus was horse-drawn, introduced in 1827 by George Shillibeer for a Quaker school at Abney Park in Stoke Newington, London, United Kingdom and was designed to carry 25 children.[1] Wayne Works, predecessor of Wayne Corporation, was founded in the United States of America in 1837. By 1886, and possibly earlier, it is known that the company was making horse-drawn school carriages which many people referred to as "school hacks," "school cars," "school trucks," or "kid hacks." ("hack" was a term for certain types of horse-drawn carriages.) Motorized vehicles, early school buses
In 1914, In 1927 the length of their buses to add structural rigidity and to aid in passenger protection. Known as either crash, rub, or guard rails, Wayne Works was the first known manufacturer to utilize them in bus construction. Early school buses primarily served rural areas where it was deemed impractical for the young students to walk the distances necessary to get back and forth from school on their own, and were sometimes no more than a truck with perhaps a tarpaulin stretched over the truck bed. Wayne Works was one of the earliest school bus companies to offer glass in place of the standard canvas curtains in the passenger area long before many "school" bus companies did in the early 1930s[citation needed], although it was Gillig Bros, who had invented and patented the design long before [2]. Known as the "California top", the design featured a slightly curved reinforced metal roof, with windows separated by pillars at regular intervals, and each window was adjustable by the use of a latching mechanism. Transit-style school buses
In the 1930s, Wayne Works, Crown Coach, Gillig Bros., and other school bus body companies manufactured some transit-style school buses, that is, types with a more or less flat front-end design (known in modern times as "type D" school buses). Crown Coach built the first heavy duty, high capacity, transit style school coach in 1932 and named it the "Supercoach", as many California school districts operated in terrain requiring heavy duty vehicles. Another factor in the rapid rise in transit-style school bus sales in the 1950s, especially on the West Coast, was the "Baby Boom" generation. School districts were faced with a rapid rise in student counts and were forced to consolidate, buy larger school buses, or both. As a result, the use of the transit style school bus skyrocketed during the mid 1950s. In 1959, Gillig Bros. introduced the very first rear-engine diesel-powered school bus. The C-180 Transit Coach soon afterwards became the most popular rear-engine transit-style school bus on the west coast. In 1950, Albert L. Luce, founder of the Blue Bird Body Company, developed a transit style design which evolved into the Blue Bird All-American, generally considered the first successful east coast school bus transit design. However, the "conventional" design, with a truck type hood and front-end (known as type C on modern school buses) was to continue to dominate US school bus manufacturing through the end of the 20th century. Dr. Frank W. Cyr: father of the yellow school bus
Most school buses turned the now-familiar yellow color beginning in 1939. In April of that year, Dr. Frank W. Cyr, a professor at Teachers College at Columbia University in New York organized a conference that established national school bus construction standards, including the standard color of yellow for the school bus. It became known officially as "National School Bus Chrome," later renamed "National School Bus Chrome Yellow." The color, which has come to be frequently called simply "school bus yellow", was selected because black lettering on that hue was easiest to see in the semi-darkness of early morning and late afternoon. The conference met for seven days and the attendees created a total of 45 standards, including specifications regarding body length, ceiling height, and aisle width. Dr. Cyr's conference, funded by a US $5,000 grant from the Rockefeller Foundation, was also a landmark event inasmuch as it included transportation officials from each of the then 48 states, as well as specialists from school bus manufacturing and paint companies. The conference approach to school bus safety, as well as the yellow color, has endured into the 21st century. Growth in school bus use after World War IIFollowing World War II, there were movements in Canada and the U.S. to consolidate public schools into fewer and larger ones, leading to an increase in demand for school buses. Rapid urban growth also outpaced school construction; coupled with the population expansion brought on by the baby boomers themselves having children, the need for busing within large urban centres in North America became acute.[citation needed] United States and Canada
In the United States and Canada, school buses are almost universally used to transport students. The design and operation of these buses is highly standardized and strictly regulated by federal and state laws. Many[citation needed] U.S. school districts purchase the buses and hire their own drivers, while others engage the service of school bus contractors to perform this function. This service is almost always provided without charge. StatisticsIn the United States every year, approximately 440,000 public school buses travel more than 4 billion miles and daily transport 25 million children to and from schools and school-related activities. School buses account for an estimated 10 billion student trips each year.[1] That means approximately 54% of all K–12 students in the country ride yellow school buses.[2] Protecting school children loading and unloadingBy the mid 1940's, most states had traffic laws requiring motorists to stop for school buses while children were loading or unloading.[citation needed] The justifications for this protocol were that:
Warning lights and safety devicesSchool bus safety officials were aware that many accidents occurred when traffic was not aware that the hazard existed, and children on foot were hit by other vehicles. The standardized yellow color helped and warning lettering was painted in large letters on school buses. Several devices were developed to help school bus drivers warn other motorists. Around 1946, one of the early (and possibly the first) systems of alternating traffic warning lights on school buses was used in Virginia. In those days before the advent of transistors and advanced plastic lens technology, an alternating system was created by using sealed beam headlight bulbs with the lenses colored red, and a motorized rotary switch to apply power alternately to the filaments in the single bulb fixtures mounted at the left and right of the front and rear of the bus, creating a wig-wag effect. Activation was typically through a mechanical switch attached to the door control. However, on some buses such as Gillig's Transit Coach models and the Kenworth-Pacific School Coach, activation of the roof warning lamp system was through the use of a pressure sensitive switch on a manually-controlled stop paddle lever located to the left of the driver's seat below the window. Whenever the pressure was relieved by extending the stop paddle, the electrical current was activated to the relay.[citations needed] Around this time, some states began specifying a mechanical stop arm — some state specifications, such as Washington state refer to the device as a "stop paddle", due to its resemblance to a large paddle — which the driver would swing out from the left side of the bus to warn traffic of a stop in progress. The portion of the stop arm protruding in front of traffic was initially a rectangle with "STOP" painted on it, and in the late 1960s the rectangle shape was replaced by a double-faced regulation stop sign. In later years, flashing lights were added to the stop arms, electromechanical wig-wag flasher controls were replaced by electronic ones, and the front and rear warning lights were increased from two — both red, to four — red front and rear, and eventually eight — amber to warn of an impending stop and red to indicate a stop in progress, front and rear. Some jurisdictions, such as Wisconsin and Ontario, Canada still do not permit the amber-and-red system; all-red warning systems are still used in such locales. Plastic lenses were developed in the 1950s which offered greater visibility and significantly lower costs than the early systems which used colored headlight bulbs, although manufacturers such as Gillig and Crown Coach Corporation were still using the sealed-beam glass bulb design until well into the 1980s and early 1990s.[citations needed] Protecting children from their own busA major hazard to children riding school buses is being struck by their own bus. In the United States, approximately 2/3 of students killed outside a school bus are not struck by other vehicles, but by their own bus.[3] Recently, many buses have been equipped with wire or plastic crossing arms which extend from the front bumper on the right side of the bus while it is stopped for loading/unloading. The purpose of the device is that children who need to cross the road will be forced to walk several feet forward of the front of the bus itself before they can begin to cross the road, thus ensuring that the bus driver can see them as they cross in front of the bus, avoiding a common blind spot immediately in front of the bus. School bus stop lawsSchool bus stop laws vary by locale and there is controversy[citation needed] regarding them and school bus safety. Danger zones
The area in front of a school bus has long been known[by whom?] as generally the most hazardous danger zone. An increasingly sophisticated array of mirror systems have been developed to enable school bus drivers to see children who may otherwise have been obscured from view in what was long a blind spot. Crossing arms were developed to encourage those children crossing in front of a bus to move away from the bumper area and into an area with a better view of drivers. Additionally, there has also been a trend toward bus designs with less inherent blind spots at the front. Larger windshields have also contributed to a better view forward.[citations needed] The second most dangerous zone is the area on the right side and at the right rear wheels.[citation needed] The third area of hazards are the at the loading doors. A drawstring or loose clothing may catch on something as a student gets off. If the driver isn't aware, the student may still be attached to the outside of the bus as it begins to pull away. To reduce the risk of this happening, school bus manufacturers have reduced the types of handles and equipment near the stepwell area, and children were urged to consider this risk factor when selecting clothing and accessories. Older students are at equal risk with younger ones in this regard.[citations needed] Structural integrityAs the school bus evolved in the United States and Canada as a specialized vehicle, there became concerns for the protection of the school children during major impacts. A weak point and location of structural failure in catastrophic school bus crashes was well-known to be joints, the points where panels and pieces were fastened together. Longitudinal steel guard rails had been in use since the 1930s to protect the sides of buses, but behind them on the sides and on the roofs, by the 1960s, all manufacturers were combining many individual steel panels to construct a bus body. These were usually attached by rivets or similar fasteners such as huckbolts. Around 1967, Ward Body Company of Conway, Arkansas subjected one of their school bus bodies to multiple rollovers, and noted separation at the panel joints, as well as pointing out that many of their competitors were using relatively few rivets. This resulted in new attention by all the body companies to the number and quality of fasteners. Wayne Corporation's crash tests showed the joints to be points of weakness no matter how many fasteners were used, and in 1973 the company began building "Lifeguard" buses with single longitudinal interior and exterior panels for the sides and roof. Eliminating the joints reduced the number of points for potential body separation in a catastrophic impact. The unit-panel construction reduced body weight, fastener count, and assembly time. However, it required very large roll-form presses and special equipment to handle the enormous panels. In addition, the panels had to be cut to exact length for each bus body order, which varied with the intended seating capacity and order specifications. This created a marketing disadvantage as the Wayne Lifeguard buses required greater manufacturing lead time than bus bodies made up of riveted smaller panels. 
Governmental standards for school busesThe focus on structural integrity resulted in the joint requirements of the U.S. Federal Motor Vehicle Safety Standards for school buses, most of which became applicable for school buses on April 1, 1977. The following, including Standard 221 (joint strength) are generally considered to be the most important, even thirty years later. Standard No. 217 - Bus Emergency Exits and Window Retention and Release (Effective September 1, 1973) This standard establishes minimum requirements for bus window retention and release to reduce the likelihood of passenger ejection in crashes; and for emergency exits to facilitate passenger exit in emergencies. It also requires that each school bus have an interlock system which will prevent the engine from starting if an emergency door is locked (preventing escape in an emergency) and an audible warning system which will sound an alarm if an emergency door release mechanism is not closed while the engine is running. Standard No. 220 - School Bus Rollover Protection (Effective April 1, 1977) This standard establishes performance requirements for school bus rollover protection. The purpose of this standard is to reduce the number of deaths and the severity of injuries that result from failure of the school bus body structure to withstand forces encountered in rollover crashes. Standard No. 221 - School Bus Body Joint Strength (Effective April 1, 1977) This standard establishes requirements for the strength of the body panel joints in school bus bodies. The purpose of this standard is to reduce deaths and injuries resulting from the structural collapse of school bus bodies during crashes. Standard No. 222 - School Bus Passenger Seating and Crash Protection (Effective April 1, 1977) This standard establishes occupant protection requirements for school bus passenger seating and restraining barriers. The purpose of this standard is to reduce the number of deaths and the severity of injuries that result from the impact of school bus occupants against structures within the vehicle during crashes and sudden driving maneuvers. Standard No. 301 - Fuel System Integrity - School Buses (Effective April 1, 1977) This standard specifies requirements for the integrity of motor vehicle fuel systems. Its purpose is to reduce deaths and injuries occurring from fires that may result from fuel spillage during and after motor vehicle crashes. Continuing safety efforts since 1977
The new Federal Standards of 1977 for school buses represented a quantum leap in school bus safety. Other efforts and innovations were to continue. More sophisticated and comprehensive mirror systems were developed to help drivers see children who were off the bus at almost all times. Crossing gates were developed to help children avoid walking in the area immediately in front of the bus. Reflective striping, LED and strobe lights were added in the 1980s and 1990s. Modern school buses are often well equipped with amenities lacking only a few years ago such as air conditioning, two-way radios, high headroom roofs (Gillig and Crown Coach were producing high-headroom school buses as early as the mid 1950s) and wheelchair lifts (typically those with lifts are shorter than their counterparts and are sometimes exclusively assigned to carry disabled children). Video cameras and recorders have become common equipment installed inside school buses, primarily to monitor (and record) behavior of the passengers. However, on March 28, 2000, a Murray County, Georgia, school bus was involved in a wreck with a CSX freight train at an unsignalled grade crossing, killing 3 children. Although the school bus driver claimed to have stopped and looked for approaching trains before proceeding across the tracks, the onboard camera clearly recorded that the bus had not stopped as it approached the tracks prior to the collision. Seat belts in school busesCompartmentalization was introduced in 1967, setting the ideal seat back height at 28 inches (although most seat heights are now 24 inches tall).[citation needed] The premise was that surrounding passengers with cushioning to the front and behind provide effective constraint in the event of a collision. Although not an element of compartmentalization, the UCLA researchers who conducted the 1967 tests on school buses concluded that after high back seats, next in importance to school bus passenger collision safety is the "use of a three-point belt, a lap belt or other form of effective restraint." Very few school buses have seat belts, a standard safety feature in cars and light duty passenger vehicles. In 1977, as provided in Standard 222, the federal government required passive restraint and structural integrity standards for school buses in lieu of requiring lap seat belts. In the 1980s, some districts in the US tried installing lap belts and then later removed them, claiming operational and passenger behavior problems. Whether lap belts should be required remains very controversial, although they are now required in at least 4 states (New York, New Jersey, California and Florida).[citation needed] School buses in Texas will be required to be equipped with seat belts by 2010/2011.[4] However, only one state, New Jersey, requires seat belt usage.[citation needed] In other states it is up to the district whether to use seat belts or not. Arguments against seat beltsSchool buses have an excellent safety record, and are among the safest forms of travel despite not having seat belts. School buses are heavy and move slowly; in the event of an accident, it cannot experience that same drastic change in speed and direction as smaller automobiles do (see Newton's laws of motion). Hence passengers are not thrown from their seats as easily, unlike automobiles.[5] Most fatal injuries on school buses are of other types than those preventable by seat belts.[citation needed] Compartmentalization already provides an effective constraint system, and having seat belts is seen as a redundant system. At costs of $1500 per bus to install lap belts and more for 3-point belts, the money needed to supply seat belts can be better spent in other, more protective systems.[6] Lap belts can be unsafe for young children.[citation needed] In any case, seat belts are a hindrance in cases of rapid evacuation. Children can become unable to free themselves. On buses equipped with seat belts, users typically ignore the seat belts, and in some bus routes, there are more children per seat than seat belts. In most cases 3 to 4 kids share one seat in which the heavy metal buckle can be quite uncomfortable and maybe even dangerous. Furthermore, requiring an entire school bus of forty to sixty young students to wear seat belts would be virtually impossible for a lone bus driver to enforce. Arguments for seat beltsArguments for seat belts generally come from concerned parents and teachers. The issue is on the agenda for the national PTA in Washington, although not a high priority at this time. First, studies showing the ineffectiveness of seat belts on school buses are flawed. Some believe Standard 222 was doctored by the NHTSA to meet other agendas. Others point to the use of lap belts over three-point belts, frontal crash tests over side impact tests, and the lack of rollover tests. All of these would have significantly improved the performance of seat belts versus compartmentalization.[7] Second, cost effectiveness is always a controversial issue. Some parents would argue that even saving the life of one child justifies the increased costs of installing seat belts. Diminished seating capacity can be offset by purchasing additional buses, and safety should be a higher priority than saving money. Third, three-point belt systems are promoted over lap belts, (lap belts which were criticized for causing injury to younger children). Studies have been conducted using three point belts by companies who manufacture them; these studies prove that the child's safety is greatly increased when using their product. (http://www.safeguardseat.com/)[8] As to the issue of rapid evacuation, it can be argued that children wearing the seat belts are physically unharmed to begin with and therefore should be able to get themselves out. Finally, drivers will be forced to enforce the wearing of seat belts as part of the legislation. Standards for non-school bus operativesChurch bus and school bus safety have always been closely related issues in the United States. However, they were linked more closely in the aftermath of a crash in 1988. A bus accident at Carrollton, Kentucky in 1988 involving a church bus which had been originally built and served as a school bus was one of the deadliest bus accidents in United States history. The driver and 26 other people, many of them teenagers and younger, were killed in the crash and the ensuing fire, and 34 other bus passengers sustained minor to critical injuries. Six bus passengers were not injured. It was quickly realized that many factors came together. While the immediate cause was the drunk driver of the other vehicle, it was additionally realized that most of the deaths on the bus occurred because the occupants could not evacuate promptly after the impact. The accident resulted in a National Transportation Safety Board (NTSB)[9] investigation and report, as well as extensive media coverage and considerable litigation. Subsequently, many federal, state, and local agencies and bus manufacturers changed regulations, vehicle features, and operating practices. One of the key factors in making the event was the fact that the bus was of an obsolete design which had been abandoned in school bus construction after April 1, 1977. The unprotected fuel tank was actually mounted outside the frame rails near the front of the bus. This bus was also fueled by gasoline rather than the more typical modern choice of diesel fuel. While pre-1977 buses have long been phased out of most school bus usage, many similar buses are still in use as church buses, which are far less regulated, even today. Alabama, Arkansas, Kentucky, Tennessee, and Virginia[10] are the only American states where school bus stop laws are similarly applied to church buses if equipped with flashing red lights used on school buses, and operated in compliance with school bus laws. Other states may have vehicles marked church buses, but they have no church bus stop laws similar to school bus stop laws. School bus manufacturers1980–2000: Industry consolidation, fallen flagsIn 1980, in the U.S., there were six major school bus body companies building large school buses, mostly making bodies for chassis from four truck manufacturers, joined by two coach-type school bus builders on the West Coast. With the baby boom years which swelled the ranks of school children in the past, the manufacturing industry faced serious over-capacity as companies vied and competed for lower volumes of purchases by school bus contractors, school districts, and several states which purchase their buses in quantity at the state level. On the West Coast, Crown Coach closed its doors in Chino, California in March 1991. The property buildings are completely gone, leaving an unwanted and very dirty piece of land. GE, who still does own the rights to Crown, can't sell it. Product rights and tooling were sold to Carpenter, and resulted in some Crown-by-Carpenter products in the 1990s. The other builder, Gillig Bros. (by then just simply known as the Gillig Corporation), dropped school bus production to focus on the transit bus market, and remained in business. By mid 2000, there were only three body builders left (AmTran, Blue Bird, and Thomas Built Buses), and a corporate consolidation of two of those with truck manufacturers (AmTran with Navistar in 1994, Thomas with Freightliner in 1998) reduced the model selection further. Ward had evolved into AmTran from 1980 to 1992, which would be completely absorbed into Navistar two years later. As a part of Navistar, they stopped building buses on General Motors chassis and dramatically cut back on the number of Ford chassis they bodied. Also, the International rear-engine bus chassis was only made available to other body manufacturers that sold outside the United States. (i.e., Corbeil Buses) Thomas was purchased by Freightliner in 1998. Soon after, Freightliner introduced its own bus chassis (the first new chassis maker in decades) and the Ford chassis was dropped. The International chassis (very popular among Thomas buyers) was no longer available after 2002. Several new small bus manufacturers developed niche markets during this period. However, despite several notable attempts at revival, long-term body company industry names such as Superior(1980, 1984, and 1989 under 2 failed revivals), Ward(rebranded AmTran in March 1992), Wayne(1995), Carpenter(1995, 2000), and Crown-by-Carpenter (1999) all became fallen flags (in that order). Wayne's inventory was purchased by Carpenter and some of their parts were obviously used on the Crown By Carpenter buses. A defect in the roof welds was later found on all buses manufactured between mid-1986 and 1996. A lot of school systems were forced to retire buses early and Carpenter had been out of business for sometime leaving districts no recourse. Current school bus manufacturers
Historical school bus manufacturers(all are now either defunct or have discontinued manufacturing of school buses)
Models
Diesel Electric HybridsIC Corporation, in collaboration with Enova Systems, unveiled the nation's first hybrid school bus in 2006 at the New York Association of Pupil Transportation (NYAPT) Show. The hybrid school bus is expected to attain a 40 percent increase in fuel efficiency, which becomes even more essential with the rising fuel costs affecting many school districts. Lower maintenance costs are also expected. Eleven states have joined together for an exploratory purchase of 19 school buses from IC Corporation. New York, California, Texas, Florida, Pennsylvania, Virginia, North Carolina, South Carolina, Arkansas, Iowa and Washington will be the first states in the nation to receive these diesel electric hybrid school buses. Currently, 16 of the buses are fully funded and International Truck and Engine Corporation has started production on the ordered buses for delivery in late spring 2007. School busing for racial purposesDuring the era of segregation in the United States, school buses were often used to transport Black students to all-black schools, which were often further away from their homes than other public schools designated for white students. Sometimes, these were in only one or two locations within an entire county or other school district. After the United States Supreme Court ruled in the case of Brown v. Board of Education in 1954 that school and other segregation was an unconstitutional violation of rights granted to all citizens under the Fourteenth Amendment, some districts either voluntarily or by court order introduced new pupil assignment plans to promote racial desegregation. School districts in such situations were spread across virtually the entire United States, including those of many cities such as Los Angeles, California, Boston, Massachusetts, Wichita, Kansas, Cleveland, Ohio, and Norfolk, Virginia. The desegregation plans usually resulted in more pupils of all races assigned to schools further from their homes than before. School buses (and city transit buses in some instances) were often used to transport the students reassigned to different schools beyond a reasonable walking distance. Opponents of this concept began to decry the practice as "forced busing". In cities such as Richmond, Virginia, when a massive program began in 1971, parents of all races complained about the long rides, hardships with transportation for extracurricular activities, and the separation of siblings when elementary schools at opposite sides of the city were "paired," (i.e. splitting lower and upper elementary grades into separate schools). In an effort to satisfy parents concerned about mandated long bus rides, many districts such as Richmond later modified their pupil placement plans to provide attractive programs in "magnet schools", and built new school buildings and reconfigured older buildings to develop logistically more favorable attendance plans which met desegregation goals. Combined with changes in housing patterns, the forced busing programs were gradually eliminated as the courts nationwide released districts from orders under old lawsuits. Today, school buses are still used in most of these districts, but this is much more due to reduced walking zones, concern for pupil safety, and a wider choice of programs and locations for many students. Retired school buses
When a school bus is retired from school transportation in the United States, most states have requirements that school bus lettering must be covered or removed and warning devices deactivated or removed.[citation needed] At least one state prohibits non-school buses from being more than 50% yellow, reserving the color on buses for school buses only.[citation needed] Regulations vary from state to state. Conversely, depending on state regulations, school buses may also retain their warning devices and lettering (for which usually just the "SCHOOL BUS roof lettering is allowed to remain) after retirement shall the new owner decide to restore it to factory-new condition.[citation needed] The large quantity of school buses retired from daily service has led to some being exported to Latin America for use as passenger buses, sometimes known as chicken buses. Passenger transport
Non-passenger use
MotorsportsThe school bus has commonly been used in small towns as a special class of demolition derby or figure 8 racing. Examples of speedways that prominently feature "school bus demos" include Little Valley Speedway. AustraliaIn Australia cities, students travel on regular buses and trains, or on special routes provided by ordinary bus companies. The school services cross subsidize the regular bus routes. Some smaller schools have the own buses which is an incentive for students to live near the bus routes. In country areas, contractors operate the buses. In some states such as New South Wales, travel for students for distances of 2 kilometres or more is free, costing that state about $450m per year. This makes it easy for students to choose public or private schools other than their local school. United Kingdom
Most UK school buses are ordinary buses and the only modification is the fitting of seat belts, though the ones belonging to the former Inner London Education Authority were purpose built. The buses are not necessarily yellow and can be used for other purposes when not in use for school journeys, though most children use local scheduled bus services. Dedicated school bus services in the UK in almost all cases are contracted out to local bus companies. US-style yellow school buses are beginning to be introduced, such as under the First Student UK scheme.It is also known that in Inner London many school children travel to school using the ordinary bus service as the bus stops very close together and travel is free using the Oyster card system. PollutionGenerally, a school bus is a pollution-reducing alternative to individual parents driving children to and from school, even when carpooling is taken into consideration. The use of a single school bus can take as many as fifty private cars off the road. However, buses are not a pollution-free alternative, like biking or walking. Since most school buses burn diesel, the amount of pollution emitted has been a concern for some people. Many school buses sit at idle while waiting for passengers at a pickup stop or school. Most are also sitting at idle while children are on- and off-loaded. The exposure of young children and teenagers to large amounts of diesel fumes daily for a long period of time (over ten years) has led to clean diesel requirements for new school buses in some places. However, some school district fleets include a few school buses which are over 30 years old.[citation needed] As a result, diesel electric hybrid, compressed natural gas, and hydrogen powered school buses have been developed. Some buses have been retrofitted with emission control technologies and particulate matter filters, while others are being replaced. See alsoGallery
Notes
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