Mirroring the myriad of twists and quirks in the installation, retrofit and engagement of crossing control devices, there are even more quirks in the regulations requiring motorists approaching these vehicles to stop for them – with or without their crossing equipment engaged. As examples:

• In a few states (e.g., Alabama, Arkansas, Kentucky, Tennessee), motorists must also stop for a church bus engaging a signal (signifying loading or unloading). And in Tennessee they must also stop for youth buses. In North Carolina, motorists must stop similarly for vehicles transporting senior citizens – nomenclature that suggests how long ago such a regulation was enacted. In Ohio and Virginia, buses at which fellow motorists must stop include those transporting mental health patients, those with developmental disabilities, those transporting elderly and/or physically disabled passengers, and/or those transporting Head Start students [the transport of which, only a decade or so ago, was mandated to occur only on school buses]. In Oregon, motorists must not pass stopped "worker buses."
• In some states (e.g., Alaska, South Dakota, Utah), motorists need not stop at all for school buses with amber flashers engaged, but instead, must merely slow to a speed of no more than 20 mph. in Nebraska, this speed is 25 mph.
• In states seemingly most concerned with crossing safety – like California, which requires drivers to physically escort K–8 students across the roadway – motorists must stop for school buses with engaged flashers even on private property
• In Hawaii, a motorist must stop at least 20 feet from a school bus stopped in a residential area even if its flashers are not engaged. In Iowa and New York, this practice applies to both a private road and a driveway. In Rhode Island, the environment includes parking lots. In Ohio, this practice applies to a school bus stopped, without any flashers engaged, on any type of roadway.
• In several states (Pennsylvania, Arkansas, Virginia, Kentucky, North Carolina, Pennsylvania, Virginia), a motorist approaching a school bus must stop even if approaching it, at an intersection, from a perpendicular street— sometimes even when its flashers are not engaged.
• In a few states (e.g., Illinois, Maine, North Dakota, Tennessee, New Mexico and Texas), the school bus driver is allowed to signal fellow vehicles to proceed past it.
• Wisconsin appears so far behind available technology and NHTSA mandates that its regulations state that its red flashers must be engaged a minimum of 100 feet before the stop.
• Occasionally, passing laws are so ambiguous that it’s hard for a motorist to know what to do. In Iowa, for example, a motorist coming upon a school bus is “limited” to traveling 20 mph. Yet a driver “overtaking” a school bus may not pass it if its amber or red flashers are engaged, but instead, must stop at least 15 feet in front of it.
• Distance away from school buses at which motorists must stop when flashers are engaged appear to have no foundation, and seem almost arbitrary. This distance is 10 feet in Connecticut, Ohio, Pennsylvania and New Mexico, 15 feet in Iowa and South Dakota, 20 feet in Hawaii, Maryland, Michigan, Minnesota and Wisconsin, 25 feet in New Hampshire and New Jersey, and 30 feet in Alaska and Louisiana. Nothing noteworthy geographically, topographically or geologically in any of these states suggests anything about differences in general visibility.
• Most curious regarding distance, in Rhode Island, no motorist – with the exception of an emergency vehicle or one involving “official business” – may even travel in the same lane of traffic behind a school bus at a distance of less than 50 feet – although such a practice, while rarely articulated, is probably common to all or most states simply as a matter of safe following distance.
• In Michigan, a motorist may pass a stopped school bus with its flashers engaged at a speed of no more than 10 mph. In New Jersey, a motorist may pass a school bus with its flashers engaged anywhere at no more than 10 mph.
• In New Jersey – my birthplace and favorite deviant – “frozen desert trucks” may employ red flashers, yet motorists may pass them at a speed no greater than 15 mph.
• Some exceptions apparently “still on the books” appear to have been enacted during the electronic age. For example, in West Virginia, motorists must stop when the school bus driver either engages the vehicle’s flashers or is standing alongside it waving a red caution flag

The effort to even collect this level of information must have been a bear, and some of these observations may not even be accurate, while others are, by now, likely obsolete. Otherwise, someone looking for a pattern in this maze of quirks and exceptions – such as climate, density, topography, ethnicity, culture or even approaches toward comparative negligence –– will die of old age long before finding one.

The one exception to this rule – a pattern that appears to apply almost universally (with the exceptions of New Jersey and Michigan) – is that a motorist cannot pass a school bus with its red flashers engaged. Yet comparing the list above with the observations in Part 3A of this series, which examines only rules about amber lights, suggests that what uniformity as may have existed 30 years ago when only red flashers were required as a Federal matter began to break down when amber lights were mandated, particularly as this mandate was not accompanied by a parallel mandate for retrofitting (which only a handful of states, like Missouri, require).

Finally, little data appears to be available regarding the school bus’ position when stopped. In many states, school buses must pull off the road. In Oregon, they are not allowed to, but instead, must stop in the travel lane. In Arizona, they may do either (and from my own forensic experiences, pulling only partway off the roadway is not acceptable, as it invites rear–ending).