Passive structures and active systems instill safe transport

EDITOR’ NOTE: This material was drawn from a presentation by ABC Companies, Winter Garden, FL, as part of its annual Collision Conference.

In light of current events casting a long negative shadow over the motorcoach industry, operators may be facing situations that require their very specific explanations for the claim that their vehicles are the safest mode of transportation on the highway.

While the government agencies and Congress continue weighs in on whether more must be done to make motorcoaches more structurally sound, the existing engineering and construction make a strong argument for regard to safety.

Though the engineering always begins with the federally regulated safety requirements, in most modern motorcoaches the extra safety considerations continue to surpass the minimum standards.

To overcome any negativity, a coach owner might do well to explain the dominant passive and active systems intentionally built in that contribute to a safe ride.

Passive safety systems

Passive systems are the safety functions OEMs incorporate into the design of the vehicle to enhance safe operation and to protect the passengers. There is usually nothing an operator needs to do to engage a passive system and take advantage of its inherent safety aspects.

Compartmentalization — With the current focus on seatbelts, it is important for the public to understand the special role energy absorbing seat structures play in protecting passengers against unexpected directional or speed changes. The containment function is analogous to eggs surrounded and protected in their small compartments of an egg carton.

Elevated cabin — The floor height of the average luxury motorcoach is approximately two inches higher than the hood of the average pickup truck. Passengers ride above most traffic removed from harm’s way and protected from the direct impact of vehicles approaching from the side. The baggage compartment structure beneath the cabin absorbs much of the impact energy from a colliding vehicle, benefitting the occupants of both vehicles.

Window glass and frames — Tempered and laminated window glass both incorporate unique safety features. Passengers can shatter tempered glass to create an opening with few jagged edges, while laminated glass retains some containment capabilities when it breaks.

Laminated glass mounted in swing out frames allows egress in some applications. Windshields and some side glass are made of laminated glass yet only some side glass actually swings out. Regulations do not require all side windows to be emergency egress paths so a vehicle may have a mix of fixed laminated and swing out laminated on the sides.

Emergency exit markings. Color-coded markings for front entrance doors; side entrance doors on some vehicles, roof hatches, stairwells and windows indicate the egress paths in case of an emergency. Similar to the airlines, explaining these features before starting any trip alerts passengers to the exit plan, and sends a signal that the operator is safety conscious.

Failsafe mechanisms — It is necessary for certain systems to function manually in the event of a power failure. For example, if the coach loses electrical power the air-powered latches release and allow the front entrance door to drop down free of the latches and open by hand.

Accessibility — Easy access to functional and structural components and routine maintenance items promote safety. Doors and panels that open easy to reach placements make it easier for technicians to inspect critical equipment and parts for inspection, maintenance and repair.

Active safety systems

Active systems engage either automatically or require the operator to act to initiate a designed sequence of events in an emergency situation.

Antilock brakes — ABS monitors the speed of each wheel and can determine if lock up occurs during braking. A locked up or skidding wheel cannot be steered, ABS modulates or pumps the brake at the point of lock up and restores control. It is important to note that ABS increases control at the expense of increased braking distances.

Automatic traction control — ATC, like ABS, also monitors wheel speed and detects wheel spin. ATC reduces wheel spin by also modulating the brakes, restoring traction and control on slippery road surfaces.

Electronic stability control — ESC automatically and selectively brakes individual wheels to control over-steering and under-steering to keep the vehicle within its performance envelope. This is particularly advantageous on curves and during transitional maneuvers.

Vehicle health monitors — Tire pressure monitors alert the driver of abnormal pressures and temperatures. The advance warning allows the driver more time to take corrective action.

Engine and transmission performance alerts warn the driver of operational exceptions such as excessive engine temperature or high exhaust backpressure. The situation may require a corrective action such as power reduction or a regenerative cycle.

Predictive maintenance systems — Monitors that detect wear of components such as clutch or oil are able to advise technicians of the remaining service life, which minimizes downtime due to unscheduled repairs.

Fire suppression — Fire suppressors and extinguishers detect the presence of flame or excessive heat in engine compartment, releases a nontoxic, dry powder extinguishing agent on the fire or flash front within the blink of an eye and maintains a non-sustaining environment for 15 to 30 seconds. A fire suppression system alerts the driver of a critical event, allowing time to bring the vehicle to a safe stop as the retardant discharges. Most suppression systems shut the engine down to reduce the risk of re-ignition unless the driver overrides the shutdown for an additional 15 to 30 seconds of drive time.

OEM operator support — OEM service and communication play an active roll in accident prevention. Regional service facilities and OEM training events provide operators with the ability to assure proper maintenance and vehicle upkeep. Ongoing industry events and maintenance seminars relate directly to safety, where, in addition to the many mechanical and engineering aspects, the topics also take into account coach operator compliance issues and driver safety training monitoring.