Vehicle False Park Expert Article

A ‘false park’ incident can result in unintended vehicle movement after attempting or intending to put a vehicle in Park. False park is a widely recognized hazard throughout the automotive industry, frequently associated with injuries or fatalities when the unintended movement results in the vehicle striking a pedestrian (which often times was the driver prior to parking).

In this article, Automotive Engineer and Crash Expert Steven Becker discusses the factors that contribute to unintended vehicle movement, safety features currently available in passenger vehicles that can prevent false park incidents, and the standard of care for safe vehicle design.

Vehicle False Park - Expert Article

What happens when a vehicle is placed in park?

When the shift select system is placed in Park, a vehicle should be immobilized, safeguarding persons and property from the dangerous forces of a moving, likely driverless, vehicle. Shifting to Park initiates three primary processes to restrain the vehicle.

1. The transmission shifts to neutral, isolating engine forces from the drivetrain (axles and tires),
2. A parking pawl engages within the transmission to prevent movement of the drivetrain.
3. An electronic parking brake is automatically applied, in vehicles so equipped.

The combination of these processes is effective at immobilizing vehicles under normal and expected operating conditions. Unintended movement of a parked vehicle requires either a failure of a vehicle system, user error, or some combination of the two.

Case Example

In this vehicle/pedestrian collision, the plaintiff parked to pick-up a food order, intended to put the vehicle in park, left the engine running, and exited his vehicle. Shortly thereafter the plaintiff’s adolescent son, in the passenger seat, recognized that the vehicle was moving in reverse and exited the vehicle to try and stop it. In doing so, the son’s leg was crushed between the vehicle and a bollard.

Robson Forensic was retained to determine if there was a defect in the vehicle that caused the collision.

Details

• This vehicle was equipped with an automatic transmission that was completely controlled, even the application of the Park pawl, electronically. There was no mechanical connection between the shift selector and the transmission.
  
• The driver intended to put the vehicle in Park.
• The car did not move while he was exiting the vehicle or during the time he was walking through the parking lot.
• The manufacturer had been notified by NHTSA months earlier that there was a potential defect associated with their monostable shifter and unintended vehicle movement, but no recalls had been issued at the time of the crash.
• The solution that was later issued for the recall was to alter the transmission software to automatically apply the Park gear shift position when the door is opened while the vehicle is stopped (if Park has not already been engaged). Similar safeguards have been used throughout the automotive industry to guard against unattended/unintended vehicle movement since the advent of automatic transmissions with full electronic control.

Expert Findings

Feasible and economically viable alternative solutions to prevent unattended/unintended movement were available at the time the manufacturer designed its automatic transmission gear position select system for this vehicle. The manufacturer failed to properly apply the design safety hierarchy and designed the automatic transmission gear position select system in this model without equipping such a solution. This occurred even though other manufactures using this same brand and model of transmission installed this guard in their vehicles.

As the plaintiff thought he had applied the shift selector into Park, when actually the selector was in Reverse, and based on the lack of positional feedback from the shift selector and/or an electronic safety guard, our investigation determined that the plaintiff’s vehicle was defective in a manner that caused the collision.

Standard of Care for Auto Manufacturers

The ability to keep a vehicle stopped is among the most important safety requirements in automotive design. It is essential that the gear selector functions as expected and initiates the corresponding processes to immobilize the vehicle. Absent these safeguards, an uncontrolled vehicle moving while powered, or in neutral, becomes a dangerous condition that can cause serious damage and rollover/crush fatalities.

The standard of care is that manufacturers of products address known hazards and evaluate safer designs. Evaluation of safer designs takes into account many factors, most importantly safety, but also including:

• Technological feasibility, including the availability of the technology.
• Economic feasibility, including the cost of the alternative design.
• Impact on the operation of the vehicle.
• Potential adverse impacts of any alternative design on any of these factors.

Vehicles must be designed and manufactured in a manner that prevents ambiguity in the operation of critical safety systems. In product design, there are basic and fundamental steps that must be considered by a designer and/or manufacturer before selecting a design. The process is referred to as a Hazards Analysis, and after identifying each hazard will either:

• Design out the hazard
• Isolate or guard the hazard
• Warn of the hazard

The highest priority applies to designing out the hazard. If the hazard cannot be designed out, then the next priority is to isolate or guard users from the hazard, and lastly to warn against the hazard.

If there are practical design alternatives that would eliminate or reduce the danger, then that condition of danger is unacceptable and the design is defective. A proper hazards analysis would acknowledge the failure mode of an unattended unintended vehicle movement and identify its causes.

Applying the Hierarchy of Hazard Analysis to the known hazard of unattended or unintended vehicle movement, it is impractical to design out the hazard of vehicle movement; immobilizing the vehicle would eliminate its intended purpose. Instead, product designers can isolate vehicle passengers from unintended vehicle movement by way of electronic safeguarding that prevents vehicle movement under specific criteria with elevated risk of harm.

Electronic Safety Systems

Modern vehicles can be designed with electronic safety systems to prevent a driver from exiting a vehicle before it is safely in Park. This can include systems that automatically set the vehicle to Park if the driver’s seatbelt is unlatched and the driver’s side door opens while the vehicle is in another gear, or having a warning sound go off under these same conditions to alert the driver. Vehicles, like the one in our case example, that are equipped with electronically controlled parking brakes can also be programmed to engage the parking brake if these circumstances are seen by the vehicle’s control units. Either of these systems can guard against the hazard of an unintended vehicle in motion.

Expert Witness Investigations Involving False Park Incidents

The vehicle experts at Robson Forensic are more than just mechanical engineers and reconstructionists, they are automotive engineers with industry experience in design, development, and manufacturing. Our experts have designed, fine-tuned, and incorporated driver aids and semi-autonomous systems into modern passenger vehicles.

For more information, call us at 800.813.6736 or submit an inquiry.

Featured Expert

Steven Becker

Automotive Engineer & Crash Expert

Steven is a vehicle engineer with more than thirty years of experience and has worked directly for automotive manufacturers and tier 1 automotive parts suppliers. He provides investigations, reports,… read more.