Friday, April 25, 2008

Human factors integration: cost and performance benefits on army systems

Paper from the US Army Research Laboratory by Harold R Booher published July 1997. Examines cost savings from human factors integration in design of army systems. The basic premise is that the solider is an integral part of the system and not an add on. Primary objectives are to assure that:

1. Adequate number of personnel with the right skills with the proper training are accounted for in the design
2. The system being designed will adequately perform the missions it is being design to do
3. The system will perform safely with a minimum potential for health hazards or soldier casualties.

Cost savings or avoidance are expected, but as a secondary objective.

Case studies

Comanche lightweight helicopter:
* Workload study showed that a one-person crew would be overloaded in critical events. Design for a two-person crew was adopted, but was justifiable.
* Task analysis was used to prioritise information to crew at specific points during missions. As an example, procedural steps required during target reporting were reduced from 34 to only 5.
* Standard rotor design met government specifications. But a new design taking into account human factors resulted in a rotor that could be maintained by less people requiring lower skill level, was less prone to maintenance error and damage during transport. Design changes required 395 man-hours (estimated cost $50,000) but lifecycle changes estimated as $150 million.
* Engine maintenance simplified. Torque wrenches not required. Connectors unique to prevent improper installations. Training burden reduced by 40%.
* Use of graphite-epoxy composite materials allows 50% of exterior skin to have access doors and panels. Identifying tasks to be performed in field allowed these to be conveniently located for access to required parts. Also, some act as work platforms eliminating the need for ladders etc.
* Projected 12,200% return on cost of human factors on the project
* Predicted that 91 soldier fatalities and 116 disabling injuries will be avoided over 20 years of use of the helicopter due to improved outside visibility, improved situational awareness, better warning of engine problems, avoidance of ground accidents during maneuvers and maintenance.

Apache Helicopter
* Original design of a control panel meant it interfered with seats during a crash and reduced how they absorbed energy and hence crew injury. Human factors analysis allowed the panel to be redesigned so that it was smaller and hence did not interfere with the seat.
* A review of maintenance practices showed that personnel habitually stood on engines, supports and hinges to gain access, which can all cause damage and injury. Support structures were redesigned to incorporate a work platform that avoided the problems.
* Analysis of maintenance task showed that unrelated components had to be removed by additional personnel to gain access. Redesign removed this problem.
* $600,000 costs for human factors give a predicted lifecycle saving of $16.8 million, which equates to a 2,8000% return.

Fox reconnaissance vehicle for nuclear, biological and chemical sample pick up and analysis
* Workload assessment showed predicted four person crew would be overloaded. Redesign of workstations allowed crew to be reduced to three
* Improved interface with sample probe reduced mission time by 12%

Overall, the case studies showed that human factors allows new technology to be used so that more benefits are achieved. Using an iterative "design," "test" and "evaluate" model allows systems to be evaluated before they are built. In one case (Fox vehicle) human factors turned the failing project from being cancelled to a success.

Andy Brazier

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