Human Performance

Introduction

The term Human Performance refers to the contribution that humans make to the performance of a system. It describes how people carry out their work, whether as an individual or as a team, in order to meet a required objective.

From a HOF perspective, human performance is a key focus when considering how a system can be optimised, as well as where it can be vulnerable to failure. When systems are designed to accommodate the capabilities, limitations and skills of the people who utilise them, human performance can ensure those systems are optimized and functioning well. When they are not, human performance can be impacted, and the system becomes vulnerable. Effective systems are tolerant of variation in human performance because they have been designed to anticipate and quickly recover from impacts to human performance – and rail systems are no different. 

Relevance to Rail

The rail system relies heavily on human performance, whether it’s to operate rolling stock, to signal trains around the network, to manage network disruption, to keep stations open/ operating, to inspect/ maintain rail assets and to produce/ analyse the data that keeps timetables operational and engineering works well-planned. A high level of human performance keeps trains running to time, disruption low and rail systems performing at their best. History has shown that, as with other safety critical industries, the rail industry is vulnerable when human performance is impaired, and the consequences can be catastrophic. It is important, then, that rail organizations incorporate the need to understand and manage the impacts to human performance into their safety management systems and into their HOF programs. 

Approaches and Models

Human performance can be influenced by elements associated with a person, the tasks they are performing and the organization they belong to. These elements are typically referred to as Performance Shaping Factors (PSFs), and include fatigue, workload, situation awareness, stress, physical ergonomics and skills and knowledge. HOF programs within safety critical organizations will typically include a focus on PSFs given the impact they can have on safety and system performance. Understanding and managing the risks associated with PSFs can help reduce the likelihood of human performance being adversely impacted. 

There are numerous methods for evaluating human performance and they differ depending on the performance element being considered. Performance is often measured in terms of the volume of output, task accuracy, error rate, timeliness, presence/absence data and injury rate, to provide some examples. The key, though, is in understanding how performance was impacted, and how it can be optimized. 

For more information on some of the performance-shaping factors that can impact human performance, take a look at the more detailed topic headers under this section.