Physical ergonomics

Introduction

The term physical ergonomics typically refers to the way the design and operation of a system accounts for the physical limitations and capabilities of its users. It is focused on the way tools, environments and spaces are designed for use by people, ensuring their physical characteristics are accommodated to create a match between the person and the job, or the user and the system or equipment they are interfacing with.  Good physical ergonomic design helps enhance performance, usability and user comfort, and reduces the risk of injury, including of musculoskeletal disorder. Work that requires physical activity, interaction with systems and equipment, static or sedentary postures or tasks that are repetitive or require manipulation of heavy or unstable loads are all susceptible to risk if physical ergonomics is not considered. Awkward postures, heavy lifting, and repetitive activity are examples of workplace hazards that can result from poor ergonomic design. 

Relevance to Rail

Track work, train and maintenance vehicle operations, signalling operations (whether in a lever frame or a more modern VDU workstation) and system inspection and maintenance activities all involve people interacting with systems and performing tasks within work spaces. It is critical that rail organisations ensure that tasks and equipment are properly designed in order to maintain high network performance and a low rate of staff injury. Similarly, the rail network needs to be designed so that it can be accessed by all members of the public, whatever their size or mobility. Ensuring physical ergonomics is considered in the design of the rail environments helps keep it accessible and functioning well. For example, good physical ergonomics means handrails on trains can be easily reached by the public, that controls are placed within easy reach of a signaller, that wheelchair ramps can be swiftly accessed, assembled and then stored away by train drivers without causing injury or delaying train departure, and that technicians can lift and move equipment easily and within their lifting capacity when undertaking maintenance activities. 

Approaches and Models

Physical ergonomics applies a user-centred design approach, ensuring a connection between a user, their task, and the product or artefact used to perform that task.  Design is informed by the tasks a user will perform (typically via a task analysis), as well as the user population. User trials are typically undertaken to test a prototype of the design prior to it being finalized with a sample of people representing the typical intended users, and in scenarios aligned with intended real-world use. 

Anthropometrics is the branch of ergonomics that applies data on body measurements – size, shape, strength, mobility, flexibility and working capacity –to ensure that the design of a product, piece of equipment or work space can accommodate the physical dimensions and capabilities of its users. There are many anthropometric data sets available to designers, who can select one that best represents the targeted user population. Many rail organisations have their own data sets for their operational staff that can be used for this purpose. 

There are also a number of tools available that can support the assessment of physical ergonomic risk. Examples include workstation ergonomic assessment checklists, the Revised NIOSH Lifting Equation (for evaluating risk associated with lifting and lowering tasks), and the Assessment of Repetitive Tasks (ART) tool, which helps assess repetitive tasks involving the upper limbs.