Objective

The aim of development, build and integration phase is to develop the system’s hardware and software based on detailed designs, acquire necessary components, physically build and assemble system elements and align subsystems into an initial operational configuration to validate system-level interfaces and identify early integration risks.

Development and procurement

Description

This activity involves fabrication and coding aligned with technical specifications. Procurement decisions are guided by performance, safety, usability, and lifecycle cost considerations. The strategy must balance custom development and commercial-off-the-shelf (COTS) procurement to minimise risk and ensure compatibility with the system architecture.

Key activities

1. Design translation to build specifications. Finalise specifications for build and procurement based on verified designs.
2. Hardware and software development. Construct and code system elements, including safety and support tools.
3. Procurement execution and supplier coordination. Engage suppliers to ensure delivery aligns with integration and test schedules. Collaborate with procurement and technical teams to ensure suppliers understand all functional and usability requirements.
4. Procure off-the-shelf products. Identify and acquire COTS components that meet system performance and usability needs.

Human Factors contributions to development and procurement

Human Factors specialists play a crucial role in ensuring that design intent is maintained in development and that human-system interaction remains effective and safe.

1. Review procurement specifications. Ensure Human Factors design requirements are included in technical specifications for procured components.
2. COTS assessment. Evaluate COTS products/items for usability, compatibility, and risks of negative transfer or training implications. Use the Human Factors Risk Assessment Prompts to support consideration of introduced risks. If products were not available for testing during Detailed Design, conduct structured usability testing to compare potential products against requirements. For support in selecting metrics to utilise for the COTS assessment see the Human Factors Guidance for Evaluating Innovative Level Crossing Technologies.
3. Input to build processes. Ensure that implementation of user interfaces and control systems reflect usability standards.
4. Support for supplier engagement. Communicate human-machine interface requirements to vendors to guide customisation.

System construction

Description

Construction involves assembling hardware, loading software, and configuring systems in preparation for functional verification and integration. Construction must follow defined processes to avoid misconfiguration, with potential reliability and safety consequences. 

Key activities

1. Component assembly. Build the physical system components and subsystems.
2. Software configuration. Load and configure software.
3. Construction quality assurance. Conduct inspections and ensure all builds meet specifications.

Human Factors contributions to system construction

Human Factors specialists ensure that user-centred design elements are correctly implemented during construction.

1. Review assembled systems. Verify that controls, displays, and physical interfaces match Human Factors specifications.
2. Conduct Human Factors inspections. Participate in walk-throughs or mock-up evaluations of constructed systems.
3. Support construction quality assurance: Check construction against Human Factors-related requirements like anthropometric fit, control accessibility, and visibility.

Initial integration

Description

Initial integration involves connecting hardware and software components into a preliminary system structure. This provides an early opportunity to identify issues in data flow, control logic, and human-system interactions. Integration may include simulation or testing in controlled environments before full-scale deployment.

Key activities

1. Integration planning and setup. Define initial integration sequence, resources, and environment.
2. Interface validation. Test and debug communication across modules and subsystems.
3. Initial functional testing. Conduct baseline tests to ensure operability of critical functions.

Human Factors contributions to initial integration

This is a critical point for Human Factors specialists to identify issues that emerge from the interaction of sub-systems.

1. Participate in integration testing. Observe and assess components relevant to the human-machine interface in early system context.
2. Evaluate interface consistency. Ensure interactions between sub-systems are coherent from a user perspective and do not create issues such as user confusion or workload spikes. Use the Human Factors Risk Assessment Prompts to consider potential introduced risks.
3. Contribute to issue resolution. Advise on human-centred refinements, adjustments or the need for additional risk controls or change management processes in response to integration issues.

Next, Phase 3: Testing and acceptance