[Paper Review] Agile Islands in a Waterfall Environment: Requirements Engineering Challenges and Strategies in Automotive

Rashidah Kasauli, Eric Knauss+2 more|arXiv (Cornell University)|Jun 21, 2021

Software Engineering Techniques and Practices40 references15 citations

TL;DR

This paper investigates requirements engineering (RE) challenges in automotive companies where agile software teams operate within a plan-driven (waterfall) systems engineering environment. Through a multi-case study with 18 interviews and one focus group, it identifies key RE challenges—such as poor traceability, lack of visibility into high-level requirements, and inconsistent requirement updates—and proposes strategies like cross-functional teams, improved tooling, and role clarity to mitigate them, highlighting the need for more empirical research on hybrid RE practices in large-scale systems.

ABSTRACT

[Context & motivation] Driven by the need for faster time-to-market and reduced development lead-time, large-scale systems engineering companies are adopting agile methods in their organizations. This agile transformation is challenging and it is common that adoption starts bottom-up with agile software teams within the context of traditional company structures. [Question/Problem] This creates the challenge of agile teams working within a document-centric and plan-driven (or waterfall) environment. While it may be desirable to take the best of both worlds, it is not clear how that can be achieved especially with respect to managing requirements in large-scale systems. [Principal ideas/Results] This paper presents an exploratory case study at an automotive company, focusing on two departments of a large-scale systems company that is in the process of company-wide agile adoption. [Contribution] We present challenges related to requirements engineering that agile teams face while working within a larger plan-driven context and propose potential strategies to mitigate the challenges. Challenges relate to, e.g., development teams not being aware of the high-level requirement and dealing with flexibility of writing user stories. We found that strategies for overcoming most of these challenges are still lacking and thus call for more research.

Motivation & Objective

• Investigate the challenges faced by agile software teams working within a plan-driven, document-centric automotive systems engineering environment.
• Understand how requirements flow and are managed when agile development coexists with traditional systems engineering practices.
• Identify and analyze mitigation strategies for requirements engineering issues arising from the coexistence of agile and plan-driven methodologies.
• Provide empirical insights from developers' perspectives on RE in hybrid development environments, especially in the context of large-scale automotive systems.
• Highlight the gap in existing research on developer-level experiences with RE in agile-island scenarios and call for further empirical investigation.

Proposed method

• Conducted an exploratory case study in two departments of a large-scale automotive systems engineering company.
• Collected data through 18 individual interviews and one focus group with developers, testers, and requirements engineers.
• Analyzed challenges and mitigation strategies related to requirements engineering using thematic analysis of interview transcripts.
• Mapped identified challenges to existing literature on agile and plan-driven coexistence, particularly focusing on traceability, requirement ownership, and system-level visibility.
• Proposed practical strategies based on interviewees' experiences, such as integrating testers into agile teams and improving role clarity.
• Used a comparative approach to contrast practices and challenges between two departments with different levels of agile maturity and autonomy.

Experimental results

Research questions

• RQ1 RQ1: What are the perceived challenges related to requirements engineering when combining plan-driven and agile paradigms in large-scale systems engineering?
• RQ2 RQ2: What mitigation strategies exist when using agile development in a traditional, plan-driven setting?
• RQ3 RQ3: How do differences in organizational structure and team autonomy influence the severity and nature of RE challenges in agile-island contexts?

Key findings

• Agile teams in Department A often remained unaware of high-level system requirements, leading to misalignment with overall system goals.
• Inconsistent traceability between user stories and the formal requirements model resulted in duplicated testing and rework, especially when requirements were not updated after changes.
• Many new user stories emerged during implementation without corresponding formal requirement updates, exacerbating traceability issues.
• Department B experienced fewer inconsistencies due to stricter user story management and better-defined roles, though system-level visibility remained a challenge.
• The lack of a complete system picture led to poor system thinking, as teams focused on features without understanding interdependencies between subsystems.
• Proposed solutions such as cross-functional teams and visualizing functional relationships were seen as effective but required cultural and process changes to implement successfully.