Abstract
Client‑related variations such as scope changes, specification modifications, delayed instructions, and financial constraints are a major source of delays and cost overruns in infrastructure projects. Globally, they account for 6-15% of cost escalations in Europe and up to 45% of schedule slippages in Asia. In Africa, systemic challenges including weak planning and financial constraints exacerbate these impacts. In Kenya, despite recent improvements - including 4.5% sector growth reported by KNBS in 2025 and clearance of a KShs.177 billion backlog in 2026 - client‑related variations remain a key disruptor of KeNHA road projects. A descriptive research design was employed, targeting 600 respondents across 50 ongoing KeNHA projects. A total of 443 valid responses were obtained (73.8% response rate). Data was collected using structured questionnaires and analyzed through descriptive statistics, regression models, and moderation analysis. Regression analysis revealed that client‑related varwereiations explained 60.3% of the variance in project implementation outcomes, with unclear scopes, delayed instructions, and financial constraints as key drivers. Moderation analysis confirmed that project risk management significantly reduced adverse effects, raising explanatory power from 57.3% to 88.9%. Client‑related variations significantly influence project implementation outcomes in KeNHA projects, but effective risk management frameworks can mitigate their disruptive effects. Embedding proactive risk identification, clear communication, and accountability mechanisms is essential for timely, cost‑effective, and quality delivery of road infrastructure, supporting Kenya’s broader economic growth and poverty reduction objectives.