28th International Congress on project Management "Project Management in the Digital Decade"

Accurate early-stage cost estimation in highway construction is essential for effective project planning, particularly in developing regions. However, significant discrepancies often exist between estimates provided by owners and those of contractors, largely due to limited data and differing stakeholder perspectives. This study explores how collective stakeholder insights, specifically those of owners and contractors, can improve the identification and evaluation of key cost drivers (CDs). A comprehensive list of 34 CDs was developed through literature review and expert consultation, covering technical, contractual, economic, social, and environmental aspects. These CDs were assessed using a structured questionnaire, where respondents rated each factor based on its perceived influence on overall project costs and the effort required to define it in the early phases. The survey, conducted across four Western Balkan countries, yielded 96 valid responses. Results highlight areas of both consensus and divergence between stakeholder groups, reflecting their distinct roles, responsibilities, and information access. Design-related CDs were generally seen as both high-impact and high-effort, while contractual and economic often appeared as high-impact but easier to assess. The findings underscore the value of synthesizing diverse expertise in enhancing the reliability of preliminary cost estimates and demonstrate the potential of stakeholder-informed approaches in infrastructure project management.