The key role of public infrastructure projects in promoting GDP growth and country development achievement as well as huge amount of investment needed for them, has multiplied the importance of effective and efficient implementation of them. Successful management and desirable value creation of these projects aligned with public interests, depends on good governance of multiple projects level which named “project portfolio”. Utilizing the principles of good governance at this level leads to portfolio performance improvement and results such as optimum projects resource allocation aligned with the organization's strategic requirements. But applying such a governance in the complex public sector, faces more barriers than private sector. Identifying and analyzing these barriers, pave the way for designing appropriate governance models. To accomplish this, 18 experts with 15 to 25 years of experience in key positions influencing on infrastructure portfolios governance were interviewed whom selected by purposeful sampling. This qualitative study is a practical-developmental research done with phenomenological methodology. Required data were collected through semi-structured interviews and then analyzed. According to findings, the barriers to road infrastructure project portfolios good governance categorized in five groups including: behavioral barriers, organizational barriers, credit barriers, macro structural barriers and macro strategic barriers drawn into a pattern of three-tier structure.