The risk inherent in the construction delivery has been identified as major causes of time and cost overruns in Nigeria construction industry, as such delivery and process of public infrastructure is a risky trade. Limited knowledge of the risk management techniques could result in not meeting the overall objectives of the project. The study was aimed at assessing the impediments to risk assessment techniques in Public-Private Partnership (PPP). Data for the study were gathered through the self-administration of 306 well-structured questionnaires using the simple random sampling technique to the construction professionals and private construction developers who had experience in the execution of PPP projects. Quantitative risk assessment techniques such as sensitivity analysis, scenario analysis and probability analysis percentage level of awareness were 40.1, 29.1 and 23.8 respectively, while the percentage extent of usage were 39.9, 34.0 and 37.2 respectively. In a related development, the qualitative risk assessment techniques such as probability impact table, priority table and iso-risk curves percentage level of awareness were 44.3, 38.6 and 27.5 respectively while the percentage extent of usage were 27.0, 32.8 and 26.6 respectively. Updating the knowledge base of the people responsible for the use of these risk assessment techniques by attending training and workshops in the relevant area will improve the level of awareness and the extent of usage.