Despite of extensive and systematic usage of ‘Lag’ type of performance metrics, Large Infrastructure Projects (LIPs) often struggle in achieving the intended performance and frequently tend to be overbudget & delivered late. This research investigates Key ‘Lead’ Indicators (KLIs) and provides suggestions on how to measure and influence them in the future large rail infrastructure projects. These ‘Lead’ Indicators are forward-looking performance metrics, unlike the ‘Lag’ indicators, and can forecast the deviation in the project performance at an early stage. Building on existing insights from theory on lead indicators, it asks: How can Key Lead Indicators be used to improve project performance of inner-city rail infrastructure projects across Europe? The research is performed through a combination of mixed qualitative research methods including literature review, case studies and an expert consultation meeting. From the literature review, it is observed that all the identified lead indicators tend towards negative aspects or events in a project. However, the research considered the indicators to be neutral which can help to forecast both positive and negative aspects of a project. The results of the literature review reveal that Design Change, Communication, Decision Making, Level of Experience, Mood, Attitude, Commitment, Conflicts, Trust, Criticism and certain External indicators are the most important and frequently repeated KLIs. Based on the literature results and three case studies each one from Sweden, Netherlands and Austria respectively, interviewees from each case are asked to respond to the questions framed in order to identify the KLIs from practice. The results of the analysis confirm that almost all KLIs observed from literature are similarly observed in practice. Level of Experience of the project personnel and Close Stakeholder Engagement are found to be the most frequently repeating KLIs across all the projects. It is concluded that in order to improve the performance of future LIPs, the identified KLIs should be responded at the earliest by measuring and influencing them. Broadly, more attention should be paid on improving the recruitment process, prioritizing client’s requirements, empowering stakeholders, improving personal relationships and creating positive project environments. A detailed set of recommendations is provided as starting points to enable the required change. This research contributes to scientific knowledge of lead indicators in project management by enriching the concepts of KLIs and discovering steps to measure and influence them. It also contributes to practical knowledge in the industry by identifying the Lead Indicators large construction projects.