The UK National Audit Office (NAO) have recently published a very useful interactive PDF NAO framework to capture the key questions that need to be addressed at each stage of a project. It recrafts the lists of gateway questions and aligns them with a range of case studies from the NAO’s back catalogue. It may take weeks of effort to go through all the links and extract the relevant salient points for your project or programme, but it is a very useful introduction that provides high level insights on where to direct your lessons learned efforts.Its a great starting point.
If you do have an interest in leveraging the experiences from similar projects I would caution against restricting your analysis to this material alone. There is also a rich dataset of information available on the US GAO , Canadian auditor, Australia an NZ websites. This is supplemented by lessons learned reports, case studies, public hearings (such as the Edinburgh tram) and public accounts committees (such as NHS24).