Forecasting the success of megaprojects with judgmental methods: the role of expertise, stakeholder perspectives, and implications for socio-economic planning

Forecasting the success of megaprojects is a very difficult task because of the complexity of such projects. Some scholars argue that forecasting is not really needed in this context: the master Gantt chart with tasks and allocated person-hours, and the respective Bill of Materials, should suffice for an accurate estimation of the duration and cost of a project. If that was however the case, then projects would finish on time and budget – but this is far from true, as the numerous examples attest: HS2, Channel Tunnel, IT public projects in NHS, to name a few. In this research, we employ judgmental forecasting methods to predict the success of a megaproject (‘constructing a major recreational facility in the city centre of a metropolis’). We evaluate separately the forecasted excesses in the budget and the duration of the project. Furthermore, the participants forecast the extent to which the socio-economic benefits are realised. We do analyse three different stakeholder perspectives: that of the a) project manager, b) funder(s), and c) the public. We do also examine two levels of expertise – novices, and semi-experts. Finally, we discuss the implications for socio-economic planning and the potential integration with data driven methodologies while considering wider megaproject settings and contexts.