Many high profile projects have been in the news recently. Talk about the spirally costs, impact on the environment and whether the concepts actually work have all been mentioned more than once.
The national audit office has branded at least a third of these projects as 'undeliverable' or 'in doubt'
The telegraph has put together an outline of the challenges faced and the impact of success/failure
The projects, which could include the HS2 rail line and Hinkley Point nuclear power station, run the risk of missing targets because of 'unrealistic expectations', the National Audit Office has said