The Channel Tunnel also illustrates the funding problem that a tunnel cannot be built and funded in stages, so cost over-runs (such as experienced on the Channel Tunnel) cannot be spread over time.
The Channel Tunnel also illustrates a funding problem, that a tunnel, since it is an all-or-nothing project, cannot be built and funded in stages. Therefore cost over-runs (such as experienced on the Channel Tunnel) cannot be smoothed over time.