Every project relies on forecasts, both for justification and as an aid to planning. Most take growth rates from the immediate past and extrapolate them into the future. They do not always turn out to be accurate. In 1971 the «Rail Tunnel through the Alps» commission concludes that passenger traffic through the Alps will increase by at least 50% between 1963 and 1990 while goods traffic will actually double. In fact, the volume of goods transported by road and rail grows by around 200%. There are exceptions, though: the Federal Council’s 1990 dispatch on the «Construction of the Swiss rail link through the Alps» predicts a further doubling of goods traffic and a 50% rise in passenger traffic by 2020. That forecast proves to be spot on.
« However, it is not objectively possible to comment on the probability of a given scenario occurring. »St. Gallen Centre for Futurology, Study on the prospects for goods traffic through the Alps 1993–2015, 1994