Certainly, the plans polarised opinions. Those in the anti-HS2 camp claimed there was a poor business case underpinning the scheme and questioned the true fiscal value of shortening journey times, while the pro-HS2 camp pointed to a boost in economic development across the country. At times, the public-relations battle turned nasty, with rhetoric from both sides drifting from the implausible to the bizarre - claims of creating a million new jobs were clearly over-optimistic.

Amidst the kerfuffle one might have been forgiven for thinking that Britain was taking a leap of faith into the unknown, but this is not the case. Whilst Britain may still be taking its first infant steps, as the only high-speed line completed so far links the Channel Tunnel with London (HS1), high-speed rail technology is nearly 50 years old, starting with the Japanese Shinkansen, which opened to coincide with the 1964 Tokyo Olympics. Now that the dust is settling on the decision to proceed with HS2, what can we draw from examples elsewhere for a cool-headed assessment of HS2's potential impact on British travel habits?

In addition to Japan, the established national high-speed networks are found in France, Germany, Italy and, more recently, in Spain and China. Beyond these systems, high-speed rail tends to be limited to a few hundred kilometres here and there.

The experience of these countries shows that high-speed rail holds a clear advantage over air or road travel for journeys of around two to three hours. According to the International Union of Railways (UIC), high-speed services account for 80% of journeys, when compared with air travel, where travel time by train is less than 2h 30min.

Britain's national and economic geography could barely be better suited. With no major rivers to cross or mountains to tunnel, three of Britain's leading economic and transport hubs - London, Birmingham, Manchester - can be connected with around 480km of track. Most European railways would see that as a bargain. Indeed the distance between London and Birmingham is around the same as one of Europe's most successful high-speed lines that connects Frankfurt and Cologne.

And linking key national centres is essential. In Japan, the Shinkansen now carries four out of five journeys between Tokyo and Osaka. In Spain, rail is the main transport mode along corridors such as the recently-opened Madrid - Barcelona route.

Other criticisms of the HS2 business case, such as technological developments creating less demand for transport connections, or that only rich businessmen with deep pockets will travel by high-speed train, are equally unproven.

There has been no research proving that we will gradually become less inclined to leave our neighbourhoods - transport demand has historically only gone in one direction: up. Growth in demand for mobile technology suggests people increasingly expect to stay connected whilst on the move, rather than not moving at all. Nor is there any proof that ticket prices will be high. One might expect peak travel on HS2 to be pricey. But providing new capacity is just as likely to increase competition with services on the existing West Coast Line. Market forces may keep prices within reason.

Less clear-cut is proof of high-speed rail boosting regional development and economic inequalities. International evidence shows a double-edged impact: often the effect has been to strengthen the advantage of an already dominant city. The opening of Spain's first AVE line in 1992 caused Madrid's business population to swell at the expense of Seville. And more businesses have relocated their headquarters to Paris since TGV linked it with the regions. Even the analysis of Britain's own government predicts that 70% of the new jobs created by HS2 will be in the southeast of England which includes London.

But there are clear cases where regional centres have been boosted by high-speed rail. Lille, in northwest France, suffered severe industrial decline in the 1970s. But it has since been transformed with a new service-led authority after becoming a major crossroad in the European high-speed rail network with connections to Paris, London and Brussels. Zaragoza was a low-profile city in northeast Spain until it was incorporated into the Spanish network in 2003, subsequently hosting Expo 2008.

Of course predicting the impact of an infrastructure project of this scale is always, to some degree, a shot in the dark. Any measure you choose – patronage, reduction of car use, impact on air routes, carbon emissions – are, at best, informed guesses.

The devil is often in the detail. Much will depend on the less glamorous areas such as route planning, procurement and achieving operational efficiencies. But initial assessment shows Britain has the geography and the scale for high-speed rail to make a positive investment in its future. After all, we do not know what tomorrow will bring, but history shows that we tend to speed up rather than slow down.