The European Union wants to greatly boost rail connections to cut carbon emissions from air transport, with plans to double high-speed train traffic and link all big cities by 2030.

With stops in a dozen cities across five countries, the new line operated by European Sleeper -- a Dutch-Belgian startup -- is a poster child for such ambitions.

European lawmakers, the Italian and Austrian ambassadors and industry representatives attended a launch event with beer, bubbles and EU flags at a Brussels station ahead of departure Wednesday evening.

Yet, like the political hopes it represents, the train rubbed up against the fragmentation of the European network, which is broken into national systems with different rules and authorities.

A last-minute issue with the Italian rail management office left it unable to enter the country, the operator said.

Passengers had to disembark in Innsbruck, Austria, and hop on another train to complete their journey.

- Derailed plans -

It was the latest in a string of headaches for the firm that observers say underscore the challenges for rail to become a viable alternative to flying in Europe.

The first was securing financing to buy new carriages or renovate old ones, said European Sleeper co-founder Elmer van Buuren.

Private firms compete for funds with national rail operators backed by the public purse, which are a much preferred, low-risk option for investors, he lamented in an interview with AFP.

Risk would be lower if companies could secure a train path for a long period of time but that is currently not the case, he added.

"Every year you have to apply for capacity, every year you are uncertain if you will get it," he said.

Unable to secure funding, European Sleeper diverted some carriages from its established Brussels to Prague route.

The Venice train will run only six times between February and March -- low season on the Prague line -- hoping to attract skiers heading for the Alps.

Bureaucracy is another issue.

Under EU rules, national railway infrastructure managers should coordinate to ease cross-border travel.

But despite months of work and "hundreds of emails and phone calls" to five different authorities, European Sleeper secured a definitive timetable for its train only last week.

Then on Tuesday, the Italians pulled the plug on the last section of the route for unclear reasons, van Buuren said. Italy's rail infrastructure office did not immediately reply to a request for comment.

- 'Railway nationalism' -

Proponents say demand for train travel is high.

Night trains in France carried one million people in 2024, up 23 percent from the previous year, according to clean transport advocacy group T&E.

Several passengers on the Venice line cited climate concerns as a reason they decided against flying, which is much more polluting.

But they also complained about high rail prices.

A 2023 report by Greenpeace comparing the costs of flight and train tickets on 112 European routes found trains were on average twice as expensive.

Rail sector operators blame a decades-long tax exemption on commercial aviation fuel.

"As long as kerosene is not taxed, rail cannot compete on an equal footing," said Enno Wiebe, head of the Union of European Railway Industries.

Cutting red tape would also help, he added, complaining that vehicles need to be "re-authorised" -- a months-long process -- after changes affecting anything from engines to trains' interior design.

More competition would be another boon, said Victor Thevenet of T&E.

The EU is investing billions in upgrading and integrating railways, pushing a single European signalling system that will replace the current mix of national systems and smooth traffic.

But national authorities are often reluctant to expose public operators to external competition, critics say.

A 2024 EU report by former Italian prime minister Enrico Letta criticised national tax incentives that disadvantage international operators.

EU plans for a single booking system allowing passengers to buy one ticket for a journey supported by different national rail operators are facing strenuous resistance.

"We need to finish with the railway nationalism," Kristian Schmidt, the European Commission director for land transport, told the Venice sleeper launch event on Wednesday.

Train users are patiently waiting.

"The change was not super well communicated," Benoit Cambier, a passenger on the maiden Venice trip, said of the Innsbruck hiccup. "The view and trip are great though".