Belgrade-Budapest Fast Rail: 14-Day Signal Test Before Fall

Testing of the signal system with live trains in real traffic on the Budapest, Deledjhaza, Kelebija, Belgrade section began the day before the two ministers met in Subotica, and it has to run for two weeks before an opening date can even be announced. The deadline was laid out after that meeting by Hungarian minister of transport and public works David Vitezi, who added the caveat that early fall is realistic only if the software passes without objections.

That timeline lines up, for the first time, with what has been announced on the Serbian side. Serbia’s minister of construction, transport and infrastructure Aleksandra Sofronijevic said in Subotica that after August 24, once the test runs are finished, a simulation trip from Belgrade to Budapest and back will be carried out, with all border and customs procedures included, in order to measure the final travel times. The sequence is now set:

• signal system testing with live trains, two weeks from the start of this week
• a simulation run over the full route, after August 24
• announcement of the exact date and launch of passenger service, early fall

The Belgrade-Budapest fast rail line is now at a stage where only the software is still lagging, not the construction. Vitezi said freight traffic on the line is already running without interruption, which shows the infrastructure side of the job is functional.

What exactly is being tested for two weeks?

Under review is the signaling and safety system supplied by a Chinese contractor, procured back under the previous Hungarian government. Office checks of the software have been completed, and the system is now being observed in operation, with trains running to schedule.

“The problem isn’t that it wasn’t done well, it’s that it still hasn’t been delivered by the Chinese company contracted under the previous Hungarian government, but that too is in its final phase. The software has been delivered, office checks of the software have been completed, and the so called ‘dark mode’ testing, that’s what we call it in Hungarian, meaning testing in real traffic, live on trains, started yesterday,” Vitezi explained.

The outcome of that test is a condition, not a formality. The minister was explicit that any objections mean nothing opens:

So far it’s going well. The trains have to run for two weeks to establish that the software systems are working properly. After that, if everything is fine, we can announce an opening date for the line. If there are any safety issues, they will have to be resolved because that’s what the contract requires, that’s why I’m being careful when I talk about opening the line, but if everything goes well, it will happen in fall, in the earlier part of fall.

Trains on the line can run at speeds up to 160 kilometers per hour. Reconstruction work began in 2022, and the launch date has been pushed back several times since then, always because of the system, never because of the track.

Kelebija: 16 police officers on board and a 30 minute border crossing

It has been agreed that border checks will take place in Kelebija, right at the border, rather than at the departure or arrival station. The Hungarian side is taking on the harder part of the job, since entering the Schengen area is a longer procedure than leaving it.

The plan calls for 16 Hungarian border police officers to be on the same train, with the goal of keeping the stop in Kelebija under 30 minutes. For passengers, that number is the one that ultimately decides whether the train is worth it over a car: time at the border counts toward total travel time just like the ride itself.

The trains will be combined services, Hungarian locomotive hauled consists and Serbian electric multiple units, and both sides are aiming for a frequent Belgrade, Budapest line, extending on to Vienna. The timetable still needs to be worked out.

Chinese documentation still classified

An open question running in parallel with the tests is the secrecy around the project documentation. The previous ruling coalition of Fides and KDNP decided in 2020 to classify the documentation for ten years, citing Hungary’s foreign policy and foreign trade interests. The new government has formally asked the Chinese side to lift that classification.

We asked the Chinese to let us make that documentation public, but they haven’t done so yet. We requested it officially, but we still haven’t received an answer. As a state we do have access to those documents, a review of what happened earlier is underway, but it will certainly not delay the opening of the line for passenger traffic.

Vitezi has previously said the Hungarian section was, at its core, poorly designed and built, and that large sums were sunk into it. That review, however, remains separate from the opening deadline, a point both delegations repeated in Subotica.

The same meeting also touched on the road link. Hungary is looking at reviving the project to expand the Herceg-Santo border crossing, which would connect Serbia to the M6 motorway on the other side of the Danube. Vitezi also pointed to the historically low water level of the Danube in Hungary and said climate change adds another argument for rail, since river transport loses reliability exactly when it’s needed most.

The next checkpoint is the simulation run after August 24. That will be the first time travel time is measured over the full route, with the border check in Kelebija counted into the total.