After 13 years of waiting, Bulgaria and Romania are to partially join the Europe's vast Schengen area of free movement on Sunday, opening up travel by air and sea without border checks.

But land border controls will remain in place due to Austria's opposition to the eastern European countries becoming full members of the Schengen zone for fear of an influx of asylum seekers.

Despite the partial membership, the lifting of controls at the two countries' air and sea borders is of significant symbolic value.

With Bulgaria and Romania joining from Sunday, the Schengen zone will comprise 29 members -- 25 of the 27 European Union member states, as well as Switzerland, Norway, Iceland and Liechtenstein.

According to the Romanian government, Schengen rules will apply to four sea ports and 17 airports, with the country's Otopeni airport near the capital Bucharest serving as the biggest hub for Schengen flights.

More staff ranging from border police to immigration officers will be deployed to airports to "support passengers and detect those who want to take advantage to leave Romania illegally," the government said.

Random checks will also be carried out to expose people with false documents and combat human trafficking, including of minors.

Bulgaria and Romania both hope to fully integrate into Schengen by the end of the year, but Austria has so far only relented about allowing them to join by air and sea.

Croatia, which joined the EU after Romania and Bulgaria, beat them in January 2023 by becoming Schengen's 27th member.

Created in 1985, more than 400 million people can travel freely inside the Schengen area without internal border controls.

While some have reason to celebrate, truck drivers, faced with endless queues at the borders with their European neighbors, feel left out.

Earlier this month, one of Romania's main road transporter unions called for "urgent measures" to achieve full Schengen integration as soon as possible, deploring huge financial losses caused by the long waits.

"Romanian hauliers have lost billions of euros every year, just because of long waiting times at borders," secretary general Radu Dinescu said.

(Cover: Trucks queue to enter to the Vidin-Calafat border point between Bulgaria and Romania, near Vidin, Bulgaria on March 25, 2024. /CFP)