Türkiye completed its longest and fastest metro line on Friday with the opening of the final section of the project that further expands Istanbul's rail transport network and strengthens links between the city center and its main airport.

President Recep Tayyip Erdoğan attended the inauguration of the 22-kilometer (13.7-mile) Halkalı-Arnavutköy section, the last phase of the project that he said would significantly improve transportation for millions of Istanbul residents.

The final leg brings the total length of the fully underground Gayrettepe-Istanbul Airport-Halkalı line to 69 km. The route includes 16 stations.

"We are weaving our city, one of the world's largest metropolises, with a population of 16 million and nearly 20 million annual visitors, stitch by stitch with a network of railways," Erdoğan told the opening ceremony.

Before the event, he inspected the line, telling reporters that it's "a manifestation of a modern vision."

The first 47-kilometer section was put into service gradually in recent years.

The Kağıthane-Istanbul Airport leg was inaugurated in late January 2023, the Kağıthane-Gayrettepe section was opened in late January 2024, while the Arnavutköy-Istanbul Airport leg was launched in March of the same year.

The opening of the Halkalı-Arnavutköy section marks the completion of "one of the longest metro lines not only in Türkiye but in the world," Erdoğan said.

The line will operate at speeds of up to 120 km per hour, making it Türkiye's fastest metro route and one of the longest underground airport metro connections in the world.

The newly opened section includes five stations: Ibn Haldun University, Kayaşehir, Olimpiyatköy, Halkalı Stadium and Halkalı.

With the addition of these stations, around 1.5 million residents in Istanbul's Başakşehir and Küçükçekmece districts will gain direct rail access to both the city center and Istanbul Airport.

The route is integrated with several major transportation networks.

At Halkalı station, passengers can connect to the Marmaray commuter rail system running beneath the Bosporus, high-speed rail services, the Halkalı-Bahçeşehir suburban line and the Yenikapı-Kirazlı-Halkalı metro line.

Additional transfers are available to the M3 metro line at Kayaşehir, the M9 line at Olimpiyatköy and the future M7 extension at Halkalı Stadium.

"Millions of our citizens now have easy access to central locations in Istanbul," said Erdoğan.

Travel times on the completed route will be significantly reduced, with journeys between Halkalı and Istanbul Airport estimated to take around 30 minutes and trips between Halkalı and Gayrettepe lasting 57 minutes.

The line also incorporates Türkiye's first domestically developed railway signalling system, produced by defense electronics company Aselsan.

The network will operate using a fully automated driverless system. Of the 25 train sets deployed on the route, 15 were manufactured to fully driverless standards.

The government estimates that the project will generate total economic benefits of 935 million euros (nearly $1.1 billion) by 2043 through time savings and lower road maintenance and operating costs.

Officials project that reduced traffic congestion alone will save travellers approximately 117 million hours over the period.