Heavy rain flooded parts of Istanbul on Tuesday, clogging roads on the city’s Asian side, shutting a key stretch of the D-100 highway and causing serious traffic disruption across Turkey’s biggest city.

The downpour, which intensified after starting overnight, hit Tuzla and Pendik hardest. The Istanbul Metropolitan Municipality said overall traffic congestion reached 80 percent, with the Asian side far worse off than the European side.

Roads, underpasses and commuter routes were hit first

Floodwater turned streets, boulevards and underpasses into traps for drivers on the Asian side. Vehicles were left stranded in pooled water, while many commuters faced slow travel to work and school.

In Tuzla and Pendik, large amounts of water spilled across major roads and made movement difficult through the morning. The Turkish Meteorological Service had already warned that rain would strengthen early on 27 October.

Key highway section closed in Tuzla-Pendik direction

A section of the D-100, one of Istanbul’s main highways, was closed in the Tuzla-to-Pendik direction, including both the main and local carriageways. Traffic was diverted to Aydınlı Street, according to the Istanbul Metropolitan Municipality’s transport management center.

The closure added pressure to already crowded routes. Traffic jams formed in several districts, and movement on main roads became stop-start and slow. The municipality said congestion reached 89 percent on the Asian side and 71 percent on the European side.

Disruption was also reported on the D-100 and TEM highways, as well as on approaches to the Bosphorus bridges, which link Istanbul’s Asian and European sides.

Sabiha Gökçen Airport’s access tunnel filled with water

Flooding also reached Sabiha Gökçen Airport on Istanbul’s Asian side. Water entered the tunnel that provides access to the airport’s technical area, making it harder for staff to reach work and delaying shift changes.

One report said staff minibuses, a truck and several motorcycles were unable to move through the tunnel, with some drivers waiting for about three hours. Another report said water also gathered in part of a tunnel at the airport’s cargo terminal. Airport management had not commented at the time of publication.

Warnings were in place before the morning rush

Authorities had already put Istanbul under a yellow-code weather warning for Tuesday, warning of strong morning rain, flash flooding, inundation and transport disruption. The warning covered strong morning rain after the overnight downpour intensified.

Separate reporting said emergency teams rescued a driver and a child trapped in a flooded underpass in Kaynarca, also on Istanbul’s Asian side. Another report cited morning measurements showing the heaviest rainfall at Darlık in Şile, with 83.9 kilograms per square metre recorded there.

The weather was expected to continue through the day. The Istanbul Disaster Coordination Center said more than 8,000 personnel and nearly 2,400 vehicles had been deployed to address possible effects of the storm and heavy rain.