This photo taken on Sept. 29, 2023 shows passengers at Zhengzhou Railway Station in Zhengzhou, central China's Henan Province. [Photo/Xinhua]

Hundreds of millions of trips are expected to be made in China during the eight-day public holiday, which officially started on Friday, authorities said.

The Mid-Autumn Festival and National Day holiday is the longest public holiday break since China optimized its COVID-19 response measures late last year.

On Friday, some 66 million cars were predicted to hit roads nationwide, the Ministry of Transport said.

Topics involving traffic jams have been trending on social media.

Netizens have posted video clips on microblogging service Sina Weibo, showing flyovers jammed with crawling cars. Some even shared videos showing people caught in highway traffic jams sitting by the side of the road playing mahjong.

Some 190 million train trips are forecast to be made from Wednesday to Oct. 8, which takes in the Mid-Autumn Festival on Friday and National Day on Sunday.

Each day, 15 million people on average are expected to crisscross China via the country's sprawling railway network for sightseeing and family reunions, said the China State Railway Group. In 2019, 138 million rail trips were made during the same period, official data showed.

Friday was expected to seek the peak, with more than 20 million rail trips, the group said in a statement.

The Ministry of Transport has forecast that a total of 490 million total trips would be made during the holiday travel rush, a 78.6 percent year-on-year increase.