Beijing's annual peak week for road congestion got even worse on Monday when a major subway line suffered a malfunction during morning rush hour.

Services on Line 4 experienced delays from 7 to 9 am due to signal problems, operator Beijing MTR Corp said.

The interval between trains on the line and its extension, the Daxing Line, were extended and many passengers were stranded in stations.

The 28.2-km north-south line is one of Beijing's busiest, with 1.3 million average daily trips, according to the operator.

Traffic jams were caused when many people opted to take other transportation instead.

Many commuters complained about gridlock online, and operations gradually returned to normal after 9 am.

The company apologized for the malfunction on its website and issued a letter of apology to commuters who did not arrive at work on time.

Beijing is predicted to experience its worst traffic congestion this week, with the Mid-Autumn Festival falling on Thursday.

It has become popular for people to send gifts on the holiday, and many cars from outside Beijing are expected to enter the capital.

The city's transport commission estimated on Monday that traffic congestion will last for more than eight hours a day on Tuesday and Wednesday, while the evening rush hour may last until 8 pm.

Daily trips on the subway could reach 10 million during the three-day Mid-Autumn Festival starting on Thursday, while during the National Day holiday from Oct 1 to 7, it could be 8 million a day, said Jia Peng, spokesman for Beijing Mass Transit Railway Operation Corp, which operates 14 lines.

Subway authorities have prepared extra trains for the holidays on key routes, and more personnel will be assigned to maintain order, the transport commission said.

For the ground transport system, 19,000 buses will be in service to meet demand, the authority said.

The peak congestion week coincides with "Green Transport Week", which launched nationwide on Monday.

The Beijing Transport Commission pledged to attract more people to use public transportation rather than private cars.

During World Car Free Day on Sunday, employees with the authority were urged to commute using public transportation.

The capital is also preparing for more tourists and road capacity as Beijing expects a surge in travel during the National Day holiday.

Considering the sudden increase of passengers and traffic flow in the city during the vacation, partly thanks to a toll-free highways policy, Beijing will further supplement its public transportation volume based on the monitoring data of festival passenger flow, the commission said.

The authority also vowed to further conduct safety inspections of public transportation vehicles to ensure road safety.

"It's necessary the capital prepares itself well before embracing visitors from all over the country during the holiday," said Deputy Mayor Cheng Hong. "Proper handling of emergencies is as important."

Contact the writers at jinhaixing@chinadaily.com.cn and zhengxin@chinadaily.com.cn

(China Daily USA 09/17/2013 page6)