The city's roads and subway lines are expected to experience severe traffic congestion in the two weeks leading up to the Spring Festival as residents flock back to their hometowns for the holiday, the local government said Monday.

As usual, the surge in traffic will come with the holiday rush, coupled with a projected increase in traffic accidents due to bad weather, according to a press release from the Shanghai Urban Construction and Communications Commission.

The commission estimated that the number of travelers leaving Shanghai from January 26 to March 6 will increase 5 percent over last year's total of 29 million. It advised residents to avoid taking the subway close to the city's airports and train stations during rush hours because of the crowds.

The commission estimated that traffic on the roads and metro lines will grow 1 percent month-on-month in January, following a 2 percent increase in December.

The number of auto accidents and breakdowns on Shanghai's elevated roads in December was up 8 percent from the previous year due to ugly winter weather. Authorities believe there will also be an increase in traffic problems this month during the evening rush hour.

The bad weather, such as hail, snow and rain, will also slow down the average speed of road traffic. In December, drivers drove about 4 percent slower on non-elevated roads downtown during the evening rush hour compared with the same period in 2011.