A tour bus that preserves the classic look of the Dangdang trolley passes Tian'anmen Square. [Xinhua]

The second "Dangdang" trolley sightseeing route will be put into use on March 18, after Beijingintroduced the vintage vehicles last year to carry tourists through iconic downtown attractions.

Ten trolleys are set to serve the new line and will be powered with electricity as well. Based on three major stops – Qianmen, Tian'anmen Square and the Palace Museum, the 10-kilometer-long bus route starts at Qianmen and will return to the departure station after 15 stops.

Passengers on each trolley will be accompanied by a tour guide, introducing scenic spots and historical sites in both Chinese and English.

The fist "Dangdang" trolley route starts near south Beijing's Yongdingmen gate tower, passing more than 20 scenic spots, including the Temple of Heavenand Tian'anmen Square, and forms a circle along the axis of Beijing.

The bus line operates between 8:30 am and 5 pm during the off season (October to April) and 8 am-5 pm during peak season. It costs a single fare of 15 yuan ($2.40) by cash, or 10 yuan by transportation IC card. The buses are scheduled for every five to 10 minutes.

Painted in bright colors, the buses are replicas of those used in Beijing from 1924 to 1966. At that time, trolley drivers had to ring copper bells as horns to alert pedestrians, and people started to call the vehicles "Dangdang" because of the sound the bells made.

The first batch of 12 "Dangdang" trolleys have made 7,100 trips and received more than 250,000 passengers since their inception in September.