It includes a total of 28 stations serving the Tamsui, Beitou, Shilin, Datong, Zhongshan, Zhongzheng, Daan, and Xinyi districts.

At 29 km (18 mi), it is currently the longest line of the Taipei Metro.

Most of the tracks and stations have been renovated there, except in the Zhongzheng district, where a new tunnel was constructed due to a lack of surface right-of-way.

The Red line is a high-capacity rapid transit system.

For 15 years, trains operated between Tamsui and Xindian via the southern part of the current Songshan–Xindian line, making it the longest-serving former service of the system, followed closely by a 13 year service from Beitou to Nanshijiao via the southern part of the current Zhonghe–Xinlu line.