The mobile phone applications for metro lines in Hohhot, capital of North China's Inner Mongolia autonomous region, and Tianjin municipality were interconnected on Jan 28. 

It is the third city following Beijing and Shanghai to set up mutual access of metro line apps with Hohhot. 

Through internet technology, urban rail transits in Hohhot and Tianjin have worked together to promote the integrated development of urban rail transit and ticket sharing.

Citizens of Hohhot and Tianjin can now use the "Qingcheng Metro" app or the "Tianjin Metro" app to take metro lines in both cities, which will facilitate cross-city transportation and promote green travel and the coordinated development of the two cities.