Second ring is the most jammed road in Beijing: A view from taxis and Weibo

The urban congestion in big cities becomes more and more serious in recent decades, especially for China, whose urbanization is experiencing a rapid growth. While at the same time, the huge volume of spatial-Temporal mobility trajectories generated by massive individuals indeed provides an unprecedented big-data window for understanding and solving this problem. In this paper, we detect the congestion of urban areas in Beijing at the level of road segment through taxi GPS data and surprisingly find that the Second Ring is the most jammed road. Moreover, the distributions of picking-ups and dropping-offs indicate that lots of hot spots gather around the Second Ring. According to our vehicle travel model, the traffic of the Second Ring is the highest when commute happens among these popular regions. We conclude that the distribution of hot spots in Beijing results in the tendency of congestion on the Second Ring, which plays an essential role in connecting these popular areas. Further explorations show that our conclusion can also be testified by the check-in data from Weibo, a Twitter-like service in China. Finally, we study the effect of urban expansion to traffic growth and reveal that the expansion would increase urban traffic pressure dramatically. Taking Beijing as an example, the flux of the Second Ring demonstrates a super linear rise with the increment of the taxi picking-ups, suggesting the decentralization of city function should be urgently considered in the future urban planning.