  Despite the vast amount of studies on pedestrian flow, the data concerning
high densities are still very inadequate. We organize one large-scale
pedestrian flow experiment on a ring corridor. With 278 participants, the
density as high as 9 m^(-2) is reached. In the uni-directional flow, four
different states are observed, including the free flow, congested state,
over-congested state and hyper-congested state. The features of the
hyper-congested state are similar to the "crowd turbulence" reported in the
empirical data of Helbing et al., and the transition between the stopped state
and the moving state can be found. The flow rates in the over-congested state
are nearly constant, due to the downstream propagation of pedestrian clusters.
In the bi-directional flow, three different types of lane formations are
observed in the experiment: (1) three lanes are directly formed ; (2) two lanes
are directly formed; (3) firstly three lanes are formed, and then they transit
into two lanes. After the lane formation, some interesting phenomena have been
observed, including the inhomogeneous distribution of pedestrians across the
lanes, and the formation and dissipation of localized crowd. Our study is
expected to help for better understanding and modeling the dynamics of high
density pedestrian flow.
