*地点：腾讯会议ID：928 821 274 链接：https://meeting.tencent.com/s/AGFZ4MYVMV3c
The constructions of Riemann solutions for a second-order traffic flow model derived from a nonlinear Vlasov type kinetic model are displayed in fully explicit forms. In particular, a composite hyperbolic wave is obtained in the Riemann solution under the suitable initial condition, in which a delta contact discontinuity is attached on the wave-front of a rarefaction wave. Furthermore, the asymptotic behaviors of Riemann solutions are analyzed carefully as the parameter tends to zero. It is shown that the formation of delta shock wave is derived from the composite hyperbolic wave solution as well as the formation of vacuum state is deduced from the solution consisting of a 1-shock wave and a 2-contact discontinuity, which shows completely different behaviors in the current literature.