Abstract:A research was made of the cell transmission models on city expressway.The Pattern cell transmission model (CTM) was proposed based on that the observability of traffic flows’ dynamic characteristic appeared to be different according the transmission methods of traffic information under different patterns of road traffic state.In Pattern CTM cell transmission model,the flow transmission model on mainroad was updated to be expressed as the form of piecewise function and the flow transmission model on offramp was constructed against the city expressway.Taking the real data on Shanghai NorthSouth Expressway as example,the performance of three CTMs were compared.The result shows that the Pattern CTM is the best of all.When the Pattern CTM is applied in large scales,the mean percent error (MPE) of density is around 20% and the MPE of flow is around 10%,which show that the simulation result is satisfactory.