Vehicles in a queue affect each other, so the record of time-headway was made in motorcades. 377 data groups of time-headway were collected at north Jia Song Road in shanghai using stopwatch. The research was calibrated on “steady-flow” traffic operations. Vehicle arrangement has direct impact on time-headway and was a function of the proportion of trucks and trailers and the number of highway lanes. On the analysis, a function for the time-headway was created using proportion of trucks and trailers and the number of highway lanes. Time-headway is also the function of speed. The 2 dimensional charts indicates that when the speed gets to 45km / h or 75km / h, the trend line turns. The research also indicates that the passenger car equivalent(PCE) of unit passenger cars is no longer 1.00 when it comes to collective act.