Parameter estimation on daily arrival distribution of waterway lock

The tonnages or barges of daily arrival at a waterway lock accord with normal distribution. The distribution parameters (mean and variance) were analyzed by using traffic survey. The relationship between the sample size and the precision of variance estimation was discussed, and the sensitivity of variance estimation on the calculation of daily arrival volume was analyzed. Analysis results show that when sample size is over 90, the deviation of variance estimation is mostly less than 5%, the theory is feasible. 6 tabs, 1 fig, 7 refs.