关键词: 铁路运输, 分组列车, 集结, 随机过程, 数值计算

Abstract:

Occupation time of accumulation process constitutes the main part of railcars’stay in stations, and its cost is one of important optimization parameters for formation train plan (TFP), so it is of significant practical meaning to research on its law(s). In fact, accumulation process of multi- block trains with fixed weight can be regarded as two interrelated queuing sub-systems with batch arrival and batch instantaneous service. Firstly, according to the uncertainty of railcars’arrival, both the size and interval time of basic-block (i.e. long-distance block) and complementary-block (i.e. short-distance block) are considered as independent random variables obeying Poisson and exponential distribution, respectively. Then, accumulation’s characteristics in three aspects are measured applying stochastic process theories and numerical calculation. It comes to some conclusions: the average accumulation batch is positively correlated to fixed weight, and negatively related to the wagon flow intensity, so it can be estimated approximately by their ratio; the average occupation time during accumulation can be evaluated approximately by the ratio between fixed weight and wagon flow frequency, due to positively correlating to fixed weight and average interval time and negatively correlating to the wagon flow intensity; the longer the accumulation time lasts, the larger both the total accumulation cost and the proportion of additional cost will be.

Key words: railway transportation, multi-block train, accumulation, stochastic process, numerical calculation