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

摘要：

货车集结过程的占用时间构成其在站停留时间的主要部分，其耗费是编组计 划优化的重要参数，对其规律研究具有现实意义.固定车组重量分组列车的集结过程构成 两个相互关联的成批到达、成批瞬时服务的排队系统.首先根据车流到达的不确定性，将 基本组和补轴组两个去向到达批中的车数和间隔时间都视为随机变量，假定二者分别服 从泊松分布和指数分布且相互独立；然后应用随机过程理论和数值计算方法量化测度.结 果表明：平均集结批次与固定重量正相关、与到达强度负相关，可由二者比值近似估计； 平均集结占用时间都与固定重量和到达间隔时间正相关、与到达强度负相关，可由固定 重量与车流频率的比值近似估计；集结占用时间越长，总集结耗费越大，且附加耗费所占 比例也越大.

关键词: 铁路运输, 分组列车, 集结, 随机过程, 数值计算