Study On Reasonable Value Of The Buffer Time In Railway Passenger Dedicated Line Train Diagram

The service level of passenger special line is much higher than the existing railways with its comfortableness, conveniences, safety, high velocity and high punctuality rate. To ensure that, on one hand, there must have advanced equipments and facilities and high level personnel, on the other hand, there must be a strong elastic train diagram which can make the delayed train resumed as soon as possible and try to weaken or avoid the influence for the other trains through its buffer time. But the buffer time is at the cost of carrying capacity that the value of it must be reasonable because too much buffer time will waste the carrying capacity and too less will increase the probability of train delay.Owing to the train delay while the train’s actual interval running time and stop time were deviated to the determined time, this paper suggested to add buffer time between trains in double track automatic block districts to increase the elasticity of train diagram. This paper described the skewness distribution of train deviation by lognormal distribution, deduced the formula of disturbance probability, established a model between buffer time, disturbance probability and delaying time probability, and calculated the reasonable value of buffer time. According to the main influence factors, this paper analyzed that the main reasons for train delay were the time disturbances due to train running or the operations in station. The train deviation happened inevitably and through the analysis of it, this paper described the relationship of buffer time tr, random disturbance variable δ and disturbance probability p. Then this paper researched the distribution of deviation which was thought to be skewness distribution and could be described by lognormal distribution through the verification of x-, according to the analysis of lognormal distribution function, there came the formula of disturbance probability represented by buffer time tr and random disturbance variable δ. After that, this paper studied the probability of train delay and obtained the formula by assuming it to have negative exponential distribution. For another, this paper analyzed the value of buffer time which was thought to be reasonable when the delay probability of train j influenced by the front train was less than the delay probability of train J itself and the delay probability of train j was less than the disturbance probability between train J and the behind train. And this paper calculated the reasonable value of buffer time on condition of certain carrying capacity standard、average minimum time interval and the minimum total number of the train delayed.At last, this paper took the district from Changsha to Zhuzhou on Wuhan-Guangzhou passenger special line for example and calculated the reasonable value of buffer time.