机构地区: 中山大学
出 处: 《交通运输系统工程与信息》 2013年第4期100-105,148,共7页
摘 要: 原有的组合配对Logit模型(Paired Combinatorial Logit,PCL)中相似性系数的确定方法缺乏必要的理论依据,模型的同一分布假设导致它难以表征道路感知误差的异方差特质.为克服这些不足,本文提出了基于Probit等效阻抗的配对组合Logit路径选择模型.模型分上下两层:下层的每一配对采用Probit二元选择法,引入正态分布以表征感知误差的异方差性并提高了计算的准确性;提出随机等效阻抗的概念并以Clark公式计算每一配对的等效阻抗,为相似性系数的计算提供了清晰的理论依据;上层模型采用计算简便的多项Logit模型,利用相对阻抗来缓解Logit模型的长短路缺陷,通过条件概率计算路径的选择概率.新模型综合了Probit模型计算准确及Logit模型计算简便的优点,在两者之间取得了合理的平衡.经典路网的数值计算结果表明,该模型比传统Logit模型更为合理. An improved paired combinatorial Logit route choice model with Probit-based equivalent route impedance is proposed to simplify the calculation and resolve the homoscedasticity problem of the Logit model. The model comprises a two-level structure: the lower level employs a binary Probit choice model to address the problem of route overlapping. Clark' s approximation for normal distribution is employed to compale the equivalent impendence for each route pair in the upper level. The homoscedasticity problem is resolved through the introduction of the normal distribution. The upper level is a classical muhinomial Logit model with relative impedance that reduces the defect of variance-homogeneity in the upper level. Theprobability of route selection is determined by marginal and conditional probabilities. The proposed model combines the advantages of both Probit and Logit models with close-form formulations, which can be easily calculated. Two numerical tests, which were performed on the well-known examples, indicate that the proposed model produces more reasonable and stable results.