ESTIMATION OF DELAYS AT TRAFFIC SIGNALS FOR VARIABLE DEMAND CONDITIONS
ESTIMATION OF DELAYS AT TRAFFIC SIGNALS FOR VARIABLE DEMAND CONDITIONS
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DOI：
10.1016/0191-2615(93)90003-s
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发表时间：
1993-04-01
影响因子：
6.8
通讯作者：
ROUPHAIL, NM
中科院分区：
文献类型：
--
作者：
AKCELIK, R;ROUPHAIL, NM
提出了一种适用于可变需求条件下的信号交叉口延误模型。该模型适用于整个范围内的预期操作，包括高度过饱和的条件下，在分析期开始时的初始队列。所提出的模型澄清了几个问题有关的确定的高峰流量期间，以及期间之前和之后的高峰。提供了单独的公式，用于估计每个指定流量期间以及总流量期间的延迟。还提供了公式来估计过饱和期的持续时间（如适用）。该模型的优势在于使用简单的规则来确定峰值内外的流量，使用峰值流量因子，这是众所周知的峰值小时因子参数的概括。简单的规则也提供了识别的位置和持续时间的高峰流量期间的需求曲线的观察。这些信息被认为是至关重要的交叉口设计和评估的观点。该模型的各种操作条件下的应用表明，在高峰流量期间到达的车辆的估计延迟是一个可以接受的预测的平均延迟发生在总流量期间，即使过饱和持续超过总流量期间。另一方面，使用平均饱和度而不考虑峰值可能导致延迟的显著低估，特别是当在容量条件下或接近容量条件下操作时。这些发现得到了证实，通过比较模型的结果与文献中发现的其他模型。这项工作的重要贡献不仅在于改进延误估计，而且更重要的是，为估计过程提供了一个综合框架，该框架包括：（a）需求流模式中的峰值特征，（B）根据观测到的峰值，在总流量期内指定特定流量期，以及（c）在每个流动周期内以及与其它周期相结合的性能参数的估计。提出了美国公路通行能力手册（HCM）中的延误公式。与现行的HCM公式不同，修正后的公式对洪峰期饱和度没有限制。还建议将估计过饱和持续时间的简单公式与订正延迟公式结合使用。
This paper proposes a delay model for signalized intersections that is suitable for variable demand conditions. The model is applicable to the entire range of expected operations, including highly oversaturated conditions with initial queues at the start of the analysis period. The proposed model clarifies several issues related to the determination of the peak flow period, as well as the periods immediately preceding and following the peak. Separate formulas are provided for estimating delay in each of the designated flow periods as well as in the total flow period. Formulas are also provided to estimate the duration of the oversaturation period where applicable. The strength of the model lies in the use of simple rules for determining flow rates within and outside the peak, using the peak flow factor, a generalization of the well-known peak hour factor parameter. Simple rules are also provided for the identification of the location and duration of the peak flow period from observations of the demand profile. Such information is considered vital from an intersection design and evaluation viewpoint. Application of the model to a variety of operating conditions indicates that the estimated delay for vehicles arriving in the peak flow period is an acceptable predictor of the average delay incurred during the total flow period, even when oversaturation persists beyond the total flow period. On the other hand, the use of the average degree of saturation with no consideration of peaking can lead to significant underestimation of delay, particularly when operating at or near capacity conditions. These findings were confirmed by comparing the model results with other models found in the literature. The significant contribution of this work is not simply in the development of improved delay estimates, but, more important, in providing an integrated framework for an estimation process that incorporates (a) the peaking characteristics in the demand flow pattern, (b) the designation of flow-specific periods within the total flow period in accordance with the observed peaking and (c) the estimation of performance parameters associated within each flow period and in combination with other periods. A revised delay formula for the U.S. Highway Capacity Manual (HCM) is proposed. The revised formula has no constraints on the peak flow period degree of saturation, unlike the current HCM formula. It is also recommended that a simple formula for estimating the duration of oversaturation be used in conjunction with the revised delay formula.