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Capacity has traditionally been defined deterministically, and has been assumed to occur immediately before breakdown. Recent studies, however, have shown that the value of capacity, i.e., maximum throughput, is probabilistic, and does not always occur immediately before the breakdown. Four different types of flows (i.e., maximum prebreakdown flow, breakdown flow, maximum queue discharge flow, and average queue discharge flow) referred to as “capacity flows” in this paper, are considered to examine how they differ by day of the week and time of the day, and whether they are significantly different by type of freeway segment. Speed and volume data were obtained, which were initially collected by remote traffic microwave sensors at the US-202 southbound near Philadelphia, from May to August 2004. The four types of flows described above were collected and distinguished by time period, day of the week, and segment type. In conclusion, the mean capacity flows were different during different times of the day, but were the same each day of the week. In comparing segment types, capacity flows per lane are generally not equal between merging, diverging, weaving, and lane drop segments. [ABSTRACT FROM AUTHOR]

Weaving areas are one of the major highway facilities that have long been investigated by researchers. Their capacities are currently estimated based on the density 27 pc/km/ln. There is no specific reason why this method can produce accurate estimates. In addition, no data collection has been performed to validate them. This study develops a generalized capacity estimation model for weaving areas, which is applicable to the entire range of configurations of weaving areas, and compares the resulting capacity estimates to field estimates. The proposed methodology is based on gap acceptance theory and linear programming techniques. Speed and flow data over several days were obtained and analyzed to extract the capacity of three study sites along the QE Expressway, Toronto. It was found that, for the three study sites, the proposed methodology provides capacity estimates that are closer to the field-observed capacity values than the Highway Capacity Manual (2000) estimates. [ABSTRACT FROM AUTHOR]

Chapter 16 of the Highway Capacity Manual 2000 (HCM 2000) includes models and procedures for calculating capacity and delay at signalized intersections. However, the procedures do not provide estimation of the optimal cycle length which would result in the minimal intersection delay. A quick estimation method for determining the cycle length is described in Appendix A, Chap. 10 of the HCM 2000 for planning level applications. In this method, a simple equation is used to estimate the cycle length if it is not available. However, the estimated cycle length may not be the optimal cycle length from the point of view of achieving minimum intersection delay. To develop a new cycle length model, the Webster’s minimum delay cycle length model is first considered. However, based on our study, Webster’s minimum delay cycle length model overestimates the optimal cycle length compared to the results from the HCM 2000 delay calculation method, especially under high traffic volume conditions. After investigating three new models developed during this study, an exponential-type cycle length model is recommended. Based on a series of CORSIM simulation runs, the cycle length predicted by this model provides better results than the current quick estimation method of the HCM 2000. [ABSTRACT FROM AUTHOR]