Quantifying distributions of freeway operational metrics

Boyles, Stephen D.; Voruganti, Avinash; Waller, S. Travis

doi:10.3328/tl.2011.03.01.21-36

Cited by 5 publications

(3 citation statements)

References 17 publications

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“…It is clear that a small change in flow of such bottleneck links may encourage some travelers to search for cheaper routes. This is related to the concept of intrinsic sensitivity, defined in Boyles et al (2011).…”

Section: Network Interactionsmentioning

confidence: 99%

Improved bush-based methods for network contraction

Jafari

Boyles

2016

Transportation Research Part B: Methodological

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Calculating equilibrium sensitivity on a bush can be done very efficiently, and serve as the basis for a network contraction procedure. The contracted network (a simplified network with a few nodes and links) approximates the behavior of the full network but with less complexity. The network contraction method can be advantageous in network design applications where many equilibrium problems must be solved for different design scenarios. The network contraction procedure can also be used to increase the accuracy of subnetwork analysis. This method requires calculating travel time derivatives between two nodes, with respect to the demand between them, assuming that the flow distributes in a way that equilibrium is maintained. Previous research describes two methods for calculating these derivatives. This paper presents a third method, which is simpler, faster, and just as accurate. The method presented in this paper reformulates the linear system of equations defining these sensitivities as the solution to a convex programming problem, which can be solved by making minor modifications to static user equilibrium algorithms. In addition, the model is extended to capture the interactions between the path travel times and network flows, and a heuristic is proposed to compute these interactions. The accuracy and complexity of the proposed methodology are evaluated using the network of Barcelona, Spain. Further, numerical experiments on the Austin, Texas regional network validate its performance for subnetwork analysis applications.

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Section: Network Interactionsmentioning

confidence: 99%

Improved bush-based methods for network contraction

Jafari

Boyles

2016

Transportation Research Part B: Methodological

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“…A further distinction in location can be made using bottleneck types. A large number of papers have investigated capacity values for specific bottleneck types . The bottleneck types are indicated in this research but are not explicitly considered for their effect on capacity values because of the limited sample size per segment type.…”

Section: Conceptual Model Of Capacity Variationmentioning

confidence: 99%

Quantification of motorway capacity variation: influence of day type specific variation and capacity drop

Calvert

Taale

Hoogendoorn

2015

J of Advced Transportation

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SUMMARYMany road authorities work with static values for road capacities, while it has been proven that capacity is not a fixed quantity. At the same time, there is an increasing need for accurate stochastic input for traffic models, such as the variation in road capacity. In this paper, a methodological framework with a conceptual model for practical stochastic capacity estimation is presented, and a quantification of motorway capacity variation is given for the influence of day-type specific variations in capacity values. The results of the analysis show that there is a reduction in motorway breakdown capacity of 4% on weekend days in comparison with workdays. Furthermore, a capacity decrease of 8% was found for the discharge capacity in comparison with workdays. The analysis further shows that the breakdown capacity on holidays is not significantly lower than on workdays. Discharge capacity and capacity drops are also derived in each case. The results show that the capacity is significantly different depending on the type of day. A quantification of these differences is given in the form of a Weibull capacity estimation fit for each type-of-day scenario. Further consideration of the implications and applications of the framework is also given.

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“…We also assume that the number of cross roads within the road segment follows a Poisson distribution with a parameter λ c . Practical values of λ c can be obtained from [21], which provides measured statistics to the density of interchanges (road junctions) for some major cities in the United States. As a result, the vehicle will leave the road segment within a distance of y with probability p l (y), which can be manipulated using (9) to obtain…”

Section: Exact Analysis For One Replica and Known Distributionsmentioning

confidence: 99%

Delay Analysis for Sparse Vehicular Sensor Networks with Reliability Considerations

Abdrabou

Liang

Zhuang

2013

IEEE Trans. Wireless Commun.

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-This paper addresses the relation between message delivery delay and reliability for the communication between a vehicle and a road side unit (RSU). We focus on sparse vehicular sensor networks (VSNs), where timely message delivery and reliable transmission are of significant importance. We present a mathematical framework for the message delivery delay distribution for a two-lane road, where vehicles in one direction act as message carriers for the ones in the other direction and have the freedom to leave the road from randomly distributed road junctions with a certain probability. Packet generator vehicles store the original packets till meeting an RSU while sending multiple copies of each packet to packet carrier vehicles. Our analysis offers an analytical tool for an intelligent transportation system (ITS) service provider to determine the minimum RSU density required to cover a road for meeting a probabilistic requirement of the message delay.Extensive computer simulation results show the accuracy of our analysis and clearly indicate the relation of packet delay and the number of packet replicas.Index Terms -Delay, vehicular sensor networks, vehicle-to-infrastructure transmission, disrupted connectivity, road side unit placement, information delivery reliability.

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Quantifying distributions of freeway operational metrics

Cited by 5 publications

References 17 publications

Improved bush-based methods for network contraction

Improved bush-based methods for network contraction

Quantification of motorway capacity variation: influence of day type specific variation and capacity drop

Delay Analysis for Sparse Vehicular Sensor Networks with Reliability Considerations

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