Simple, Generalized Method for Analysis of Traffic Queue Upstream of a Bottleneck

1998 ◽  
Vol 1646 (1) ◽  
pp. 132-140 ◽  
Author(s):  
Alan L. Erera ◽  
Tim W. Lawson ◽  
Carlos F. Daganzo
Keyword(s):  
Traffic Flow ◽  
Piecewise Linear ◽  
Wave Theory ◽  
Flow Density ◽  
Cumulative Number ◽  
Kinematic Wave ◽  
Input Output ◽  
Original Technique ◽  
Time Space ◽  
Bottleneck Capacity

An approach is generalized for enhancing a standard input-output diagram to represent graphically the time and distance that vehicles spend in a queue upstream of a bottleneck. The approach requires the construction of a curve depicting the cumulative number of vehicles to have reached the back of the queue as a function of time. The original technique, described in a previous paper, is reviewed for bottlenecks with constant capacity and for those where capacity changes once. The approach is then generalized to allow multiple changes in bottleneck capacity, and the original assumption of a triangular flow-density ( q-k) relation is relaxed to one that is piecewise-linear concave. Although it is consistent with the kinematic wave theory of traffic flow, the proposed approach is simpler to apply to complex problems because it avoids the laborious construction of a time-space diagram. It allows the estimation of several measures required in the evaluation of the impacts of bottlenecks, including the (accurate) number of vehicles in queue and the physical extents of queues at any time and the total time spent by vehicles in different traffic states.

Using Input-Output Diagram To Determine Spatial and Temporal Extents of a Queue Upstream of a Bottleneck

1997 ◽  
Vol 1572 (1) ◽  
pp. 140-147 ◽  
Author(s):  
Tim W. Lawson ◽  
David J. Lovell ◽  
Carlos F. Daganzo
Keyword(s):  
Simple Approach ◽  
Traffic Signal ◽  
Maximum Length ◽  
Cumulative Number ◽  
Input Output ◽  
Time Space ◽  
The Difference ◽  
Bottleneck Capacity

A simple approach is described for modifying an input-output (or queue-ing) diagram to measure the time and distance spent by vehicles in a queue in a much simpler and self-serving manner than a time-space diagram. The graphic technique requires construction of a curve depicting the cumulative number of vehicles to have reached the back of the queue as a function of time, but, as indicated here, the technique can be easily automated with a spreadsheet. The technique is applied to the simple case of a constant departure rate from a bottleneck and to the slightly more general case of a bottleneck capacity that changes once, which is demonstrated to be applicable to the study of an undersaturated traffic signal. In the course of describing the usefulness of this technique for estimating several measures, including the maximum length of a physical queue and the time when this maximum occurs, the difference between “delay” at a bottleneck and the “time spent in queue,” which appears to have been confused in some of the literature, is clarified.

scholarly journals Research on the impact of ship traffic flow on the restricted channel segment of the middle Yangtze River based on traffic wave theory

2021 ◽  
Vol 3 (8) ◽  
Author(s):  
Ting Liu ◽  
Gabriel Lodewijks
Keyword(s):  
Traffic Flow ◽  
Flow Rate ◽  
Flow Simulation ◽  
Wave Theory ◽  
Flow Density ◽  
List Type ◽  
Ship Traffic ◽  
Traffic Wave ◽  
The Impact ◽  
Channel Segment

Abstract Abstract On the basis of the influence of dry season on ship traffic flow, the gathering and dissipating process of ship traffic flow was researched with Greenshields linear flow—density relationship model, the intrinsic relationship between the ship traffic congestion state and traffic wave in the unclosed restricted channel segment was emphatically explored when the ship traffic flow in a tributary channel inflows, and the influence law of multiple traffic waves on the ship traffic flow characteristics in unclosed restricted segment is revealed. On this basis, the expressions of traffic wave speed and direction, dissipation time of queued ships and the number of ships affected were provided, and combined with Monte Carlo method, the ship traffic flow simulation model in the restricted channel segment was built. The simulation results show that in closed restricted channel segment the dissipation time of ships queued is mainly related to the ship traffic flow rate of segments A and C, and the total number of ships affected to the ship traffic flow rate of segment A. And in unclosed restricted channel segment, the dissipation time and the total number of ships affected are also determined by the meeting time of the traffic waves in addition to the ship traffic flow rate of segments. The research results can provide the theoretical support for further studying the ship traffic flow in unclosed restricted channel segment with multiple tributaries Article Highlights The inflow of tributaries' ship traffic flows has an obvious impact on the traffic conditions in the unenclosed restricted channel segment. The interaction and influence between multiple ship traffic waves and the mechanism of generating new traffic waves are explained. The expression of both dissipation time of queued ships and the total number of ships affected in the closed and unclosed restricted channel segment are given.

scholarly journals Exact Boundary Controllability for Free Traffic Flow with Lipschitz Continuous State

2016 ◽  
Vol 2016 ◽  
pp. 1-11 ◽  
Author(s):  
Martin Gugat
Keyword(s):  
Traffic Flow ◽  
Control Function ◽  
Piecewise Linear ◽  
Lipschitz Constant ◽  
Initial Density ◽  
Free Flow ◽  
Flow Density ◽  
Initial State ◽  
Lipschitz Continuous ◽  
Continuous State

We consider traffic flow governed by the LWR model. We show that a Lipschitz continuous initial density with free-flow and sufficiently small Lipschitz constant can be controlled exactly to an arbitrary constant free-flow density in finite time by a piecewise linear boundary control function that controls the density at the inflow boundary if the outflow boundary is absorbing. Moreover, this can be done in such a way that the generated state is Lipschitz continuous. Since the target states need not be close to the initial state, our result is a global exact controllability result. The Lipschitz constant of the generated state can be made arbitrarily small if the Lipschitz constant of the initial density is sufficiently small and the control time is sufficiently long. This is motivated by the idea that finite or even small Lipschitz constants are desirable in traffic flow since they might help to decrease the speed variation and lead to safer traffic.

Influence of the Moving Bottleneck on the Traffic Flow on Expressway

2011 ◽  
Vol 97-98 ◽  
pp. 480-484 ◽  
Author(s):  
Qiao Ru Li ◽  
Yue Xiang Pan ◽  
Liang Chen ◽  
Chang Guang Cheng
Keyword(s):  
Traffic Flow ◽  
Wave Theory ◽  
Capacity Analysis ◽  
Kinematic Wave ◽  
Software Simulation ◽  
Low Speed ◽  
Traffic Capacity ◽  
Simulation Results

The mix rate of large trucks is extremely high on expressway in China. The influence of moving bottleneck on the traffic flow of the expressway is particularly serious. The moving bottleneck, formed due to the overtaking of the low-speed trucks, is analyzed with the kinematic wave theory and simulated by utilizing the VISSIM software. Simulation results indicate that increase of the traffic flow and the mix rate of trucks could aggravate the influence of the moving bottleneck on the traffic states, and decrease the speeds of cars significantly. This leads to the insufficient use of the expressway resources. The study result can contribute to the traffic capacity analysis of the expressway.

Kinematic wave theory of bottlenecks of varying capacity

1956 ◽  
Vol 52 (3) ◽  
pp. 564-572 ◽  
Author(s):  
S. C. De
Keyword(s):  
Shock Wave ◽  
Traffic Flow ◽  
Wave Velocity ◽  
Wave Theory ◽  
Kinematic Wave ◽  
Oncoming Flow ◽  
Unit Distance ◽  
Uniform Rate ◽  
Kinematic Waves ◽  
Flow Quantity

ABSTRACTThis paper discusses a problem in traffic flow by the method of kinematic waves developed by Lighthill and Whitham(1,2). The theory of kinematic waves introduced by Lighthill and Whitham has been extended here to include the case when the flow q varies with the time, and it is seen that the expression for the wave velocity is of the same form as before, namely, ∂q/∂k, where q is the flow (quantity passing a given point in unit time) and k is the concentration (quantity per unit distance). The theory is applied to the problem of estimating how a uniform oncoming flow behaves on entering a bottleneck, the capacity of which varies with time. This capacity has initially a higher value than the oncoming flow but falls at a uniform rate to a lower value, where it remains constant for a time, and again rises at a uniform rate to the original value. A shock wave is found to move back from the bottleneck, and later forward again and through it, much as in the case of a bottleneck of constant capacity with varying oncoming flow studied by Lighthill and Whitham.

scholarly journals An Eco-Friendly Multimodal Route Guidance System for Urban Areas Using Multi-Agent Technology

2021 ◽  
Vol 11 (5) ◽  
pp. 2057
Author(s):  
Abdallah Namoun ◽  
Ali Tufail ◽  
Nikolay Mehandjiev ◽  
Ahmed Alrehaili ◽  
Javad Akhlaghinia ◽  
...  
Keyword(s):  
Traffic Flow ◽  
Urban Areas ◽  
Urban Environments ◽  
Ease Of Use ◽  
Transport Infrastructure ◽  
Guidance System ◽  
Planning System ◽  
Flow Density ◽  
Route Guidance ◽  
Agent Based

The use and coordination of multiple modes of travel efficiently, although beneficial, remains an overarching challenge for urban cities. This paper implements a distributed architecture of an eco-friendly transport guidance system by employing the agent-based paradigm. The paradigm uses software agents to model and represent the complex transport infrastructure of urban environments, including roads, buses, trolleybuses, metros, trams, bicycles, and walking. The system exploits live traffic data (e.g., traffic flow, density, and CO2 emissions) collected from multiple data sources (e.g., road sensors and SCOOT) to provide multimodal route recommendations for travelers through a dedicated application. Moreover, the proposed system empowers the transport management authorities to monitor the traffic flow and conditions of a city in real-time through a dedicated web visualization. We exhibit the advantages of using different types of agents to represent the versatile nature of transport networks and realize the concept of smart transportation. Commuters are supplied with multimodal routes that endeavor to reduce travel times and transport carbon footprint. A technical simulation was executed using various parameters to demonstrate the scalability of our multimodal traffic management architecture. Subsequently, two real user trials were carried out in Nottingham (United Kingdom) and Sofia (Bulgaria) to show the practicality and ease of use of our multimodal travel information system in providing eco-friendly route guidance. Our validation results demonstrate the effectiveness of personalized multimodal route guidance in inducing a positive travel behavior change and the ability of the agent-based route planning system to scale to satisfy the requirements of traffic infrastructure in diverse urban environments.

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