scholarly journals Automatic calibration of fundamental diagram for first-order macroscopic freeway traffic models

2015 ◽  
Vol 50 (3) ◽  
pp. 363-385 ◽  
Author(s):  
Renxin Zhong ◽  
Changjia Chen ◽  
Andy H. F. Chow ◽  
Tianlu Pan ◽  
Fangfang Yuan ◽  
...  
Keyword(s):  
Automatic Calibration ◽  
Fundamental Diagram ◽  
Freeway Traffic ◽  
Traffic Models ◽  
First Order

scholarly journals THE EFFECT OF DELAY TIMES ON THE OPTIMAL VELOCITY TRAFFIC FLOW BEHAVIOR

2005 ◽  
Vol 16 (09) ◽  
pp. 1461-1471 ◽  
Author(s):  
H. EZ-ZAHRAOUY ◽  
Z. BENRIHANE ◽  
A. BENYOUSSEF
Keyword(s):  
Flow Behavior ◽  
Velocity Model ◽  
Traffic Patterns ◽  
Current Profile ◽  
Fundamental Diagram ◽  
Large Delay ◽  
Optimal Velocity ◽  
First Order ◽  
Small Delay ◽  
Delay Times

We have numerically investigated the effect of the delay times τf and τs of a mixture of fast and slow vehicles on the fundamental diagram (the current-density relation) of the optimal velocity model. The optimal velocity function of the fast cars depends not only on the headway of each car but also on the headway of the immediately preceding one. It is found that the small delay times have almost no effects, while, for sufficiently large delay time τs, the current profile displays qualitatively five different forms, depending on τf, τs and the fractions df and ds of the fast and slow cars, respectively. The velocity (current) exhibits first-order transitions at low and/or high densities, from freely moving phase to the congested state, and from congested state to a jamming one, respectively. The minimal current appears in intermediate values of τs. Furthermore, there exist a critical value of τf above which the metastability and hysteresis appear. The spatial-temporal traffic patterns near the congested-jamming first-order transition is also presented.

scholarly journals Estimating Macroscopic Volume Delay Functions with the Traffic Density Derived from Measured Speeds and Flows

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Rafał Kucharski ◽  
Arkadiusz Drabicki
Keyword(s):  
Traffic Congestion ◽  
Goodness Of Fit ◽  
Estimation Methods ◽  
Traffic Density ◽  
Fundamental Diagram ◽  
Traffic Models ◽  
Delay Function ◽  
Measured Time ◽  
Monotonically Decreasing Function ◽  
Macroscopic Volume

This paper proposes a new method to estimate the macroscopic volume delay function (VDF) from the point speed-flow measures. Contrary to typical VDF estimation methods it allows estimating speeds also for hypercritical traffic conditions, when both speeds and flow drop due to congestion (high density of traffic flow). We employ the well-known hydrodynamic relation of fundamental diagram to derive the so-called quasi-density from measured time-mean speeds and flows. This allows formulating the VDF estimation problem with a speed being monotonically decreasing function of quasi-density with a shape resembling the typical VDF like BPR. This way we can use the actually observed speeds and propose the macroscopic VDF realistically reproducing actual speeds also for hypercritical conditions. The proposed method is illustrated with half-year measurements from the induction loop system in city of Warsaw, which measured traffic flows and instantaneous speeds of over 5 million vehicles. Although the proposed method does not overcome the fundamental limitations of static macroscopic traffic models, which cannot represent dynamic traffic phenomena like queue, spillback, wave propagation, capacity drop, and so forth, we managed to improve the VDF goodness-of-fit fromR2of 27% to 72% most importantly also for hypercritical conditions. Thanks to this traffic congestion in macroscopic traffic models can be reproduced more realistically in line with empirical observations.

On Modeling and Verification of Agent-Based Traffic Simulation Properties in Alloy

2012 ◽  
Vol 4 (4) ◽  
pp. 38-60 ◽  
Author(s):  
Junia Valente ◽  
Frederico Araujo ◽  
Rym Z. Wenkstern
Keyword(s):  
Intelligent Transportation Systems ◽  
Large Scale ◽  
Traffic Simulation ◽  
Simulation Models ◽  
Intelligent Transportation ◽  
Transportation Systems ◽  
Agent Based ◽  
Traffic Models ◽  
First Order ◽  
New Generation

The advances in Intelligent Transportation Systems (ITS) call for a new generation of traffic simulation models that support connectivity and collaboration among simulated vehicles and traffic infrastructure. In this paper we introduce MATISSE, a complex, large scale agent-based framework for the modeling and simulation of ITS and discuss how Alloy, a modeling language based on set theory and first order logic, was used to specify, verify, and analyze MATISSE’s traffic models.

An Improved Freeway Traffic Model in a First Order Hybrid Petri Net Framework

2012 ◽  
Vol 45 (9) ◽  
pp. 364-369
Author(s):  
M.P. Fanti ◽  
G Iacobellis ◽  
A.M. Mangini ◽  
W. Ukovich
Keyword(s):  
Petri Net ◽  
Traffic Model ◽  
Freeway Traffic ◽  
First Order ◽  
Hybrid Petri Net ◽  
Net Framework
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