Variable speed limit control for steady and oscillatory queues at fixed freeway bottlenecks

Chen, Danjue; Ahn, Soyoung; Hegyi, Andreas

doi:10.1016/j.trb.2014.08.006

Cited by 77 publications

(43 citation statements)

References 27 publications

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“…Carlson et al (2011) also pointed out the potential for a vehicle-infrastructure integration (VII) system as a mean to slow down the equipped vehicle to control the mainstream flow in a way similar to VSL system. In a more recent study, Chen et al (2014) used the same principle of limiting inflow to the bottleneck using kinematic wave theory and realized significant delay saving using the principle.…”

Section: Literature Reviewmentioning

confidence: 99%

Variable speed limit: A microscopic analysis in a connected vehicle environment

Khondaker

Kattan

2015

Transportation Research Part C: Emerging Technologies

238

103

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a b s t r a c tThis paper presents a Variable Speed Limit (VSL) control algorithm for simultaneously maximizing the mobility, safety and environmental benefit in a Connected Vehicle environment. Development of Connected Vehicle (CV)/Autonomous Vehicle (AV) technology has the potential to provide essential data at the microscopic level to provide a better understanding of real-time driver behavior. This paper investigated a VSL control algorithm using a microscopic approach by focusing on individual driver's behavior (e.g., acceleration and deceleration) through the use of Model Predictive Control (MPC) approach. A multi-objective optimization function was formulated with the aim of finding a balanced trade-off among mobility, safety and sustainability. A microscopic traffic flow prediction model was used to calculate Total Travel Time (TTT); a surrogate safety measure Time To Collision (TTC) was used to measure instantaneous safety; and, a microscopic fuel consumption model (VT-Micro) was used to measure the environmental impact. Real-time driver's compliance to the posted speed limit was used to adjust the optimal speed limit values. A sensitivity analysis was conducted to compare the performance of the developed approach for different weights in the objective function and for two different percentages of CV. The results showed that with 100% penetration rate, the developed VSL approach outperformed the uncontrolled scenario consistently, resulting in up to 20% of total travel time reductions, 6-11% of safety improvements and 5-16% reduction in fuel consumptions. Our findings revealed that the scenario which optimized for safety alone, resulted in more optimum improvements as compared to the multi-criteria optimization. Thus, one can argue that in case of 100% penetration rates of CVs, optimizing for safety alone is enough to achieve simultaneous and optimum improvements in all measures. However, mixed results were obtained in case of lower % penetration rate which showed higher collision risk when optimizing for only mobility or fuel consumption. This indicates that with such % penetration rate, multi-criteria optimization is crucial to realize optimum and balanced benefits for the examined measures.

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Section: Literature Reviewmentioning

confidence: 99%

Variable speed limit: A microscopic analysis in a connected vehicle environment

Khondaker

Kattan

2015

Transportation Research Part C: Emerging Technologies

238

103

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“…Newer research was made by Chena et al (2014) [30] with variable speed limit control for steady and oscillatory queues at fixed freeway bottlenecks. Li et al (2015) [31] develop a procedure for determining the optimal variable speed limit (VSL) control strategy for reducing collision risks and injury severity on large-scale freeway segments.…”

Section: Overview Of Previous Researchmentioning

confidence: 99%

“…In case that the value of factor of average speed variation on the observed section assumes a considerable change, it can be concluded that there have been considerable changes in speed of individual vehicles which means that for some reason here was a significant acceleration or deceleration. The calculation to determine speed changes in the observed section according to Lee et al [30] is:…”

Section: Change In Average Traffic Flow Speedmentioning

confidence: 99%

“…The coefficient of lane change frequency shown by equation (1) (COVV) is not relevant for the type of motorways in the Republic of Croatia, since the overtaking lane is used for overtaking and not for driving. For this reason, the volume change in each lane used in the model of Lee et al [30] was not an appropriate way to determine the frequency of lane change (in this case overtaking frequency).…”

Section: Factor Of Overtaking Frequencymentioning

confidence: 99%

“…In accordance with the newly researched factors that affect traffic flow safety on the tested section, a mathematical model developed according to the Lee et al model [29,30,31] is given, which can be used for:…”

Section: Mathematical Form Of the Modelmentioning

confidence: 99%

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Real-time traffic safety management model on motorways

Huzjan¹,

Mandžuka

Kos

2017

Teh. vjesn.

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Original scientific paper The methodology that allows predicting the occurrence of traffic accidents on the motorway was studied and defined in this paper. On the basis of this assessment the implementation of active measures for reducing the probability of their actual occurrence is included. The intensity of traffic does not give a simple correlation with the number and the type of accidents, that relationship is more complex. Previous studies have been applied to motorways with six and more traffic lanes, and no studies have been carried out for four-lane motorways (with the driving and overtaking lane on one carriageway). This paper presents a new model for such motorways, the model is based on measuring values of parameters of traffic flow and external factors that affect the traffic flow. The degree of crash potential was brought to correlation with the existing statistical data on traffic accidents on the test section and traffic flow data. This model is important for experts to produce algorithms that manage variable message signs on highways. Keywords: crash potential factor; four-lane motorways; traffic flow; traffic safety management model; variable message signs Model stvarno-vremenskog upravljanja sigurnošću prometa na autocestamaIzvorni znanstveni članka U radu je istražena i definirana metodologija koja omogućuje predviđanje nastanka prometnih nesreća na autocesti. Na osnovu te procjene uključuje se provedba aktivnih mjera za smanjenje vjerojatnosti njihova stvarnog nastanka. Sam intenzitet prometa ne daje jednostavnu korelacijsku vezu s brojem i vrstom prometnih nesreća već je taj odnos mnogo složeniji. Dosadašnja istraživanja primjenjivana su za autoceste sa šest i više prometnih traka, odnosno nema istraživanja napravljenih za četverotračne autoceste. U radu je prikazan novi model za takve autoceste, a baziran je na mjerenju vrijednosti parametara prometnog toka te vanjskih čimbenika koji utječu na odvijanje prometnog toka. Stupanj opasnosti od nastanka nesreće doveden je u korelaciju s postojećim statističkim podacima o prometnim nesrećama na testnoj dionici i podataka o prometnom toku. Ovaj model značajan je za eksperte koji izrađuju algoritme koji upravljaju promjenjivim prometnim znakovima na autocestama.Ključne riječi: četverotračne autoceste; faktor opasnosti nastanka prometne nezgode; model upravljanja sigurnošću prometa; prometni tok; promjenljiva svjetlosna signalizacija

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Numerical optimal control method for shockwaves reduction at stationary bottlenecks

Strnad

Fijavž

Žura

2016

J of Advced Transportation

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The paper introduces an optimal control method for traffic management with variable speed limits. It consists of traffic flow dynamics prediction with a non-linearized Lighthill-Whitham-Richards macroscopic traffic flow model, introduction of a cost functional, which enables stable shockwaves optimization, and numerical implementation of the optimization process with differential evolution. The method overcomes the discretization issues and provides speed limits that are in general not limited to small number of successive discrete points, i.e. variable message signs locations, nor in rounded speed limits. Performance of the method is demonstrated on a case study, which shows promising reduction of the backward moving shockwave that occurs because of a stationary bottleneck. On differential evolution algorithmsTo handle such an expanded optimal control problem a computationally effective method for numerical optimization process is required. We employ differential evolution (DE) approach introduced by Storn and Price [30,31]. DE is an evolutionary algorithm technique that is best suited for numerical optimization problems and has been found useful in many real-world optimization problems in engineering (e.g.[32] and [33]).There are three control parameters in DE, namely the mutation factor or scale factor, F ∈ [0, 2], the crossover probability, CR ∈ [0, 1], and the population size, NP ≥ 4. The selection of these parameters 842 I. STRNAD ET AL.

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Variable speed limit control for steady and oscillatory queues at fixed freeway bottlenecks

Cited by 77 publications

References 27 publications

Variable speed limit: A microscopic analysis in a connected vehicle environment

Variable speed limit: A microscopic analysis in a connected vehicle environment

Real-time traffic safety management model on motorways

Numerical optimal control method for shockwaves reduction at stationary bottlenecks

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