Variations in Parameters of Time Headway Models According to Macroscopic Variables, Fundamental Diagram, and Exogenous Effects

Ha, Duy-Hung; Aron, Maurice; Cohen, Simon

doi:10.3141/2260-12

Cited by 8 publications

(4 citation statements)

References 14 publications

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“…where f, TH U, and TH V are the probability density functions of overall headway, following headway, and free headway, respectively, and t, θ, u, d, and µ are parameters of the functions. Gamma-GQM is a GQM that uses gamma distribution as the g function and can be represented as follows (5,6,18):…”

Section: Methodology Description Of Gqmmentioning

confidence: 99%

“…Time headway studies are carried out for a number of important reasons. This may include analysis of traffic safety, computation of highway capacity, study of drivers' car-following behavior, setting optimal variable speed limits, optimization of intersection signals, and generation of vehicles in microscopic traffic simulation (3)(4)(5). Also, the reciprocal of mean time headways is the hourly traffic flow rate, which makes it an important variable to a traffic engineer.…”

Section: Comparison Of Good and Adverse Weather Conditionsmentioning

confidence: 99%

“…However, they considered only light and medium rainfall intensities, because no data matching to heavy rain intensity were found. Ha et al (5) conducted another study on time headway distribution using gamma-GQM and tried to determine the relationship between this microscopic traffic variable and other macroscopic variables, such as volume, occupancy, and mean speed. The strength of their work is that they tried to interpret the variation of the four parameters of gamma-GQM, whereas the major flaw of their work was treating rain as a binary variable (yes/no) rather than segmenting it quantitatively based on its intensity.…”

Section: Literature Reviewmentioning

confidence: 99%

“…Simple models have difficulty in modeling short headways and limited capacity of modeling wider traffic scopes. On the contrary, GQM has proved to have good performance in modeling headways of different traffic contexts with a sound goodness of fit to headway histogram densities as shown by statistical tests of chi-squared and Kolmogorov-Smirnov (6,5,17,18). GQM has been shown to provide insight on the motorway traffic stream and driver behavior for various traffic conditions.…”

Section: Literature Reviewmentioning

confidence: 99%

See 3 more Smart Citations

Parameters of Time Headway Distribution as Performance Indicators of Motorway Traffic and Driver Behavior

Habtemichael¹,

Picado-Santos²,

Faouzi

2012

Transportation Research Record

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Together with the Federal Highway Administration, the South Dakota Local Technical Assistance Program published a manual on unpaved roads (3). This manual asks 10 questions to determine the real need to improve or change existing pavement and suggests the best type of road pavement.Smadi et al. summarize several research efforts that have examined alternative approaches to reduce gravel road maintenance costs (4). These potential solutions may generally be classified as• Modifying the gravel surface of high-traffic roads (i.e., paving or using chemical additives),• Reducing maintenance on gravel roads with low traffic volume, and• Closing unnecessary gravel roads.The decision as to which strategy to consider must be based on sound engineering, financial, and legal analysis. The authors illustrate how effective public involvement (user buy-in) is a key factor in the decision-making process. Rukashaza-Mukome et al. used data gathered from numerous Minnesota counties to investigate spending on low-volume road maintenance and claim that their data enabled county and local governments to make informed decisions about when it may be economically advantageous to upgrade and pave aggregate roads (5). The activities examined included maintenance grading, regraveling, dust control or stabilization, reconstruction or regrading, paving, and associated maintenance activities. The expected end product was a set of modifiable relationships to address local conditions, including the calculated cumulative maintenance cost per mile. These relationships are expected to show how the maintenance costs of aggregate, lightly surfaced, and hot-mix asphalt (HMA) roads vary by surface type, age, and traffic.Wolters et al. present a method based on a life-cycle cost analysis considering both agency costs and user costs (crash costs and vehicle operating costs only) in an analysis of four surface types (HMA, blotter, stabilized gravel, and gravel) from an economic point of view (6). Based on the default models developed from an analysis of agency costs only, the average daily traffic levels should be 0 to 150 vehicles/day for gravel, 150 to 660 vehicles/day for blotter, and more than 660 vehicles/day for HMA surfaces. The authors hold that the consideration of user costs and other noneconomic factors may affect decisions about which surface type is most appropriate for a given traffic level and may be taken into account using the method developed during this project. The use of the method is facilitated by using a manual process outlined in a standalone technical brief or an automated spreadsheet tool.Werkmeister and Alabaster present a practical method for estimating the remaining pavement life of LVRs that uses falling weight deflectometer (FWD) measurements (7). The method was developed For many years, much research has been carried out to assess the affordability of paving a road. Now, increased construction and maintenance costs for traditional asphalt pavement systems have persuaded many civil administrations, regional councils, and a...

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Section: Methodology Description Of Gqmmentioning

confidence: 99%

Section: Comparison Of Good and Adverse Weather Conditionsmentioning

confidence: 99%

Section: Literature Reviewmentioning

confidence: 99%

Section: Literature Reviewmentioning

confidence: 99%

See 2 more Smart Citations

Parameters of Time Headway Distribution as Performance Indicators of Motorway Traffic and Driver Behavior

Habtemichael¹,

Picado-Santos²,

Faouzi

2012

Transportation Research Record

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Gamma-GQM Time Headway Model: Endogenous Effects in Rural Two-lane Two-way Roads

Rossi

Gastaldi

Pascucci

2014

Procedia - Social and Behavioral Sciences

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Study of vehicle time headway distributions is essential in many traffic engineering applications, such as capacity and level of service analysis and, in recent years, in the fields of vehicle generation in traffic micro-simulation models and driving simulation applications. This paper presents results from an experimental analysis of vehicle time headway distributions on two-lane two-way rural roads. Analysis focused on estimating a well-known model, the gamma-generalized queuing model (gamma-GQM). A trendless analysis of observed time headways was also carried out. The endogenous traffic parameters considered as affecting time headway distributions were flow rate and flow composition (percentage of heavy vehicles). Exogenous conditions, such as weather and geometric futures, were common to all time periods and cross-sections analysed. Gamma-GQM pdf appears to be very suitable for representing real headway distributions in all the analysed situations; it fits real-time headway distributions well, despite flow rate range and traffic composition (range of percentage of heavy vehicles)

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Time headway variable and probabilistic modeling

Ha¹,

Aron

Cohen

2012

Transportation Research Part C: Emerging Technologies

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Variations in Parameters of Time Headway Models According to Macroscopic Variables, Fundamental Diagram, and Exogenous Effects

Cited by 8 publications

References 14 publications

Parameters of Time Headway Distribution as Performance Indicators of Motorway Traffic and Driver Behavior

Parameters of Time Headway Distribution as Performance Indicators of Motorway Traffic and Driver Behavior

Gamma-GQM Time Headway Model: Endogenous Effects in Rural Two-lane Two-way Roads

Time headway variable and probabilistic modeling

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