scholarly journals Estimation of gap acceptance parameters for HCM 2010 roundabout capacity model applications

2012 ◽  
Author(s):  
A. Gazzarri ◽  
M. T. Martello ◽  
A. Pratelli ◽  
R. R. Souleyrette
Keyword(s):  
Gap Acceptance ◽  
Capacity Model

Gap Acceptance Capacity Model for On-Ramp Junction of Urban Freeway

2009 ◽  
Vol 9 (4) ◽  
pp. 116-119 ◽  
Author(s):  
Yusheng CI ◽  
Lina WU ◽  
Yulong PEI ◽  
Xianzhang LING
Keyword(s):  
Gap Acceptance ◽  
Capacity Model ◽  
Urban Freeway

Capacity Modeling of Weaving Areas on Urban Expressways with Exclusive Bus Lanes Based on Gap Acceptance Theory

2019 ◽  
Vol 2673 (8) ◽  
pp. 365-376
Author(s):  
Xumei Chen ◽  
Xiaomi Han ◽  
Xianchao Jia ◽  
Lei Yu ◽  
Tao Wan
Keyword(s):  
General Purpose ◽  
Utilization Rate ◽  
Flow Ratio ◽  
Gap Acceptance ◽  
Lane Changing ◽  
Error Measures ◽  
Capacity Model ◽  
Bus Lane ◽  
Capacity Modeling ◽  
Gap Acceptance Theory

Intense lane-changing maneuvers at weaving sections often cause traffic turbulence on expressways, especially in the presence of a concurrent medium exclusive bus lane (XBL) and general purpose lanes. Such intense lane-changing activity usually affects the operation and reduces the capacity of weaving sections in relation to their equivalent basic expressway segments. In this context, a study on the capacity model of weaving areas on an expressway with a median XBL is conducted based on the analysis of lane-change behaviors using gap acceptance theory. Two weaving sections on expressways with median XBL are selected as case studies to obtain the estimated capacity as well as the maximum traffic throughput under a certain bus saturation on the XBL. The results show that estimated capacity is larger than maximum traffic throughput because of low utilization rate of buses on the XBL, and capacity is significantly affected by weaving demand. Error measures based on the estimated and observed maximum traffic throughput are analyzed to verify the validity of the proposed model. A sensitivity analysis shows that, compared with the increase of on-ramp bus flow ratio, the increase of off-ramp bus flow ratio results in a more obvious trend of the reduction of capacity and maximum traffic throughput.

Impact of Geometric Factors on the Capacity of Single-Lane Roundabouts

2018 ◽  
Vol 2672 (34) ◽  
pp. 10-19 ◽  
Author(s):  
Mark T. Johnson ◽  
Ting-Li Lin
Keyword(s):  
Geometric Model ◽  
Gap Acceptance ◽  
Highway Capacity ◽  
Aggregated Data ◽  
Highway Capacity Manual ◽  
Project Assessment ◽  
Capacity Model ◽  
Acceptance Model ◽  
Capacity Data ◽  
Geometric Variation

Roundabout capacity is primarily estimated by gap-acceptance or by geometric models. The 2010 Highway Capacity Manual (HCM 10) uses a gap-acceptance model developed by Siegloch with empirically derived values of critical gap and headway for single-lane and two-lane entries. A geometric capacity model was developed by Kimber and Hollis that diverged from gap-based models. The capacity of up to four lane entries was empirically derived from six geometric parameters. In 2012 capacity data were collected as part of the FHWA project, Assessment of Roundabout Capacity Models for the Highway Capacity Manual. These data were used to produce HCM6, an update of the HCM 2010. In HCM6, a capacity curve was fitted through all the capacity data for single-lane roundabouts. The large scatter of data about the mean capacity line suggests that the single-lane roundabouts may be separated into different geometric types to improve accuracy. To investigate this hypothesis, the capacity data were separated into two geometrically distinct types of single-lane roundabouts: smaller, compact and larger, curvilinear. The range of data for the disaggregated and aggregated data was compared. Also, a capacity line was derived for each type using the geometric capacity model and compared with the disaggregated data with the HCM6 method. The results demonstrate that differences in geometry, absent in HCM6, explain the wide data range. This was further confirmed by the geometric model that gave a good fit to both sets of data. These results indicate that the accuracy of capacity prediction is improved by including geometric variation.

scholarly journals ESTIMATING AND UPDATING GAP ACCEPTANCE PARAMETERS FOR HCM6TH ROUNDABOUT CAPACITY MODEL APPLICATIONS

2021 ◽  
Author(s):  
ANTONIO PRATELLI ◽  
LORENZO BROCCHINI ◽  
NICOLA FRANCESCONI
Keyword(s):  
Gap Acceptance ◽  
Capacity Model

Molecular Dynamics Using Non-Variational Polarizable Force Fields: Theory, Periodic Boundary Conditions Implementation and Application to the Bond Capacity Model

2019 ◽  
Author(s):  
Pier Paolo Poier ◽  
Louis Lagardere ◽  
Jean-Philip Piquemal ◽  
Frank Jensen
Keyword(s):  
Boundary Conditions ◽  
Periodic Boundary ◽  
Force Fields ◽  
Periodic Boundary Conditions ◽  
Computational Effort ◽  
Polarizable Force Fields ◽  
Energy Models ◽  
Capacity Model ◽  
Energy Gradient ◽  
Polarization Models

<div> <div> <div> <p>We extend the framework for polarizable force fields to include the case where the electrostatic multipoles are not determined by a variational minimization of the electrostatic energy. Such models formally require that the polarization response is calculated for all possible geometrical perturbations in order to obtain the energy gradient required for performing molecular dynamics simulations. </p><div> <div> <div> <p>By making use of a Lagrange formalism, however, this computational demanding task can be re- placed by solving a single equation similar to that for determining the electrostatic variables themselves. Using the recently proposed bond capacity model that describes molecular polarization at the charge-only level, we show that the energy gradient for non-variational energy models with periodic boundary conditions can be calculated with a computational effort similar to that for variational polarization models. The possibility of separating the equation for calculating the electrostatic variables from the energy expression depending on these variables without a large computational penalty provides flexibility in the design of new force fields. </p><div><div><div> </div> </div> </div> <p> </p><div> <div> <div> <p>variables themselves. Using the recently proposed bond capacity model that describes molecular polarization at the charge-only level, we show that the energy gradient for non-variational energy models with periodic boundary conditions can be calculated with a computational effort similar to that for variational polarization models. The possibility of separating the equation for calculating the electrostatic variables from the energy expression depending on these variables without a large computational penalty provides flexibility in the design of new force fields. </p> </div> </div> </div> </div> </div> </div> </div> </div> </div>

Distinguishing The Cognitive Processes Of Mindfulness: Developing A Standardised Mindfulness Technique For Use In Longitudinal Randomised Control Trials

2019 ◽  
Author(s):  
Ben Isbel ◽  
Mathew J Summers
Keyword(s):  
Cognitive Processes ◽  
Mindfulness Training ◽  
Mindfulness Practice ◽  
Explanatory Framework ◽  
Cognitive Faculty ◽  
Metacognitive Processes ◽  
Capacity Model ◽  
Developmental Progression ◽  
Open Monitoring ◽  
Randomised Control Trials

A capacity model of mindfulness is adopted to differentiate the cognitive faculty of mindfulness from the metacognitive processes required to cultivate this faculty in mindfulness training. The model provides an explanatory framework incorporating both the developmental progression from focussed attention to open monitoring styles of mindfulness practice, along with the development of equanimity and insight. A standardised technique for activating these processes without the addition of secondary components is then introduced. Mindfulness-based interventions currently available for use in randomised control trials introduce components ancillary to the cognitive processes of mindfulness, limiting their ability to draw clear causative inferences. The standardised technique presented here does not introduce such ancillary factors, rendering it a valuable tool with which to investigate the processes activated in this practice.

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