scholarly journals Calibrating the Robertson’s Platoon Dispersion Model on a Coordinated Corridor with Advance Warning Flashers

2017 ◽  
Vol 2623 (1) ◽  
pp. 10-18
Author(s):  
Li Zhao ◽  
Laurence R. Rilett ◽  
Ernest Tufuor
Keyword(s):  
High Speed ◽  
Arrival Time ◽  
Dispersion Model ◽  
Urban Traffic ◽  
Smoothing Factor ◽  
Signal Coordination ◽  
Comparison Results ◽  
Time Coefficient ◽  
Dispersion Patterns ◽  
Platoon Dispersion

Platoon dispersion (PD) is the foundation of traffic signal coordination in an urban traffic network. PD describes the phenomenon by which vehicles depart from an upstream intersection as a platoon and begin to disperse before they arrive at the downstream intersection. Recently, advance warning flashers (AWFs) have been applied in many high-speed corridors. There is a need to update the traditional PD model to include the effect of AWFs. This paper examines the traffic flow dispersion patterns when an AWF is present and tests the hypothesis that the AWF will affect PD on a coordinated signal corridor. Platoon vehicles, which are not affected by the operation of the AWF, are used for comparison. Results show that when the AWF effect is included in the PD model, the smoothing factor F of the Robertson’s PD model ranges from 0.11 to 0.13. This range is smaller than the smoothing factor without the AWF effect. The platoon arrival time coefficient β ranges from 0.777 to 0.819 with the AWF effect. This is approximately the same as the default value of 0.8 in the TRANSYT simulation model. The PD coefficient α increases from an average of 0.11 with the AWF effect to an average of 0.24 without the AWF effect, which indicates an increase in roadway friction. It was concluded that AWFs increase the dispersion of the platoons, which might affect signal coordination.

Calibration of Platoon Dispersion Parameters on the Basis of Link Travel Time Statistics

2000 ◽  
Vol 1727 (1) ◽  
pp. 89-94 ◽  
Author(s):  
Lei Yu
Keyword(s):  
Travel Time ◽  
Traffic Management ◽  
Dispersion Model ◽  
Time Data ◽  
Dispersion Parameters ◽  
Smoothing Factor ◽  
Travel Time Data ◽  
Platoon Dispersion ◽  
Advanced Traffic Management System ◽  
Link Travel Time

A calibration technique for platoon dispersion parameters for the widely used TRANSYT platoon dispersion model is presented. This technique calibrates platoon dispersion factor, travel time factor, and smoothing factor directly from the average link travel time and its standard deviation and can capture practically all of the roadway and traffic conditions in the field such as road grades, curvature, parking, opposing flow interference, traffic volume, and other sources of impedance. The technique is especially suited for applications in advanced traffic management system networks in which the required link travel time data could be obtained on a real-time basis. TRANSYT’s implementation of two scenarios is examined. The first scenario inputs the calibrated platoon dispersion parameter, with the result being that the smoothing factor used by TRANSYT is different from the calibrated parameter. The second scenario inputs a revised platoon dispersion factor, which is designed to make the smoothing factor used by TRANSYT identical to the calibrated parameter. This examination induces a recommendation that the TRANSYT input card or its internal calculation procedure for platoon dispersion be revised so that the average link travel time in the geometric distributed platoon dispersion model is consistent with those from the same model. The calibration of platoon dispersion parameters with field-collected link travel time data shows that platoon dispersion parameters are different for different standard deviations of link travel times even on the same street, and, therefore, the platoon dispersion parameters must be calibrated on a site-specific basis.

scholarly journals Transit-Based Emergency Evacuation with Transit Signal Priority in Sudden-Onset Disaster

2016 ◽  
Vol 2016 ◽  
pp. 1-13 ◽  
Author(s):  
Ciyun Lin ◽  
Bowen Gong
Keyword(s):  
Arrival Time ◽  
Time Estimation ◽  
Emergency Evacuation ◽  
Sudden Onset ◽  
Traffic Signal ◽  
Traffic Signal Control ◽  
Transit Signal Priority ◽  
Signal Coordination ◽  
Arterial Traffic ◽  
Evacuation Route

This study presents methods of transit signal priority without transit-only lanes for a transit-based emergency evacuation in a sudden-onset disaster. Arterial priority signal coordination is optimized when a traffic signal control system provides priority signals for transit vehicles along an evacuation route. Transit signal priority is determined by “transit vehicle arrival time estimation,” “queuing vehicle dissipation time estimation,” “traffic signal status estimation,” “transit signal optimization,” and “arterial traffic signal coordination for transit vehicle in evacuation route.” It takes advantage of the large capacities of transit vehicles, reduces the evacuation time, and evacuates as many evacuees as possible. The proposed methods were tested on a simulation platform with Paramics V6.0. To evaluate and compare the performance of transit signal priority, three scenarios were simulated in the simulator. The results indicate that the methods of this study can reduce the travel times of transit vehicles along an evacuation route by 13% and 10%, improve the standard deviation of travel time by 16% and 46%, and decrease the average person delay at a signalized intersection by 22% and 17% when the traffic flow saturation along an evacuation route is0.8<V/C≤1.0andV/C>1.0, respectively.

scholarly journals Low-Complexity Hardware Interleaver/Deinterleaver for IEEE 802.11a/g/n WLAN

VLSI Design ◽  
2012 ◽  
Vol 2012 ◽  
pp. 1-7
Author(s):  
Zhen-dong Zhang ◽  
Bin Wu ◽  
Yu-mei Zhou ◽  
Xin Zhang
Keyword(s):  
High Speed ◽  
Critical Path ◽  
Low Complexity ◽  
Cmos Technology ◽  
Path Delay ◽  
Hardware Complexity ◽  
Ieee 802.11A ◽  
Comparison Results ◽  
Mathematical Formulas ◽  
High Flexibility

A high-speed low-complexity hardware interleaver/deinterleaver is presented. It supports all 77 802.11n high-throughput (HT) modulation and coding schemes (MCSs) with short and long guard intervals and the 8 non-HT MCSs defined in 802.11a/g. The paper proposes a design methodology that distributes the three permutations of an interleaver to both write address and read address. The methodology not only reduces the critical path delay but also facilitates the address generation. In addition, the complex mathematical formulas are replaced with optimized hardware structures in which hardware intensive dividers and multipliers are avoided. Using 0.13 um CMOS technology, the cell area of the proposed interleaver/deinterleaver is 0.07 mm2, and the synthesized maximal working frequency is 400 MHz. Comparison results show that it outperforms the three other similar works with respect to hardware complexity and max frequency while maintaining high flexibility.

scholarly journals GEOSTATISTICS FOR AIR QUALITY MAPPING: CASE OF BAGUIO CITY, PHILIPPINES

2019 ◽  
Vol XLII-4/W19 ◽  
pp. 353-359
Author(s):  
R. V. Ramos ◽  
A. C. Blanco
Keyword(s):  
Air Quality ◽  
Dispersion Model ◽  
Atmospheric Dispersion ◽  
Spatial Variations ◽  
Dispersion Modeling ◽  
Dispersion Models ◽  
Night Time ◽  
Smoothing Factor ◽  
Pollutant Concentrations ◽  
Atmospheric Dispersion Models

Abstract. Mapping of air quality are often based on ground measurements using gravimetric and air portable sensors, remote sensing methods and atmospheric dispersion models. In this study, Geographic Information Systems (GIS) and geostatistical techniques are employed to evaluate coarse particulate matter (PM10) concentrations observed in the Central Business District of Baguio City, Philippines. Baguio City has been reported as one of the most polluted cities in the country and several studies have already been conducted in monitoring its air quality. The datasets utilized in this study are based on hourly simulations from a Gaussian-based atmospheric dispersion model that considers the impacts of vehicular emissions. Dispersion modeling results, i.e., PM10 concentrations at 20-meter interval, show that high values range from 135 to 422 μg/mm3. The pollutant concentrations are evident within 40 meters from the roads. Spatial variations and PM10 estimates at unsampled locations are determined using Ordinary Kriging. Geostatistical modeling estimates are evaluated based on recommended values for mean error (ME), root mean square error (RMSE) and standardized errors. Optimal predictors for pollutant concentrations at 5-meter interval include 2 to 5 search neighbors and variable smoothing factor for night-time datasets while 2 to 10 search neighbors and smoothing factors 0.3 to 0.5 were used for daytime datasets. Results from several interpolation tests indicate small ME (0.0003 to 0.0008 μg/m3) and average standardized errors (4.24 to 8.67 μg/m3). RMSE ranged from 2.95 to 5.43 μg/m3, which are approximately 2 to 3% of the maximum pollutant concentrations in the area. The methodology presented in this paper may be integrated with atmospheric dispersion models in refining estimates of pollutant concentrations, in generating surface representations, and in understanding the spatial variations of the outputs from the model simulations.

Traffic Platoon Dispersion Modeling on Arterial Streets

1996 ◽  
Vol 1566 (1) ◽  
pp. 49-53 ◽  
Author(s):  
Abdelaziz Manar ◽  
Karsten G. Baass
Keyword(s):  
Simulation Models ◽  
Traffic Signals ◽  
External Friction ◽  
Dispersion Modeling ◽  
Arterial Streets ◽  
Signal Coordination ◽  
Traffic Volumes ◽  
Platoon Dispersion ◽  
The City ◽  
Maximal Capacity

Platoon dispersion is a key element in traffic simulation models designed to measure arrivals at traffic signals. One of the most popular models is contained in the TRANSYT program. In this program, dispersion is defined by the platoon dispersion factor, which is given for three types of conditions in relation to external friction. This study demonstrates that platoon dispersion depends not only on external friction but also on internal friction between vehicles in the platoon. As volumes and densities increase, platoon dispersion increases up to a maximum, which is attained at half the capacity. As volumes and densities increase further, dispersion decreases and reaches a minimum value at volumes around maximal capacity. Experimental analysis on eight arterial sites in the city of Montreal (Quebec, Canada) has confirmed this relationship between dispersion and traffic volumes. Mathematical models (having a parabolic shape) relating platoon dispersion to internal and external friction were developed for three different categories of arterial streets representing low, moderate, and heavy friction levels. These models could be introduced into signal coordination programs and could contribute to a better simulation of arriving platoons at intersections as volumes change in relation to time.

scholarly journals Effects of ice particles shattering on the 2D-S probe

2011 ◽  
Vol 4 (7) ◽  
pp. 1361-1381 ◽  
Author(s):  
R. P. Lawson
Keyword(s):  
Particle Size ◽  
High Speed ◽  
Arrival Time ◽  
Primary Source ◽  
Time Algorithm ◽  
Post Processing ◽  
Cloud Particle ◽  
Ice Particles ◽  
Field Campaigns ◽  
Processing Techniques

Abstract. Recently, considerable attention has been focused on the issue of large ice particles shattering on the inlets and tips of cloud particle probes, which produces copious ice particles that can be mistakenly measured as real ice particles. Currently two approaches are being used to mitigate the problem: (1) Based on recent high-speed video in icing tunnels, probe tips have been designed that reduce the number of shattered particles that reach the probe sample volume, and (2) Post processing techniques such as image processing and using the arrival time of each individual particle. This paper focuses on exposing suspected errors in measurements of ice particle size distributions due to shattering, and evaluation of the two techniques used to reduce the errors. Data from 2D-S probes constitute the primary source of the investigation, however, when available comparisons with 2D-C and CIP measurements are also included. Korolev et al. (2010b) report results from a recent field campaign (AIIE) and conclude that modified probe tips are more effective than an arrival time algorithm when applied to 2D-C and CIP measurements. Analysis of 2D-S data from the AIIE and SPARTICUS field campaigns shows that modified probe tips significantly reduce the number of shattered particles, but that a particle arrival time algorithm is more effective than the probe tips designed to reduce shattering. A large dataset of 2D-S measurements with and without modified probe tips was not available from the AIEE and SPARTICUS field campaigns. Instead, measurements in regions with large ice particles are presented to show that shattering on the 2D-S with modified probe tips produces large quantities of small particles that are likely produced by shattering. Also, when an arrival time algorithm is applied to the 2D-S data, the results show that it is more effective than the modified probe tips in reducing the number of small (shattered) particles. Recent results from SPARTICUS and MACPEX show that 2D-S ice particle concentration measurements are more consistent with physical arguments and numerical simulations than measurements with older cloud probes from previous field campaigns. The analysis techniques in this paper can also be used to estimate an upper bound for the effects of shattering. For example, the additional spurious concentration of small ice particles can be measured as a function of the mass concentration of large ice particles. The analysis provides estimates of upper bounds on the concentration of natural ice, and on the remaining concentration of shattered ice particles after application of the post-processing techniques. However, a comprehensive investigation of shattering is required to quantify effects that arise from the multiple degrees of freedom associated with this process, including different cloud environments, probe geometries, airspeed, angle of attack, particle size and type.

The Study of Train Operation Plan of Night Train on Beijing-Guangzhou High-Speed Railway under Segmented Rectangular Maintenance Time Window

2014 ◽  
Vol 505-506 ◽  
pp. 619-623
Author(s):  
Hao Jia ◽  
Bao Ming Han ◽  
Qi Zhang
Keyword(s):  
Waiting Time ◽  
High Speed ◽  
Arrival Time ◽  
Time Window ◽  
High Speed Railway ◽  
Maintenance Time ◽  
Train Operation

Considering the demand of night train on Beijing-Guangzhou high-speed railway, two modes of segmented rectangular maintenance time window are discussed. Methods to make train operation plans under these two modes are proposed, aiming at shortening the train waiting time and making the departure and arrival time more reasonable. Comparing the new designed train operation plans with the original one under the vertical rectangular maintenance time window, it shows that segmented rectangular maintenance time window is better in night train operation.

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