Development of Pedestrian Recall Versus Actuation Guidelines for Pedestrian Crossings at Signalized Intersections

2021 ◽  
pp. 036119812110028
Author(s):  
Burak Cesme ◽  
Peter G. Furth ◽  
Ryan Casburn ◽  
Kevin Lee
Keyword(s):  
Cycle Length ◽  
Operational Efficiency ◽  
Signalized Intersections ◽  
Fairfax County ◽  
Time Duration ◽  
Real Network ◽  
Moderate Reduction ◽  
Cycle Lengths ◽  
Pedestrian Crossing ◽  
The Impact

At signalized intersections, pedestrian phases can be configured as recall or pushbutton actuated. While pedestrian recall results in a moderate reduction in pedestrian delay because, with recall, a pedestrian arriving during the time nominally reserved for the Walk interval will be served immediately rather than waiting to be served in the next cycle, it can also lead to longer cycle lengths, increasing delay for all users, including pedestrians. This research explores the impact of pedestrian recall along a coordinated-actuated arterial for pedestrians crossing the mainline (i.e., crossing the coordinated phase) to provide pedestrian recall versus actuation guidelines for agencies. The guidance was developed with the aim of balancing pedestrian delay with operational efficiency for vehicles. Two criteria were considered while developing the guidance: (1) pedestrian demand; and (2) vehicular green time duration for the concurrent vehicle phase that is parallel to the pedestrian crossing. VISSIM microsimulation software was used on a real network in Fairfax County, Virginia to model the effects of pedestrian recall and actuation. Results showed that pedestrian recall should be considered when pedestrian demand is large enough that there is a pedestrian call in most cycles (pedestrian probability in a given cycle is greater than 0.6 or pedestrian volume per cycle is greater than 0.9). The guidance also suggests setting pedestrian phases on recall when the length of the vehicular green for the concurrent phase is long enough in most cycles that a pedestrian phase would fit without constraining the signal cycle length.

Operational Effects of the Consolidated Intersection Design on Urban and Suburban Arterials

2018 ◽  
Vol 2672 (17) ◽  
pp. 96-107
Author(s):  
Daniel J. Cook
Keyword(s):  
Travel Time ◽  
Signalized Intersections ◽  
Signal Timing ◽  
Left Turn ◽  
Vehicle Delay ◽  
Cycle Lengths ◽  
Expected Benefits ◽  
Traffic Signal Timing ◽  
Critical Phases ◽  
Pedestrian Crossing

Along urban and suburban arterials, closely-spaced signalized intersections are commonly used to provide access to adjacent commercial developments. Often, these signalized intersections are designed to provide full access to developments on both sides of the arterial and permit through, left-turn, and right-turn movements from every intersection approach. Traffic signal timing is optimized to reduce vehicle delay or provide progression to vehicles on the arterial, or both. However, meeting both of these criteria can be cumbersome, if not impossible, under high-demand situations. This research proposes a new design that consolidates common movements at three consecutive signalized intersections into strategic fixed locations along the arterial. The consolidation of common movements allows the intersections to cycle between only two critical phases, which, in turn, promotes shorter cycle lengths, lower delay, and better progression. This research tested the consolidated intersection concept by modeling a real-world site in microsimulation software and obtaining values for delay and travel time for multiple vehicle paths along the corridor and adjacent commercial developments in both existing and proposed conditions. With the exception of unsignalized right turns at the periphery of the study area, all non-displaced routes showed a reduction in travel time and delay. Additional research is needed to understand how additional travel through the commercial developments adjacent to the arterial may effect travel time and delay. Other expected benefits of the proposed design include a major reduction in conflict points, shorter pedestrian crossing and wait times, and the opportunity to provide pedestrian refuge areas in the median.

Impact of Phase Sequence on Cycle Length Resonance

2019 ◽  
Vol 2673 (11) ◽  
pp. 398-408
Author(s):  
Christopher M. Day ◽  
A. M. Tahsin Emtenan
Keyword(s):  
Cycle Length ◽  
Strong Impact ◽  
Optimization Strategy ◽  
Sequence Optimization ◽  
Substantial Impact ◽  
Phase Sequence ◽  
Cycle Lengths ◽  
Potential Strategy ◽  
The Impact ◽  
Selection Of

The concept of resonant cycle length, that there are certain cycle lengths that may provide excellent progression owing to corridor geometry and other factors, has some currency as a potential strategy for cycle length selection. Past studies have identified resonant cycles under certain conditions and demonstrated benefits from use of the strategy as a means of selecting cycle length. The present study revisited the concept in application to flow-based models of traffic signal performance, highlighting the impact of phase sequence optimization. The phenomenon of cycle length resonance was explored for corridors with equal and randomly generated spacing between intersections, and finally for a field-calibrated corridor. Under each scenario, the performance of different cycle lengths was explored under two optimization strategies: optimization of only offsets, and optimization of both offsets and phase sequence. It was found that phase sequence has a substantial impact on the performance of coordination. Optimized phase sequences were found to yield 8% to 14% improvement in performance compared with use of the default sequence. For corridors where a resonant cycle length was evident, when phase sequences could also be adjusted, the poorer performance of non-resonant cycle lengths could be mitigated by optimizing phase sequence. Although use of a resonant cycle length is likely to yield good performance for some corridors under appropriate conditions, the use of a phase sequence optimization strategy is likely to have a strong impact on most corridors, and could be more impactful than selection of a resonant cycle length.

scholarly journals Development of an Optimization Traffic Signal Cycle Length Model for Signalized Intersections in China

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Yao Wu ◽  
Jian Lu ◽  
Hong Chen ◽  
Haifei Yang
Keyword(s):  
Delay Time ◽  
Cycle Length ◽  
Primary Objective ◽  
Signalized Intersections ◽  
Traffic Signal ◽  
Delay Model ◽  
Traffic Conditions ◽  
Vehicle Delay ◽  
Pedestrian Crossing ◽  
Xi’An City

The primary objective of this study is to develop an optimization traffic signal cycle length model for signalized intersections. Traffic data were collected from 50 signalized intersections in Xi’an city. Using comprehensive delay data, the optimization cycle length model is re-recalibrated to the Chinese traffic conditions based on the Webster delay model. The result showed that the optimization cycle length model takes vehicle delay time, pedestrian crossing time, and drivers’ anxiety into consideration. To evaluate the effects of the optimization cycle length model, three intersections were selected for a simulation. The delay time and queue length based on the optimization cycle length model and the TRRL model were compared. It was found that the delay times and queue lengths with the optimization cycle length model were significantly smaller than those with the TRRL model. The results suggested that the optimization traffic signal cycle length model was more optimal than the TRRL model.

Slow rate during AF improves ventricular performance by reducing sensitivity to cycle length irregularity

2002 ◽  
Vol 283 (6) ◽  
pp. H2706-H2713 ◽  
Author(s):  
Zoran B. Popović ◽  
Kent A. Mowrey ◽  
Youhua Zhang ◽  
Shaowei Zhuang ◽  
Tomotsugu Tabata ◽  
...  
Keyword(s):  
Cycle Length ◽  
Left Ventricular ◽  
Ventricular Performance ◽  
Nonlinear Fitting ◽  
Beneficial Effects ◽  
Sinus Cycle Length ◽  
Cycle Lengths ◽  
Anesthetized Dogs ◽  
Heart Rate Slowing ◽  
The Impact

Atrial fibrillation (AF) is characterized by short and irregular ventricular cycle lengths (VCL). While the beneficial effects of heart rate slowing (i.e., the prolongation of VCL) in AF are well recognized, little is known about the impact of irregularity. In 10 anesthetized dogs, R-R intervals, left ventricular (LV) pressure, and aortic flow were collected for >500 beats during fast AF and when the average VCL was prolonged to 75%, 100%, and 125% of the intrinsic sinus cycle length by selective atrioventricular (AV) nodal vagal stimulation. We used the ratio of the preceding and prepreceding R-R intervals (RRp/RRpp) as an index of cycle length irregularity and assessed its effects on the maximum LV power, the minimum of the first derivative of LV pressure, and the time constant of relaxation by using nonlinear fitting with monoexponential functions. During prolongation of VCL, there was a pronounced decrease in curvature with the formation of a plateau, indicating a lesser dependence on RRp/RRpp. We conclude that prolongation of the VCL during AF reduces the sensitivity of the LV performance parameters to irregularity.

scholarly journals A random cycle length approach for assessment of myocardial contraction in isolated rabbit myocardium

2009 ◽  
Vol 297 (5) ◽  
pp. H1940-H1948 ◽  
Author(s):  
Kenneth D. Varian ◽  
Ying Xu ◽  
Carlos A. A. Torres ◽  
Michelle M. Monasky ◽  
Paul M. L. Janssen
Keyword(s):  
Steady State ◽  
Cycle Length ◽  
Relaxation Times ◽  
Myocardial Contraction ◽  
Cardiac Contraction ◽  
Force Frequency ◽  
Cycle Lengths ◽  
Length Changes ◽  
Primary Cycle ◽  
The Impact

It is well known that the strength of cardiac contraction is dependent on the cycle length, evidenced by the force-frequency relationship (FFR) and the existence of postrest potentiation (PRP). Because the contractile strength of the steady-state FFR and force-interval relationship involve instant intrinsic responses to cycle length as well as slower acting components such as posttranslational modification-based mechanisms, it remains unclear how cycle length intrinsically affects cardiac contraction and relaxation. To dissect the impact of cycle length changes from slower acting signaling components associated with persisting changes in cycle length, we developed a novel technique/protocol to study cycle length-dependent effects on cardiac function; twitch contractions of right ventricular rabbit trabeculae at different cycle lengths were randomized around a steady-state frequency. Patterns of cycle lengths that resulted in changes in force and/or relaxation times can now be identified and analyzed. Using this novel protocol, taking under 10 min to complete, we found that the duration of the cycle length before a twitch contraction (“primary” cycle length) positively correlated with force. In sharp contrast, the cycle length one (“secondary”) or two (“tertiary”) beats before the analyzed twitch correlated negatively with force. Using this protocol, we can quantify the intrinsic effect of cycle length on contractile strength while avoiding rundown and lengthiness that are often complications of FFR and PRP assessments. The data show that the history of up to three cycle lengths before a contraction influences myocardial contractility and that primary cycle length affects cardiac twitch dynamics in the opposite direction from secondary/tertiary cycle lengths.

Income Diversification and Bank Efficiency in Vietnam

2017 ◽  
pp. 52-67
Author(s):  
Sang Nguyen Minh
Keyword(s):  
Regression Model ◽  
Commercial Banks ◽  
Banking System ◽  
Operational Efficiency ◽  
Commercial Banking ◽  
Tobit Regression ◽  
Income Diversification ◽  
Positive Effects ◽  
Study Results ◽  
The Impact

This study uses the DEA (Data Envelopment Analysis) method to estimate the technical efficiency index of 34 Vietnamese commercial banks in the period 2007-2015, and then it analyzes the impact of income diversification on the operational efficiency of Vietnamese commercial banks through a censored regression model - the Tobit regression model. Research results indicate that income diversification has positive effects on the operational efficiency of Vietnamese commercial banks in the research period. Based on study results, in this research some recommendations forpolicy are given to enhance the operational efficiency of Vietnam’s commercial banking system.

scholarly journals Impacts of mobile phone distractions on pedestrian crossing behavior at signalized intersections: An observational study in China

2019 ◽  
Vol 11 (4) ◽  
pp. 168781401984183 ◽  
Author(s):  
Zhuping Zhou ◽  
Sixian Liu ◽  
Wenxin Xu ◽  
Ziyuan Pu ◽  
Shuichao Zhang ◽  
...  
Keyword(s):  
Observational Study ◽  
Mobile Phone ◽  
Signalized Intersections ◽  
Pedestrian Crossing

Modeling Capacity of Through Movement at Signalized Intersection Affected by Short Left-Turn Bay under Different Signal Settings

2021 ◽  
pp. 036119812110064
Author(s):  
Zihang Wei ◽  
Yunlong Zhang ◽  
Xiaoyu Guo ◽  
Xin Zhang
Keyword(s):  
Cycle Length ◽  
Signalized Intersections ◽  
Signalized Intersection ◽  
Essential Factor ◽  
Highway Capacity ◽  
Left Turn ◽  
Highway Capacity Manual ◽  
Proposed Model ◽  
Vehicle Demand ◽  
The One

Through movement capacity is an essential factor used to reflect intersection performance, especially for signalized intersections, where a large proportion of vehicle demand is making through movements. Generally, left-turn spillback is considered a key contributor to affect through movement capacity, and blockage to the left-turn bay is known to decrease left-turn capacity. Previous studies have focused primarily on estimating the through movement capacity under a lagging protected only left-turn (lagging POLT) signal setting, as a left-turn spillback is more likely to happen under such a condition. However, previous studies contained assumptions (e.g., omit spillback), or were dedicated to one specific signal setting. Therefore, in this study, through movement capacity models based on probabilistic modeling of spillback and blockage scenarios are established under four different signal settings (i.e., leading protected only left-turn [leading POLT], lagging left-turn, protected plus permitted left-turn, and permitted plus protected left-turn). Through microscopic simulations, the proposed models are validated, and compared with existing capacity models and the one in the Highway Capacity Manual (HCM). The results of the comparisons demonstrate that the proposed models achieved significant advantages over all the other models and obtained high accuracies in all signal settings. Each proposed model for a given signal setting maintains consistent accuracy across various left-turn bay lengths. The proposed models of this study have the potential to serve as useful tools, for practicing transportation engineers, when determining the appropriate length of a left-turn bay with the consideration of spillback and blockage, and the adequate cycle length with a given bay length.

scholarly journals Reciprocal hemizygosity analysis reveals that the Saccharomyces cerevisiae CGI121 gene affects lag time duration in synthetic grape must

2021 ◽  
Author(s):  
Runze Li ◽  
Rebecca C Deed
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Low Temperatures ◽  
Lag Time ◽  
Lag Phase ◽  
Phenotypic Traits ◽  
Time Duration ◽  
Phase Duration ◽  
Grape Must ◽  
The Impact ◽  
Reciprocal Hemizygosity Analysis

Abstract It is standard practice to ferment white wines at low temperatures (10-18 °C). However, low temperatures increase fermentation duration and risk of problem ferments, leading to significant costs. The lag duration at fermentation initiation is heavily impacted by temperature; therefore, identification of Saccharomyces cerevisiae genes influencing fermentation kinetics is of interest for winemaking. We selected 28 S. cerevisiae BY4743 single deletants, from a prior list of open reading frames (ORFs) mapped to quantitative trait loci (QTLs) on chromosomes VII and XIII, influencing the duration of fermentative lag time. Five BY4743 deletants, Δapt1, Δcgi121, Δclb6, Δrps17a, and Δvma21, differed significantly in their fermentative lag duration compared to BY4743 in synthetic grape must (SGM) at 15 °C, over 72 h. Fermentation at 12.5 °C for 528 h confirmed the longer lag times of BY4743 Δcgi121, Δrps17a, and Δvma21. These three candidate ORFs were deleted in S. cerevisiae RM11-1a and S288C to perform single reciprocal hemizygosity analysis (RHA). RHA hybrids and single deletants of RM11-1a and S288C were fermented at 12.5 °C in SGM and lag time measurements confirmed that the S288C allele of CGI121 on chromosome XIII, encoding a component of the EKC/KEOPS complex, increased fermentative lag phase duration. Nucleotide sequences of RM11-1a and S288C CGI121 alleles differed by only one synonymous nucleotide, suggesting that intron splicing, codon bias, or positional effects might be responsible for the impact on lag phase duration. This research demonstrates a new role of CGI121 and highlights the applicability of QTL analysis for investigating complex phenotypic traits in yeast.

Impact of Turning Lane Storage Length and Turning Proportions on Throughput at Oversaturated Signalized Intersections

2021 ◽  
pp. 036119812110171
Author(s):  
A. M. Tahsin Emtenan ◽  
Christopher M. Day
Keyword(s):  
Flow Rate ◽  
Cycle Length ◽  
Signal Timing ◽  
Real World Data ◽  
Left Turn ◽  
Common Response ◽  
Cycle Lengths ◽  
Saturation Flow Rate ◽  
Saturation Flow ◽  
Timing Strategies

During oversaturated conditions, common objectives of signal timing are to maximize vehicle throughput and manage queues. A common response to increases in vehicle volumes is to increase the cycle length. Because the clearance intervals are displayed less frequently with longer cycle lengths and fewer cycles, more of the total time is used for green indications, which implies that the signal timing is more efficient. However, previous studies have shown that throughput reaches a peak at a moderate cycle length and extending the cycle length beyond this actually decreases the total throughput. Part of the reason for this is that spillback caused by the turning traffic may cause starvation of the through lanes resulting in a reduction of the saturation flow rate within each lane. Gaps created by the turning traffic after a lane change may also reduce the saturation flow rate. There is a relationship between the proportions of turning traffic, the storage length of turning lanes, and the total throughput that can be achieved on an approach for a given cycle length and green time. This study seeks to explore this relationship to yield better signal timing strategies for oversaturated operations. A microsimulation model of an oversaturated left-turn movement with varying storage lengths and turning proportions is used to determine these relationships and establish a mathematical model of throughput as a function of the duration of green, storage length, and turning proportion. The model outcomes are compared against real-world data.

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