Capacity of shared-short lanes at unsignalized intersections

Wu, Ning

doi:10.1016/s0965-8564(98)00041-x

Cited by 23 publications

(36 citation statements)

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“…This method has been incorporated into a software packages widely known as RODEL (Crown [13] [20]). The detailed formula for entry flow is discussed by Wu [21,22]. The French Model is based on the work carried out by Louah [23] which was later incorporated into a model known as GIRABASE [24].…”

Section: International Roundabout Capacity Modelsmentioning

confidence: 99%

Analysis of roundabout capacity under high demand flows

Al-Madani

Saad²

2009

WIT Transactions on the Built Environment

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Estimation of the entry capacity of roundabouts greatly varies between one method and another in their input requirements, model complexity and estimate accuracy. Several available models for the capacity estimation at approach entries of the roundabouts are tested here and compared for high traffic demand condition. The estimated entry capacities along with the actual entry demand are then compared for various gathered circulating flows. Two models for capacity estimate are developed for triple circulating lanes by triple and dual entry lanes. Thirteen roundabouts in Bahrain are used for the models' development and for the comparison purposes between the various tested methods. The geometric data were gathered from the actual drawings, scaled aerial photographs and from the field. The necessary traffic data were gathered during peak periods. Substantial differences in estimating capacities were observed between the various available international methods. This makes the judgment of accepting or rejecting the estimated capacity difficult. The developed model fall well in between the tested international models and matched the actual data reasonably well. The methods with complicated input parameters and extensive equations, as aaSIDRA, UK RODEL, French and Indian methods, did not prove to be better than much simpler ones like Swiss or FHWA methods. The findings are quite essential for traffic planners in making judicious decisions regarding roundabouts' performance. There is a real need for a more consistent model for the capacity estimation of roundabouts.

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Section: International Roundabout Capacity Modelsmentioning

confidence: 99%

Analysis of roundabout capacity under high demand flows

Al-Madani

Saad²

2009

WIT Transactions on the Built Environment

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“…In the second case, driver number 3 has accepted the space, thereby vehicle number 3 does not prevent vehicle number 4 from queuing in the flared area. Flared intersections have been shown to result in increased capacity compared to corresponding one lane intersections Kyte et al (1996) and Wu (1997). The increase in capacity depends on the length of flare and if it is a left flare, mixed flare or right flare.…”

Section: Introductionmentioning

confidence: 99%

“…The increase in capacity depends on the length of flare and if it is a left flare, mixed flare or right flare. Wu (1997) estimated the capacity increase to between 6 % and 60 %, depending of the flare design.…”

Section: Introductionmentioning

confidence: 99%

A Model for Traffic Simulation of Flared Rural Road Intersections

Strömgren

Olstam

Tapani

2015

Transportation Research Procedia

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This paper presents a micro-simulation model that takes flared design of rural intersections into consideration. The intersection model is designed with input parameters that describe the geometric conditions of the flare. The behavior model includes both a traditional gap-acceptance sub-model and a passage model for modelling of vehicles’ possibility to pass other vehicles using the flare. The intersection model developed has been implemented in the traffic micro simulation model RuTSim. The gap-acceptance part of the model has been calibrated using data for stop and yield 3-way intersections. The validation was performed by using video recordings to calculate delay for the yield regulated intersection and time in queue and service time for the stop regulated intersection. The results from the validation simulations correspond well with the empirical validation data. The effect of the flare on delay has been studied by using 3 different intersection lay-outs and different levels of minor and major flow. The result shows that the delay is decreasing with increasing intersection radius

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“…The German model is derived from the Tanner and Wu capacity equation and has been introduced officially into the German Highway Capacity Manual in 2001 [26,27]. The detailed formula for entry flow is discussed by Wu [28,29]. The French model is based on the work carried out by Louah [30] which later was incorporated into a model known as GIRABASE [31].…”

Section: Introductionmentioning

confidence: 99%

“…At least two models are currently available in the recent US literature; the Highway Capacity Manual (HCM 2010) [4] and the Federal Highway Administration (FHWA) models [19,32]. According to Robinson and Rodegerdts [18] the FHWA model is based on Wu's model [28,29].…”

Section: Introductionmentioning

confidence: 99%

Calibration of international capacity models for dual lane roundabouts during saturation flow condition

Al-Madani¹

2012

WIT Transactions on the Built Environment

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Varying differences in the prediction of roundabout capacities were observed between various international models and field data. This study attempts to calibrate 7 international models for forced flow conditions. These include UK, aaSIDRA, Swiss, US FHWA, HCM, French and German models. These are compared with field data collected from 12 large roundabouts in Bahrain. They are compared considering scattered plots, Root Mean Square Error (RMSE) and t-tests. Each model is calibrated by a trial multiplicative factor which is then adjusted in an iterative manner until best match with actual data is achieved. The calibration adjusts the Y-intercept and the slope of each model. The calibration factors, based on the initial results, showed high variations in the adjustment factors between one model and another. The calibrated models showed substantial improvements and were fairly comparable with actual data. The UK, aaSIDRA and French models, with over 40% reduction, required the greatest adjustments to suite the field data. The FHWA model required 35% reduction and the German model required 15% increase to reasonably fit the field data. The HCM method required no adjustments and the Swiss model required a reduction of 5%. The calibration factors were as follows in respective order: 0.5225, 0.515, 0.585, 0.65, 1.16, 1.0 and 0.95. While differences in capacity prediction between one international model and another confuse the practitioners; calibrated models assist them to have just predictions regarding roundabout capacities during forced flow conditions. The developed calibrations require further investigation to reduce the deviation between the calibrated models and the actual data.

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Capacity of shared-short lanes at unsignalized intersections

Cited by 23 publications

References 0 publications

Analysis of roundabout capacity under high demand flows

Analysis of roundabout capacity under high demand flows

A Model for Traffic Simulation of Flared Rural Road Intersections

Calibration of international capacity models for dual lane roundabouts during saturation flow condition

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