A microsimulation approach to evaluate operations of weaving sections at urban unconventional intersections in Cairo

Abstract EN

Unconventional median U-turn intersections intersection treatments have been extensively implemented along major corridors in Cairo,, Egypt.

These unconventional treatments intersections do not involve signalization ve any signal control at any point, theypoint.

They utilize a non-traversable median with a U-turn crossover at the downstream to manage all crossing movements, thus movements and thus, creating a two-sided weaving sections between the minor approach and the U-turn crossoverbetween the minor approach and the Uturn slot on both sides of the median.

In.

In this paper, VISSIM is was used to model and simulate these weaving sections throughout an experimental analysis with with 4 main influential factors namely;; major demand, minor demand, weaving length andlength, and the minor through traffic splitsplit (% Mi THR).

The experimental design resulted in 960 scenarios whichscenario runs, which were simulated automated using through an external Visual Basic program developed specifically for this studyy.

Various programs were also developed for the simulation output extraction and manipulation.

The first stage o analysis was dedicatedwas dedicated to estimate the capacities of to estimate the capacities of the weaving sections and the minor entrance whichentrance, which were found to have a negatively correlation correlated.

with each other.Increasing the major demand caused a decrease in the minor entrance capacity and an increase in the capacities of the weaving Itsections.

It was also found that increasing capacities increase with the increase inthe weaving length ; however, increasing the length beyond 200 meters was not beneficial.

Increasing the minor through split caused an increase in volume ratio and a decrease in capacities Furthermore.

Furthermore, regression analysis was used to develop, various simulation based capacity prediction models that resulted in a relatively high R2 values.

The second stage of the analysis covered was dedicated to thetest the application appropriateness of the HCM 2010 weaving methodology to when applied to the urban weaving sections to predict capacities, lane change rates, and speedscompute capacities, lane change rates, weaving and non-weaving speeds for each weaving section.

Comparisons between the predicted and the simulated estimates with the simulation models sshowed that HCM the HCM 2010 2010 methodology provides provided higher extremely highcapacity predictions up to 1.6 times the capacity estimates almost double the simulated capacitiescapacities.

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The HCM 2010 also provided lower capacities for higher weaving lengths, which indicated a higher sensitivity to the increase in volume ratio and a lower sensitivity to the increase in weaving length .On the other hand, Thethe developed regression models on the other hand provided produced capacity more accurate estimationsestimations that were more realistic.

This provided evidence that the structure of the developed models were is more suited to represent capacities of similar weaving configurations.

Further comparisons using paired ttests and parity plots between the simulated and the predicted estimates showed that, HCM 2010the HCM 2010 methodology also underpredicted the lane change rates in the weaving sectionrates; s and thereby therefore, producing higher speed predictions were higher than the simulated speeds estimatesat each weaving section.

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FinallyFinally, an effort is was undertaken carried out to calibrate and modify the speed prediction algorithms of the HCM 2010 2010speed prediction algorithms using the simulation data points,; however, the effort did not produce yield any significant results.