Investigation of models for relating roundabout safety to predicted speed

Chen, Yongsheng; Persaud, Bhagwant; Sacchi, Emanuele; Bassani, Marco

doi:10.1016/j.aap.2012.04.011

Cited by 46 publications

(32 citation statements)

References 2 publications

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“…Finally, the negative sign associated with the proportion of heavy vehicles suggests that the speed decreases with the increase of the proportion of heavy vehicles since heavy vehicles usually move at lower speeds when negotiating roundabouts [2,22,38]. The values associated with the coefficients of determination ( 2 ) shown in Table 3 are mainly comparable with those found in similar prior research studies [1,22,39,40].…”

Section: Speed Prediction Modelssupporting

confidence: 78%

Predicting Operating Speeds at Urban Multilane Roundabouts in Abu Dhabi, United Arab Emirates

Almoarawi

Dabbour

2018

Journal of Advanced Transportation

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There are more than 460 multilane roundabouts located in Abu Dhabi, the capital city of the United Arab Emirates, and its surrounding areas. Most of those roundabouts have three entry/circulatory/exit lanes with large radii, which resulted in the majority of drivers exceeding the speed limits for those roundabouts. Those excessive operating speeds, along with lack of drivers' awareness of the proper rules of driving at roundabouts, have resulted in increased collision frequencies at Abu Dhabi roundabouts. In this paper, operating speeds were measured at 12 roundabouts in Abu Dhabi and those collected speed observations were used to calibrate regression models to predict the 85th percentile operating speeds at roundabouts in Abu Dhabi. Predicting operating speed at a roundabout, during its design stage, is necessary to ensure that the expected operating speed and capacity will meet the design expectations. Three models were calibrated to predict the entry, circulating, and exit speeds, respectively. The calibrated models were validated with data not used in calibration and they were found to be stable and robust. The findings of this research study will help engineers when designing new roundabouts in Abu Dhabi or other cities with similar characteristics. This research study also provides a methodological framework for other researchers when conducting similar speed studies for roundabouts in other cities or metropolitan areas around the world.

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Section: Speed Prediction Modelssupporting

confidence: 78%

Predicting Operating Speeds at Urban Multilane Roundabouts in Abu Dhabi, United Arab Emirates

Almoarawi

Dabbour

2018

Journal of Advanced Transportation

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“…As for the contributing factors in 60% of the total crashes, the geometric design of the entrance was identified as problematic in more than one-third of road users-drivers and in the same amount pavement condition, mostly friction, contributed to the crashes. Moreover, according to research by Chen et al [5] at some US and Italian roundabouts, it is suitable to get an approach-level data for models in which traffic safety is related to different predicted approach speeds. This approach could be an indirect way for developing roundabout safety models in which roundabout geometric elements are used to predict speed, which then can be used as a predictor of crash frequency.…”

Section: Introductionmentioning

confidence: 99%

Introduction of Autonomous Vehicles: Roundabouts Design and Safety Performance Evaluation

et al. 2018

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Driving experiences provided by the introduction of new vehicle technologies are directly impacting the criteria for road network design. New criteria should be taken into consideration by designers, researchers and car owners in order to assure traffic safety in changed conditions that will appear with, for example, introduction of Autonomous Vehicles (AVs) in everyday traffic. In this paper, roundabout safety level is analysed on the originally developed microsimulation model in circumstances where different numbers of AVs vehicles are mixed with Conventional Vehicles (CVs). Field data about speed and traffic volumes from existing roundabouts in Croatia were used for development of the model. The simulations done with the Surrogate Safety Assessment Model (SSAM) give some relevant highlights on how the introduction of AVs could change both operational and safety parameters at roundabouts. To further explore the effects on safety of roundabouts with the introduction of different shares of AVs, hypothetical safety treatments could be tested to explore whether their effects may change, leading to the estimation of a new set of Crash Modification Factors.

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“…Bassani and Sacchi (2011) have developed the following empirical model in Italy for estimating the roundabout circulating speed as a function of the internal circle diameter (diameter of inner edge of the circulatory roadway around the roundabout), circulatory roadway width (the width of the circular road around the roundabout), and roundabout entry width (the width of the road at the point where entering vehicle path crosses the external circle diameter) with R 2 adj. = 0.91 & SEE= 2.2: Chen et al (2013) have evaluated roundabout safety utilizing the average approach speed (AAS), which was defined as the average of entry, circulating (moving around the roundabout), and exiting speeds. They estimated the AAS as a function of the average roundabout diameter (average of inscribed circle and central island diameters) and average roundabout roadway width (average of entry, circulating and exit widths).…”

Section: Modeling Through Traffic Speed At Roundabouts Along Urban Anmentioning

confidence: 99%

Modeling Through Traffic Speed at Roundabouts Along Urban and Suburban Street Arterials

Al-Omari

Ghuzlan

Al-Helo³

2014

J Transp Res Forum

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A total of 30 roundabouts with different dimensions and characteristics were selected from three cities in Jordan. The collected data included the approaching road free flow speed (FFS), area type, entry width, circulating roadway width, exit width, roundabout internal and external circle diameters, circulating roadway super elevation, entry deviation angle, and drive curve. The regression analysis showed that the entry width, internal circulating diameter, entry deviation angle, approaching FFS, and drive curve were significant in determining the average and 85th percentile roundabout circulating speed. The developed model was compared with other international models developed in the United States and Italy.

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Investigation of models for relating roundabout safety to predicted speed

Cited by 46 publications

References 2 publications

Predicting Operating Speeds at Urban Multilane Roundabouts in Abu Dhabi, United Arab Emirates

Predicting Operating Speeds at Urban Multilane Roundabouts in Abu Dhabi, United Arab Emirates

Introduction of Autonomous Vehicles: Roundabouts Design and Safety Performance Evaluation

Modeling Through Traffic Speed at Roundabouts Along Urban and Suburban Street Arterials

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