Search results for "Roundabout"
showing 10 items of 70 documents
Capacity-based calculation of passenger car equivalents using traffic simulation at double-lane roundabouts
2018
Abstract Calculation of passenger car equivalents for heavy vehicles represents the starting point for the operational analysis of road facilities and other traffic management applications. This paper introduces a criterion to find the passenger car equivalents that reflect traffic conditions at double-lane roundabouts, where the capacity is typically estimated for each entry lane. Based on the equivalence defined by the proportion of capacity used by vehicles of different classes, the criterion implies a comparison between the capacity that would occur with a traffic demand of passenger cars only and the capacity reached beginning from a demand with a certain percentage of heavy vehicles. …
Understanding Safety-Related Issues for Pedestrians at Modern Roundabouts
2012
This paper examines the safety-related issues for pedestrians at modern roundabouts. For this purpose findings of research studies documented in the scientific literature and best practices have been examined trying to focus on roundabout installations by a pedestrians safety perspective. Whereas one of the main reasons for which roundabouts are built is related to safety benefits, roundabout design features and implications in road casualties have been commented first to evaluate the influence of roundabouts on pedestrian safety and then to identify design elements that have such a high potential for traffic safety. At last, measures and treatments that can be taken in the roundabouts desi…
Improving performance of roundabout intersections by optimizing traffic-flow speed
2017
Streamlining of urban traffic influence nowadays almost everything about our modern life. The main effect, which we all feel as the daily traffic participants, either as pedestrians or vehicles drivrers, is travel time to work and back. Roundabouts intersections have a number of advantages over intersections with traffic lights, they reduce the severity of accidents, traffic speeds to provide an “calmer” road environment. So, operating performance of roundabouts are complicated, influenced by the confluence operations. The paper aims at analyzing the current situation of traffic in two crowded roundabouts in Sibiu, comparing the results with the original data and proposing solutions to impr…
Calculation of turbo- roundabouts with slip lanes
2013
A turbo roundabout is a particular type of roundabout where all lanes are bounded by traffic signs and by non-mountable curbs installed at entering and circulating lanes. Turbo roundabouts also have a very particular shape to accomplish the splitting of traffic streams and to prevent cars weaving through. These aspects make turbo-roundabouts more appropriate than roundabouts when a higher level of safety has to be guaranteed, particularly in presence of relevant pedestrian and two-wheels traffic volumes. Only in some traffic conditions, turbo roundabouts can offer higher capacities than conventional double-lanes roundabouts, so if more capacity must be guarantee a bypass lane can be added t…
Turbo-Roundabouts: a Model to Evaluate Capacity, Delays, Queues and Level of Service
2012
A turbo roundabout is a particular type of roundabout where entering and circulating lanes are bounded by traffic signs and by non-mountable curbs. The physical separation between lanes, both at entries and on the ring, helps to prevent side collisions crossing the roundabout. The main advantages of turbo roundabouts are: i) reduction in the number of potential conflict points; ii) lower speed of vehicles passing through the intersection; iii) safety conditions at the intersection due to lower risk of side-by-side accidents. These aspects make turbo-roundabouts more appropriate than roundabouts when a higher level of safety has to be guaranteed, particularly in presence of relevant pedestri…
EVALUATING CAPACITY AND EFFICIENCY OF TURBO-ROUNDABOUTS.
2009
Recent evolution of roundabout design has been directed towards the so-called turbo-roundabout, with the aim of ensuring better safety conditions than those afforded by traditional schemes. The few turbo-roundabout installations so far implemented have not allowed sufficient research in order to analyze operational conditions and capacity models validated by field observations. In any case the theoretical approach to the functional study of turbo-roundabouts undoubtedly involves more complex aspects compared to typical roundabouts because of the paths of entering streams (constrained to get onto physically separated lanes), the “turbine” configuration of the circulatory carriageway, as well…
Passenger Car Equivalent for Heavy Vehicles Crossing Turbo-roundabouts
2016
Abstract Turbo-roundabouts represent an innovative scheme of modern roundabouts which provides a spiraling traffic flow and requires drivers to choose their direction before entering the intersection, since raised lane separators mark the lanes on the ring. The configuration of the turbo-roundabout makes that patterns of conflict at entries with one and two conflicting traffic streams can coexist. This paper presents research efforts aimed at measuring quantitatively the effect of heavy vehicles on operational conditions of a turbo-roundabout. The study starts from the initial belief that the greatest constraints to the vehicular trajectories imposed by the turbo-roundabout necessarily impl…
Turbo-Roundabout: Case Study of Driver Behavior and Kinematic Parameters of Light and Heavy Vehicles
2019
AbstractThis research compared kinematic and behavior parameters of light and heavy vehicles at turbo-roundabouts. This is of interest because heavy vehicles can influence turbo-roundabout function...
Application of a genetic algorithm in calibration of traffic microsimulation models
2017
This chapter describes the genetic algorithm-based calibration procedure for a microscopic traffic simulation model focusing on freeways and modern roundabouts. For both case studies, the genetic algorithm tool in MATLAB® was applied in order to reach the convergence between the outputs from Aimsun microscopic simulator and the observed data. The automatic interaction with Aimsun software was implemented through an original external Python script. Results showed that the genetic algorithm-based calibration procedure gave a better match to the observed data than simple manual calibration and the efficiency of the calibration efforts resulted significantly improved. At last, the calbrated mod…
Flower roundabouts: estimation of capacity and level of service
2012
The research work on road junction geometry, carried out in European research centres, has recently allowed to design new road intersection types which are of undoubted interest, especially in terms of traffic functionality and safety. Among the most interesting solutions there are such schemes as spiral, turbo and flower roundabouts, which are similar to traditional roundabouts. Although these solutions provide a traffic travels counterclockwise around a central island and in which entering traffic must yield to circulating traffic, the newly designed schemes generally offer modes of traffic flow regulations which highly differ from those used in conventional roundabouts. Of considerable i…