Traffic Roundabouts Research Articles

Influencing factors for right turn lane crash frequency based on geographically and temporally weighted regression models

Introduction: Right-turn lane (RTL) crashes are among the key contributors to intersection crashes in the US. Unfortunately, the lack of deep insights into understanding the effects of RTL geometric design factors on crash frequency impedes improving RTL safety performance. Method: Taking the crash data in ten counties in Indiana state from 2013 to 2016 as a case study, this study investigates the safety performance of RTL geometric configuration based on multi-sources. We introduce the geographically and temporally weighted negative binomial model (GTWNBR) to capture the space and time instability in crashes. Results: The results show that the impacts of RTL geometric design factors on crash frequency vary significantly among space and time. Several key insights can be obtained from the state-wide and multi-years crash analysis by associating the estimated parameters with road classes, localities, and counties. Conclusions: First, the RTL’s length, width, turning radius, and the installments of traffic roundabouts present higher spatiotemporal heterogeneity than other factors in modeling the crash frequency. Second, the effects of RTL’s geometric factors vary significantly across space and time. The presence of bicycle and pedestrian lanes is more likely to increase crashes in urban areas than in rural ones, especially at nighttime. Third, while exclusive RTLs decrease the crash frequency compared to the shared RTLs, the exclusive RTLs are more likely to increase the crashes for RTLs on the county road than on other road classes. Increasing RTL’s turning radius and decreasing RTL’s length is more likely to promote crashes for RTLs on county roads than on other road classes. Practical Applications: The insights provide vital guidance to improve the safety performance of geometric configuration for RTLs and intersections.

Distribution of the Roundabout Traffic

The first roundabouts as traffic engineering facilities were not built until the beginning of the 20th century, although there were islands in the middle of the streets and marketplaces long before that time. Even in Roman times, people admired the water fountains and statues in marketplaces. A long time ago in England there were also traffic islands as pedestrian oases and in France there were also the imposing buildings in the middle of market squares. However, it was only the "planning border" of all these objects that turned them into traffic roundabouts.

Combined Distributed Shared-Buffered and Diagonally-Linked Mesh Topology for High-Performance Interconnect.

Networks-on-Chip (NoCs) have become the de-facto on-chip interconnect for multi/manycore systems. A typical NoC router is made up of buffers used to store packets that are unable to advance to their desired destination. However, buffers consume significant power/area and are often underutilized, especially in cases of applications with non-uniform traffic patterns thus leading to performance degradation for such applications. To improve network performance, the Roundabout NoC (R-NoC) concept is considered. R-NoC is inspired by real-life multi-lane traffic roundabouts and consists of lanes that are shared by multiple input/output ports to maximize buffering resource utilization. R-NoC relies on router-internal adaptive routing that decides the lane path based on back pressure. Back pressure makes it possible to assess lane utilization and route packets accordingly. This is made possible thanks to the use of elastic buffers for control flow, a clever type of handshaking in a way similar to asynchronous circuits. Another prominent feature of R-NoC is that internal routing and arbitration are completely distributed which allows for significant freedom in deciding internal router topology and parameters. This work leverages this property and proposes novel yet unexplored configurations for which an in-depth evaluation of corresponding implementations on 45 nm CMOS technology is given. Each configuration is evaluated performance and power-wise on both synthetic and real application traffic. Several R-NoC configurations are identified and demonstrated to provide very significant performance improvements over standard mesh configurations and a typical input-buffered router, without compromising area and power consumption. Exploiting the distributed nature of R-NoC routers, a diagonally-linked configuration is then proposed which incurs moderate area overhead and features yet better performance and energy efficiency.

Imitation learning based decision-making for autonomous vehicle control at traffic roundabouts

The essential of developing an advanced driving assistance system is to learn human-like decisions to enhance driving safety. When controlling a vehicle, joining roundabouts smoothly and timely is a challenging task even for human drivers. In this paper, we propose a novel imitation learning based decision making framework to provide recommendations to join roundabouts. Our proposed approach takes observations from a monocular camera mounted on vehicle as input and use deep policy networks to provide decisions when is the best timing to enter a roundabout. The domain expert guided learning framework can not only improve the decision-making but also speed up the convergence of the deep policy networks. We evaluate the proposed framework by comparing with state-of-the-art supervised learning methods, including conventional supervised learning methods, such as SVM and kNN, and deep learning based methods. The experimental results demonstrate that the imitation learning-based decision making framework, which ourperforms supervised learning methods, can be applied in driving assistance system to facilitate better decision-making when approaching roundabouts.

The influence of link characteristics on road traffic noise mapping by using Big Data

This paper describes a new method developed within the BEEP project (Big data for Environmental and occupational EPidemiology) to estimate road traffic flows and to improve the truthfulness of noise maps for agglomerations through Big Data treatment. This new approach, based on data provided by Google API, acquires information regarding travel time to estimate traffic volumes using link delay functions. To achieve this goal, an appropriate experimental plan was designed to simultaneously collect travel times by Google Application Programming Interface (API) and traffic volumes on site. The experimental survey, carried out in the cities of Rome and Pisa, involved different types of road links with traffic lights or roundabouts and different number of lanes. The influence of link characteristics on the correlation between travel time and traffic flow was analysed. The method developed was used in a small area of the city of Rome, and noise maps derived by Big Data were compared to noise maps produced via conventional means.

Reliability Analysis of Intersection Sight Distance at Roundabouts

This paper presents a reliability-based method for the design of intersection sight distance (ISD) at traffic roundabouts using the linear and nonlinear deceleration profiles of the entry vehicles. The reliability method is based on the first-order second moment method which is simple and relatively accurate compared with advanced methods. The nonlinear deceleration profile includes a shape parameter that produces the linear profile as a special case. Deterministic and reliability-based formulas for the required ISD for an approaching vehicle are developed for the entry vehicle on the left and the vehicle on the circulating roadway. Then, the design values of the ISD legs, applicable to any type of roundabout, are presented for different probabilities of non-compliance (Pnc) and different coefficients of variations. For the special case of single-lane symmetrical roundabouts, which have a well-defined geometry, the lateral clearance needs are established. The sensitivity analysis shows that ISD is very sensitive to both the mean and variance of the critical headway. The results show that the deterministic method results in ISD values that correspond to a very small Pnc, indicating that the method is very conservative. The proposed method, which provides flexibility in selecting ISD for any given Pnc, should be of interest to highway designers and practitioners to promote roundabout safety.

FEATURES OF TRAFFIC NOISE ASSESSMENT AT ROUNDABOUTS IN IZHEVSK

The conditions of acoustic wave formation under urban development within traffic roundabouts are considered on the example of Izhevsk. The article refers to 5 single-level road interchanges, and provides the results of multiple acoustic measurements of the equivalent sound pressure level. The observations covered a different time range, typical for the daytime period. The average values vary from 66 to 68 dBA, and the maximum values range from 67 to 69 dBA. Based on the simulation results, acoustic discomfort zones were determined for each interchange. The variation was from 50 to 75 meters at averaged values of flows intensity (up to 1500 u / h) and from 60 to 110 meters at high intensity (up to 2000 u / h). The conclusion is made about the favorability of roundabouts from the position of noise comfort in comparison with traditional intersections equipped with traffic lights. The effectiveness of such measures is 2-3 dB.

Exploration of a scalable and power-efficient asynchronous Network-on-Chip with dynamic resource allocation

Networks-on-Chip (NoCs) are now being used to provide inter-core communication for manycore Systems-on-Chip (SoCs). This is because traditional on-chip interconnects do not scale with increasing number of cores. Typical NoCs dedicate a set of buffers to their input and/or output ports. This can lead to buffer under-utilization for applications with non-uniform traffic characteristics. In order to provide improved buffer utilization for performance gains and energy efficiency, we have proposed the Roundabout-NoC (R-NoC) concept. R-NoC is inspired by real-life multi-lane traffic roundabouts. It consists of lanes shared by multiple input/output ports. This allows the buffers to be exploited for performance gains by data-flows from multiple input ports. This work extends the asynchronous evaluation of the R-NoC, named R-NoC-A. The router is evaluated using 45 nm CMOS technology. The R-NoC-A router achieves a throughput of 465 Mflit/s and a network saturation throughput of 129 Gbps on a 4 × 4 mesh network. R-NoC-A results, in terms of performance, area and power consumption, are highly competitive to existing solutions (synchronous and asynchronous). It provides good topological trade-offs for significantly improving network performance without corresponding area overhead.

Effect of traffic roundabouts on accident rate and severity in Arizona

ABSTRACTAlthough roundabouts have been used at many locations around the world, the safety of roundabouts under different conditions has not been fully understood. In this study, 17 roundabouts in five cities in Arizona were evaluated, out of which 11 are single lane and six are double lane. Most of the intersections of single-lane roundabouts were controlled by two-way stop signs before roundabout conversion, whereas most of the intersections of double-lane roundabouts were controlled by traffic signals. Accident data were collected and broken down into five categories: damage without injury, minor injury, nonincapacitating injury, incapacitating injury, and fatality. Equal number of years were used before and after the roundabout conversion at each location. The average rates of accidents, damages without injury, injuries and fatalities per year and per million vehicles were evaluated. It was found that single-lane roundabouts reduced the accident rate, whereas double-lane roundabouts increased the accident rate. The results also showed that single- and double-lane roundabout conversions reduced the severity levels of accidents. Considering accident rate and severity level, warrants need to be developed for roundabout conversion and number of roundabout lanes under different traffic conditions.

CHAIN-WISE GENERALIZATION OF ROAD NETWORKS USING MODEL SELECTION

Abstract. Streets are essential entities of urban terrain and their automatized extraction from airborne sensor data is cumbersome because of a complex interplay of geometric, topological and semantic aspects. Given a binary image, representing the road class, centerlines of road segments are extracted by means of skeletonization. The focus of this paper lies in a well-reasoned representation of these segments by means of geometric primitives, such as straight line segments as well as circle and ellipse arcs. We propose the fusion of raw segments based on similarity criteria; the output of this process are the so-called chains which better match to the intuitive perception of what a street is. Further, we propose a two-step approach for chain-wise generalization. First, the chain is pre-segmented using circlePeucker and finally, model selection is used to decide whether two neighboring segments should be fused to a new geometric entity. Thereby, we consider both variance-covariance analysis of residuals and model complexity. The results on a complex data-set with many traffic roundabouts indicate the benefits of the proposed procedure.

Segurança de pedestres em rotatórias urbanas

Resumo Dentre as várias técnicas para abrandar as causas perniciosas provenientes dos cruzamentos no trânsito estão as rotatórias, dispositivos viários de melhor eficiência e menor custo, que têm como finalidade simplificar a interseção, para que o tráfego que se ali interage tenha um desenrolar seguro. Embora venha sendo muito utilizada no trânsito urbano brasileiro, as rotatórias priorizam o veículo motorizado devido à falta de infraestrutura, seja por opção ou carência de conhecimento técnico, para que principalmente o pedestre tenha igual segurança. Para aferir quais são os indicadores que levam a esta situação nos dispositivos, foram utilizados cinco rotatórias em São José do Rio Preto e cinco em São Carlos e proposto um confronto de conceitos técnicos entre especialistas, através do método AHP, literatura especializada e realidade constatada in loco, para verificar possíveis similaridades e diferenças existentes entre definições, conceitos e opções. Chegou-se à conclusão que a literatura e os especialistas no assunto defendem os pedestres como prioridade de projeto, implantação, infraestrutura e manutenção, entretanto os dispositivos não estão aptos a segurança dos mesmos.

Roundabouts in Northern New England, 1990 to 2010

Roundabouts are still emerging but are becoming more common as an intersection type in the United States. There is considerable pushback from the public, however, making it difficult to implement roundabouts in certain places. This study aims to develop a better understanding of the factors related to roundabout opposition in three states: Maine, New Hampshire, and Vermont. The rejected and built roundabout locations were examined within the context of geography; spatial, temporal, physical, and societal factors were included. Results of the binary logistic regression model suggest that business density and percentage of residents 65 years old and older have the strongest positive association with the likelihood of a technically feasible roundabout being built. The strongest negative association with roundabout implementation is exposure as measured by time elapsed since the first successful roundabout in the state. Proximity to traffic circles and roundabouts does not have as strong a relationship with roundabout implementation as hypothesized. The methods used, especially the inclusion of nonbuilt roundabout locations, are recommended for future research. The findings reinforce the unique challenges facing roundabout proposals in different regions of the United States; three small and mostly rural states are specifically addressed.

A90 Where, when and who: Geographic, temporal and demographic patterns in cyclist road traffic casualties in West Yorkshire

Abstract Background Research indicates that overall, the health benefits of a modal shift to cycling greatly outweigh the risks. However, the extent of these benefits appears to vary across different contexts, in terms of both geography and demography. Within the UK cycling for everyday trips remains low, but we have seen an increase in general across the country despite a decrease in London. It is therefore important to understand the balance between the risks and benefits of cycling for different groups to effectively direct cycling policy. Few studies have focused on the geographical factors that affect cycling risk at a local level. Our approach was to examine the “where, when and who” in cycling road traffic casualties, which is appropriate for developing policies at a local scale. Methods We analysed secondary data from the UK’s STATS19 dataset, which reports road accident data from 2005 to 2012. We developed an equation to measure the underlying level of exposure and examined the spatial, temporal and demographic distribution of cyclist casualties within West Yorkshire. This region was selected due to its historically low cycling rates yet ambitious plans for improvements to its cycling infrastructure. A target of a 300% increase in the rate of cycling by 2026 has been set by the West Yorkshire Integrated Transport Authority, following investment from the Department of Transport. Results West Yorkshire was found to be an unusually risky area for cyclists, with an estimated 53 deaths and 1372 serious injuries per billion kilometres cycled, based on census commuting statistics; this is roughly double the national average. This riskiness varies spatially and temporally, broadly aligning with previous literature. Cyclists were disproportionately at risk on high traffic roads, junctions and roundabouts. The proportion of traffic casualties involving cyclists has increased over time, in line with the national trend. An unexpected result was that cycling appears to be disproportionately risky for young people in West Yorkshire compared with young people nationally. Conclusions This case study progresses our understanding that risk is context-specific and geographically and demographically variable. We have shown that risk to cyclists varies within West Yorkshire, which is more risky than national average for cyclists. We conclude that the identification of local hazardous areas using the methods presented can help to prioritise investment, and inform transport policy.

Herbaceous Plants for Climate Adaptation and Intensely Developed Urban Sites In Northern Europe: A Case Study From the Eastern Romanian Steppe

AbstractIn the increasingly compact city, services currently provided for in parks will in future be compressed into smaller green unit-structures, often associated with paved surfaces. Left-over spaces in urban environments, such as traffic roundabouts and strips along paths, roads and other corridors, will be important in the future city in order to deliver different eco-system services, especially stormwater management. It is therefore essential to start now to develop the knowledge and experience needed to create sustainable plantings for these sites. This paper presents the findings of a field survey in eastern Romania that sought to identify potential species for urban paved plantings in the Scandinavian region (northern Europe). The research approach is rooted in the hypothesis that studies of natural vegetation systems and habitats where plants are exposed to environmental conditions similar to those in inner-city environments can: 1) identify new or non-traditional species and genotypes adapted to urban environments; and 2) supply information and knowledge about their use potential concerning growth, flowering, life form, etc. In total, 117 different herbaceous species, all of which experience water stress regimes comparable to those in urban paved sites in Scandinavia. The initial information obtained from this field survey present a base of knowledge of which species that have a future potential for use in urban environment, which is of great importance in the following work within this project instead of testing species randomly without this knowledge of the species tolerance and performance in similar habitats.

Comparison of Capacity of Intersection with Connection Lane on the Left of Running Lane and the other Types of Intersections

The paper deals with problems of capacity assessment of intersection with the connection lane on the left of running lane and intersections with traffic light and roundabouts. The paper describes capacity calculations for controlled intersections and roundabouts according to Czech standards and shows comparison of calculated capacity reserves of these types of intersections with reserves determined on intersection with the connection lane on the left of running lane on concrete example with real traffic flow volume values.

English

In this paper the presence of invasive and potentially invasive plant species in lawns of roads in Belgrade, the capital city of the Republic of Serbia was analysed. The following lawn categories were selected for the purpose of analysis: the lawns of traffic roundabouts, the lane-dividing lawns, the lawns around roads and lawns around highway. Five-year research was conducted on 32 sites in Belgrade and 183 plant species were recorded. Out of that number, 18 plant species (9.84%) were characterised as invasive and potentially invasive. The presence of considerable number of invasive species within the researched lawn categories, despite the specific ambient condition, made the grassy spaces of the roads the potential centre of wider spread on the surrounding areas. Considering the fact that on the researched surfaces, cultivating and maintaining measures are occasionally applied, the number of  invasive species was lower than that in the spaces not been maintained.   Key words: Invasive species, lawns, roads, invasion.

Circulation of Fluids in the Gastrovascular System of a Stoloniferan Octocoral

Cilia-based transport systems characterize sponges and placozoans. Cilia are employed in cnidarian gastrovascular systems as well, but typically function in concert with muscular contractions. Previous reports suggest that anthozoans may be an exception to this pattern, utilizing only cilia in their gastrovascular systems. With an inverted microscope and digital image analysis, we used stoloniferan octocoral colonies growing on microscope cover glass to quantitatively describe the movement of fluids in this system for the first time. Flow in stolons (diameter ≈300 μm) is simultaneously bidirectional, with average velocities of 100-200 μm/s in each direction. Velocities are maximal immediately adjacent to the stolon wall and decrease to a minimum in the center of the stolon. Flow velocity is unaffected by stolonal contractions, suggesting that muscular peristalsis is not a factor in propelling the flow. Stolon intersections (diameter ≈500 μm) occur below polyps and serve as traffic roundabouts with unidirectional, circular flow. Such cilia-driven transport may be the plesiomorphic state for the gastrovascular system of cnidarians.

SAFETY ANALYSIS OF TRAFFIC ROUNDABOUT: CONVENTIONAL VERSUS ALBERTA-TYPE MARKINGS

This paper analyzes safety at traffic roundabouts with a comparison between conventional lane marking and Alberta-type marking. A cell-based model is developed where the spatial and temporal dimensions are discretized into cells and time intervals. Based on the assumption of independent vehicular movements, a potential conflict is alleged to evolve when two or more vehicles are projected to collide into the same cell at the same time interval. Such potential conflict counts are subsequently used as a measure for quantitatively assessing the safety level of the roundabout. Our results show no significant difference between the safety level for conventional marking and for Alberta-type marking. However, the conflicts of Alberta-type marking tend to centralize at a few black spots.

Side Impact CrashesåFactors Affecting Incidence and Severity: Review of the Literature

Many traffic crashes are side impact collisions resulting in significant death and injury. A review was conducted of the evidence of driver, road, and vehicle characteristics affecting either the risk of occurrence or the severity of injury in such crashes for papers published from 1996 to early 2003. For drivers, evidence was found of increased crash risk or injury severity only for age and age-related medical conditions (e.g., dementia). Traffic roundabouts and other traffic control devices—stop signs, traffic lights, and so on—had mixed results; traffic controls were better than no controls, but their effectiveness varied with circumstance. Most vehicle characteristics have had little or no effect on crash occurrence. Antilock braking systems (ABS) in the striking vehicle had been anticipated to reduce the risk of crashes, but so far have demonstrated little effect. The primary emphasis in vehicle design has been on protective devices to reduce the severity of injury. Disparity in the size of the two vehicles, especially when the struck vehicle is smaller and lighter, is almost a consistent risk factor for occupant injury. The occupants of light trucks, however, when struck by passengers cars on the opposite side, were at higher risk of injury. Wearing seat belts had a consistently protective effect; airbags did not, but there were few studies, and no field studies, of lateral airbags found. Of all the characteristics examined, vehicle design, including occupant restraints, is the most easily modified in the short term, although road design, traffic control, and the monitoring of older drivers may also prove effective in reducing side impact crashes in the longer term.

Missed Opportunity: Use of Driver License Manuals to Educate Drivers About Roundabouts in Small- and Medium-Sized Communities

Modern roundabouts have become increasingly popular in small and medium cities in the United States because of their success in reducing speeds and collisions. According to many traffic engineers, modern roundabouts are an attractive and cost-effective speed-control device for intersections. They have been constructed in small and medium communities in California, Colorado, Florida, Indiana, Kansas, Maryland, Oregon, Utah, Washington, and Wisconsin. Geometric designs and right-of-way rules at roundabouts and traffic circles are distinct, and student drivers must be educated and informed of the correct way to use them. State driver manuals could be used to ensure fast dissemination of information to residents in small and medium communities. Review of the manuals of 32 states and the District of Columbia in 1998 and 2002 indicated that very little information is provided and by very few states. Between 1998 and 2002, only three states of those studied updated the information on roundabouts and traffic circles in the driver manuals. The manual of the state of Oregon is best for both traffic circles and roundabouts. The information in most of the manuals is covered in one sentence, and some states have used the term “traffic circle” to mean both circle and roundabout. It is imperative that the manuals be revised with adequate information on the correct way to use roundabouts so that the drivers in small and medium communities are better informed and less resistant to these devices.