2 Example of intersection layout information collected on site (in this case, the Riccarton Road/Deans Ave roundabout in Christchurch)
The management of speed is considered an important safety issue at roundabouts. The approach speed and negotiating speed through roundabouts depends on the geometric design of the roundabout and sight distance. In New Zealand and in Australia, the design standards recommend long approach sight distances and provision of relatively high design speed...
SUBCOMMITTEE MEETING - SUMMARY OF FIVE KEY STUDIES Pedestrian and Bicycle Flow-only SPFs Mid-block Bicycle Safety – geometric features Bicycle Safety at Roundabouts Safety of Cycle Facilities at Traffic signals Pedestrian Safety at Traffic Signals
... It is generally accepted that the geometry of the roundabout affects the behavior of the driver and, thus, their overall performance [15,16]. Indeed, speed reduction is an advantage of a well-designed roundabout, which usually leads to homogeneous behavior . Roundabouts affect drivers' behavior forcing them to reduce speed in order to drive properly on the circulatory roadway. ...
This study investigated the nature and causes of unsafe driving behavior at roundabouts through an on-road study. Four urban double-lane roundabouts with different layouts were selected for an on-road study. Sixty-six drivers (41 males and 25 females) aged 18–65 years took part in the study. Unsafe behaviors observed during the in situ survey were divided into three different categories: entry unsafe behaviors, circulation unsafe behaviors, and exit unsafe behaviors. Three chi-square automatic interaction detection (CHAID) analyses were developed in order to analyze the influence of roundabout characteristics and maneuvers on unsafe behaviors at double-lane roundabouts. The results confirmed the awareness that double-lane roundabouts are unsafe and inadvisable. More than half of unsafe driving behaviors were found to be entry unsafe behaviors. Moreover, the entry radius was found to be the geometric variable most influencing unsafe driving behaviors.
... Turner vd.  dönel kavşak yaklaşımında meydana gelen kaza sayılarının hız limitinin artmasıyla arttığını bulmuştur. Ayrıca girişteki ve dolaşımdaki araçların hızlarındaki artışın, giren ve dolaşan araçlar arasında meydana gelen kazaları arttırdığını ifade etmiştir. ...
... Geometry considerations have also proven useful for analyzing driver behavior in roundabout situations and implications for traffic safety (Muffert et al., 2013;Wang et al., 2002). Methods for predicting traffic accidents have been described based on geometric elements (Maycock & Hall 1984), sight distance (Turner et al., 2009;Zirkel et al., 2013), as well as traffic dynamics and driver behavior when passing through the "potential conflict" zone of the intersection (Mauro & Cattani, 2004). ...
The popularity of roundabout application around the world is evident. Due to the inexperience of construction companies and the lack of proper national guidelines, distinctiveness in design is noticeable. In some intersections this led to reduction of Traffic (operational) Efficiency (TE). The purpose of this paper is to analyze: 1) the current state of roundabouts in Croatia; (2) known approaches to using geometry elements of roundabouts to predict TE; (3) overview and comparison of selected design guidelines; and (4) to present and comment the latest Croatian Roundabout Design Guidelines on State Roads 2014 and show examples of good practice. Research results will serve to disseminate the knowledge for proper application and implementation of national roundabouts in order to compare it with international design practice and standards.
... In rural areas, the speed of the vehicle is normally high, so providing safe sight distance is crucial. The sight distance of the roundabout depends on the approach speed and negotiating speed (Turner et al. 2009). One study investigated driver sight distance as an independent variable to predict passenger vehicle speed and vehicle crash rates at 26 singlelane roundabouts. ...
This research was focused on two issues related to multilane roundabouts on high-speed highways (speed limit 45 mph or greater) in rural and suburban areas. The first was the tradeoff between converting a traditional stop-controlled or signalized intersection to a multilane roundabout while the second was the safety of newly constructed high-speed multilane roundabouts in rural and suburban areas. The research team reviewed information from diverse published documents and conducted a survey of state and local transportation agencies. Crash data on multilane rural roundabouts were not available for this research. Therefore, the research team relied on crash and other data for single lane roundabouts that were constructed to replace rural two-way stop-controlled intersections in Kansas. To gain further insights into the safety of rural multilane roundabouts, the research team focused on investigating the safety of urban multilane roundabouts from published sources. Results of the survey indicated the need for proper design of roundabouts including signage and lighting and the potential for gaining benefits from public informational campaigns. Results of the Kansas data analysis of single lane roundabouts showed that overall all types of crashes were reduced after conversion of TWSC intersections to modern single lane roundabouts. Total crashes decreased by 58.13%; fatal crashes were reduced by 100% at all locations and non-fatal injury crashes were reduced with an overall reduction rate of 76.47%. Property-damage-only crashes were reduced by 35.49% as a whole, but two out of the four analyzed sites experienced increases in property-damage-only crashes after conversion to roundabouts. The annual value of the reduction in comprehensive crash costs from conversion of a two-way stop-controlled intersection on a rural, high-speed highway to a single lane modern roundabout was between $1.0 million and $1.6 million in 2014 dollars. A review of multilane roundabout conversions (mostly in urban areas) showed safety improvements compared to signalized and two-way stop-controlled intersections. Recommendations are presented in the report.
... The above shown Czech prediction models were compared with several other models which are used abroad and were retrieved from the literature [6,9,13,14,23,24]. They include some European examples (Belgium, France, Italy, Sweden, United Kingdom) as well as United States, Canada and New Zealand -see Fig. 8. ...
The paper presents methods of accident studies and introduces an analysis based on prediction models. In an example, roundabout accident prediction models are compared. To this end available Czech data sets have been used; a comparison with several models from abroad was conducted as well. In addition to methodology and example description a number of challenges are stressed, including data collection, analysis and interpretation. Various ways to overcoming these challenges are mentioned, including pros and cons of specific alternatives.
As roundabouts become increasingly popular, and as many communities promote bicycle use, the safety of roundabouts for people bicycling is of major concern. Although converting an intersection to a roundabout may reduce crashes overall, some research from northern Europe suggests that roundabouts may actually increase the frequency of bicycle crashes. We perform a systematic literature review on this topic, reviewing 49 different resources with empirical findings (most from Europe, some from Australia/New Zealand, few from the US). Many studies analyse (limited) bicycle crash data or observe driver/cyclist behaviours and interactions, while a few survey cyclists’ safety perceptions. Consistent with design guidance, bicycle safety performance is worse for higher-speed, multilane roundabouts and when on-roadway bike lanes are provided. Crash data and observations suggest that when cyclists “take the lane” and operate as vehicles – as is allowed or even recommended in some current design guidelines – this leads to conflicts and crashes between circulating cyclists and entering drivers who may have “looked but failed to see” (and thus failed to yield to) the cyclist. Providing separated cycle paths around the roundabout seems to be a lower-risk and more comfortable design solution, although care must be taken to encourage appropriate yielding at crossings. Future research should investigate more design features, socio-demographic characteristics, cyclist safety perceptions, and impacts outside of Europe. Studies should continue to explore ways to overcome limited bicycle crash and exposure data and to utilise naturalistic methods, driving simulators, and stated choice experiments.
Over the last 15 years a multitude of accident prediction models have been developed for rural and urban intersections and mid-block sections in New Zealand. Although used extensively, the majority of these models focused on a limited set of features that were of interest at the time. There is a growing need for more comprehensive models, similar to those developed internationally. These comprehensive models uniquely partition the safety impacts of a range of road variables, allowing simultaneous assessment of a range of features. Such models provide better prediction of the expected crash risk associated with new or changed facilities, facilitate the identification of situations with abnormally high crash risk, allow more robust assessment of a range of potential solutions, and guide the development of design standards and policies. However, the limited size of the New Zealand road network and the associated data holdings means it will be difficult and or expensive to develop robust models. This paper discusses the latest research being undertaken, in conjunctions with a researcher in Canada, into the transferability of models between North America/Europe and NZ. It presents a discussion on the differences between the models produced in each countryand the likely factors that produce these differences. This note also discusses methods that have been developed elsewhere to transfer models between the different jurisdictions, and shows how such methods can be applied in New Zealand.
This report contain all the SPFs/CPMs, AMFs/CMFs and some of the severity factors used in New Zealand. Many of which come from research by Shane Turner and others. The CEC is part of the NZ Economic Evaluation Manual. Mote also the High Risk Intersection Guide (HRIG) and High Risk Rural Road Guide (HRRRG) for other useful information.
The aim of this paper is to evaluate the impact of connected autonomous behavior in real vehicles on vehicle fuel consumption and emission reductions. Authors provide a preliminary theoretical summary to assess the driving conditions of autonomous vehicles in roundabout, which attempts exploring the impact of driving behavior patterns on fuel consumption and emissions, and including other key factors of autonomous vehicles to reduce fuel consumption and emissions. After summarizing, driving behavior, effective in-vehicle systems, both roundabout physical parameters and vehicle type are all play an important role in energy using. ZalaZONE’s roundabout is selected for preliminary test scenario establishment, which lays a design foundation for further in-depth testing.
The growth of users’ traffic demands requires a rational usage of optical fibers. Introducing of elasticity in the optical domain is a promising solution for design of the next generation optical networks. Although the elasticity provides a solution to adapt the capacity of lightpaths to the user demands, a more efficient use of resources could be obtained if that property is combined with grooming at the optical level. Optical traffic grooming involves setting up an optical tunnel that carries several connections in a contiguous block of spectrum without inserting guard bands in order to minimize the number of guard bands and optical transmitters. In this paper, we considered and classified a range of traffic grooming algorithms in elastic optical networks, including static and dynamic traffic scenario as well as spectrum engineering techniques such as multipath routing, modulation adaptive, fragmentation aware and survivable traffic grooming.