Important properties of central island and median island at roundabouts
Abstract
The central island and median island are very important elements of a roundabout, which strongly influence the impact on traffic and safety of road users. The central island should be designed in such a way that it is perceived as an obstacle in the approach. At roundabouts with an outside diameter of more than 35.0 m, the central island should prevent the view from the approach road straight ahead to the opposite exit. This can be achieved with various design options such as trees in the central island. The layout of the central island should be customized to suit the particular local conditions. When designing the central island, it is important to factor in the requirements of buses, along with municipal and emergency vehicles. While aesthetics is a consideration, the geometric design of the intersection is a critical aspect in roundabout planning. If sufficient space is available after considering the turning radii of key vehicles, curbs can be used to define boundaries. Alternatively, paved island sections that allow partial or full traversal can be a viable option.
References
Hoffmann M. Part 5: Intersections and road traffic management (German). In: Straßenplanung und Umweltschutz. Forschungsbereich für Straßenwesen; 2008.
Hoffmann M. Guideline for traffic circles (German). Amt der Steiermärkischen Landesregierung Fachabteilung 18B; 2008.
FSV. Guidelines for planning, construction and maintenance of roads Road Planing - Road Junctions - Planning, Dimensioning, Designing - Intersections at Grade - Roundabouts (German). The Austrian Research Association for Roads, Railways and Transport; 2010.
Hoffmann M. Maintenance of roads - A contribution to life cycle costing and efficient maintenance strategies for state and municipal roads (German) [PhD thesis]. Dissertation an der Technischen Universität Graz; 2006.
FGSV. Guidelines for Urban Road Design (German). German Research Association for Roads and Traffic; 2006.
FGSV. Instruction sheet for the construction of traffic circles (German). German Research Association for Roads and Traffic; 2006.
Freistadt Sachsen. Supplementary information on the planning of traffic circles (German). Available online: https://www.verkehr.sachsen.de/download/verkehr/Ergaenzende_Hinweise_zu_KVP_Maerz_2016.pdf (accessed on 2 June 2024).
Dichtl A. Analysis of traffic circles and derivation of optimizations to reduce traffic accidents on the traffic circle lane (German) [PhD thesis]. Technische Hochschule Ingolstadt Fakultät Maschinenbau; 2023
UDV. Safety of surrounding cycle paths at traffic circles (German). Bundesministerium für Verkehr und digitale Infrastrukutur; 2006.
FUSS eV. (2007) Traffic circle information sheet 2006: Critical analysis of the information sheet (German). Available online: https://www.geh-recht.de/literatur-register.html?view=article&id=119:pg-merkblatt-kreisverkehre-2006-kritische-auseinandersetzung&catid=40 (accessed on 2 June 2024).
Land Brandenburg. Information on the design, construction and equipment of roundabouts on federal and state roads (German). Available online: https:// www.ls.brandenburg.de/media_fast/4055/Hinweise%20zur%20Kreisverkehren.15801601.pdf (accessed on 2 June 2024).
Slavchev P. Traffic circles and their impact on heavy traffic (German) [PhD thesis]. Diplomarbeit an der Technischen Universität Wien; 2008.
Al Hasanat HA, Juhász J. Development of Empirical Models to Predict Gap Acceptance Parameter Based on the Geometrical and Operational Parameters of Different Roundabouts. Periodica Polytechnica Civil Engineering; 2023. doi: 10.3311/ppci.20883
Haitham AH, Schuchmann G. Relationship between Critical Gap and Certain Geometrical Parameters in Roundabouts. Periodica Polytechnica Civil Engineering; 2022. doi: 10.3311/ppci.18628
Land OOE. Standards for traffic circles on Upper Austrian provincial roads (German). Amt der OÖ Landesregierung; 2007.
Hrapović K. Basics of Roundabout Construction (German). Available online: https://www.epubli.de/shop/buch/OSNOVE-IZGRADNJE-KRU%C5%BDNIH-RASKRSNICA-prva-knjiga-Kerim-Hrapovi%C4%87-9783752979404/101621 (accessed on 2 June 2024).
Hrapović K. Basics of Roundabout Construction, Book II - Projects of Roundabouts Implemented in Austria Berlin (German). Available online: https://www.epubli.de/shop/buch/OSNOVE-IZGRADNJE-KRU%C5%BDNIH-RASKRSNICA-druga-knjiga-Kerim-Hrapovi%C4%87-9783752979473/101628 (accessed on 2 June 2024).
NRW. Recommendations for the use and design of mini-roundabouts. Düsseldorf (German). Ministerium für Wirtschaft und Mittelstand, Technologie und Verkehr des Landes Nordrhein-Westfalen; 1999.
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