New Type of Roundabout: Dual One-Lane Roundabouts on Two Levels with Right-Hand Turning Bypasses – ’’Target Roundabout’’

Abstract

The problems of low level traffic safety on multi-lane roundabouts have been resolved in various ways in different countries, usually by using alternative types of roundabouts that reduce the number of conflict points. Alternative types of roundabouts typically differ from "normal" or "standard" roundabouts in one or more design elements, as their implementation purposes could also be specific. Today, several different types of roundabouts are already in use ("mini", "double mini", "dumb-bell", those "with joint splitter islands" ("dog-bone"), those "with a spiralling circular carriageway" ("turbo"), those "with depressed lanes for right-hand turners" ("flower") etc.). This paper introduces a new type of roundabout, dual one-lane roundabouts on two levels with right-hand turning bypasses, namely the "target roundabout". This paper describes and analyses their design, traffic safety, and capacity characteristics, compared with the standard two-lane roundabouts. Problem nizke ravni prometne varnosti v obstojeÄih veÄpasovnih kroÅ¾nih kriÅ¾iÅ¡Äih se v razliÄnih drÅ¾avah reÅ¡uje na razliÄne naÄine, obiÄajno z uvedbo alternativnih tipov kroÅ¾nih kriÅ¾iÅ¡Ä, v katerih je Å¡tevilo konfliktnih toÄk praviloma manjÅ¡e. Za alternativne tipe kroÅ¾nih kriÅ¾iÅ¡Ä je tipiÄno, da se od ânormalnihâ oz. âstandardnihâ kroÅ¾nih kriÅ¾iÅ¡Ä razlikujejo v enem ali veÄ projektnoâtehniÄnih elementov, specifiÄni pa so lahko tudi pogoji njihove izvedbe. Danes je Å¾e znanih veliko razliÄnih tipov kroÅ¾nih kriÅ¾iÅ¡Ä (âminiâ, âdvojni miniâ, âdumbâbellâ, âs povezanima loÄilnima otokomaâ (âdog-boneâ), âs spiralnim potekom kroÅ¾nega voziÅ¡Äaâ (âturboâ), âs pritisnjenimi pasovi za desne zavijalceâ (âflowerâ), â¦) in njihov razvoj bo zagotovo potekal tudi v prihodnosti. Prispevek prikazuje novi tip kroÅ¾nega kriÅ¾iÅ¡Äa, dvonivojski enopasovni kroÅ¾ni kriÅ¾iÅ¡Äi s pasovi za desne zavijalce, krajÅ¡e âtarget roundaboutâ. V prispevku so predstavljene njegove projektnoâtehniÄne, prometnoâvarnostne in kapacitetne lastnosti, primerjaje z obiÄajnim dvopasovnim kroÅ¾nim kriÅ¾iÅ¡Äem.