Roads and Bridges - Drogi i Mosty
14, 3, 2015, 193-202

Ellipse offset curves in the formation of turbo-roundabouts

Ryszard J. Grabowski Mail
Bialystok University of Technology, Faculty of Civil and Environmental Engineering
Published: 2015-10-16

Abstract

Various curves are used for shaping the geometry of roads and a curve applied the most often is the circular arc. Clothoid, spiral, ellipse, sets of curves shaped with polynomial functions and other similar curves are also worth mentioning. The road axis is usually set during practical realization of the curves in the terrain. The external edges are determined by measuring the width of the carriageway along the normal line to this axis. That is how two offset curves, which usually are of different type, are created. If the road axis is a circular arc with a radius R, then by displacing the width of the carriageway s along the radius of the circle, the circular arcs with radii R-s and R+s are also created, assuming that s is constant. While shaping turbo-roundabouts different curves are suggested, e.g. an ellipse. In case of its application, by displacing the width of the carriageway from its axis, the curves that fulfill the conditions of ellipses' equations are not created, but only the curves similar to them. The question is how large are the deviations? Are they important in practical realization? The analyses included in this article give answers to these questions.

Keywords


accuracy of delineating, ellipse, ellipse offset curve, turbo-roundabout

Full Text:

PDF PDF

References


Engelsman J.C., Uken M.: Turbo roundabouts as an alternative to two lane roundabout. Proceedings of the 26th Southern African Transport Conference SATC, Pretoria, South Africa, 2007

Fortuijn L.G.H.: Pedestrian and bicycle-friendly roundabouts. Dilemma of comfort and safety. Annual Meeting of the Institute of Transportation Engineers (ITE), Seattle, Washington, USA, 2003

Grabowski R.J.: Kształtowanie rond turbinowych za pomocą elipsy. Drogownictwo, LXIII, 10, 2008, 339-342

Grabowski R.J.: Turbo-roundabouts as an alternative to standard roundabouts with the circular centre island. Roads and Bridges - Drogi i Mosty, 11, 3, 2012, 215-231

Grabowski R.J.: Geometrical shaping of the turbo-circuits. Reports on Geodesy, 87, 2, 2009, 137-144

Mieszkowski P.: Ronda turbinowe. Drogownictwo, LXII, 4, 2007, 129-131

Żurowska J.: Projektowanie rond – doświadczenia i nowe tendencje. Zeszyty N-T Stowarzyszenia Inżynierów i Techników Komunikacji w Krakowie. Materiały konferencyjne, 151, 92, 2010


Ellipse offset curves in the formation of turbo-roundabouts

  
Grabowski, Ryszard J.. Ellipse offset curves in the formation of turbo-roundabouts. Roads and Bridges - Drogi i Mosty, [S.l.], v. 14, n. 3, p. 193-202, oct. 2015. ISSN 2449-769X. Available at: <>. Date accessed: 28 Mar. 2024. doi:http://dx.doi.org/10.7409/rabdim.015.013.