Design of median ends at at-grade intersection layout plans
Abstract
Median represents a portion of an urban road separating opposing directions of the traveled
way. Due to their function to provide enough space for separate traffic lane and storage of
left-turning vehicles, the medians are highly desirable on city arteries carrying two or more
lanes per travel direction. Type and dimensions of turning vehicles significantly affect the
design of a median openings and median ends. The design solution and the geometry of
median ends should be based on the composition of all left-turning movements occurring simultaneously
at at-grade intersection. After selection of design vehicles for swept path analysis
of the characteristic turning maneuvers in intersection, larger vehicles should be further
checked for their ability to turn without undue encroachment on adjacent traffic lanes. The
critical design parameter is the median width, especially at the ends of the median openings.
Dragging paths of left-turning vehicles shape the median ends geometry.... In traditional
design practice established in Europe, three-centered compound curves with radii rations R1
: R2 : R3 = 2 : 1 : 3 and R1 : R2 : R3 = 2.5 : 1 : 5.5 are used to approximate dragging pahs of turning
vehicles. In this paper, considering the median width, the deficiencies of the traditional
design approach are revealed and new findings regarding the design of the median ends at
at-grade intersections are presented.
Keywords:
At-grade intersection / layout plan / median end / three-centered compound curveSource:
2021Publisher:
- Department of Transportation, Faculty of Civil Engineering, University of Zagreb, Croatia