Roundabout Standard Editor: Arm Geometry: Entry

Expand Arm Geometry and click on the Entry tab.

The Design Speed is the speed at the yield line.

Entry Lanes refers to the number of designated lanes at the entry point.

The Entry Lane Width (Single) refers to the permitted lane width when there is only a single lane at entry. This is measured between the nearside and offside definition lines.

The Entry Lane Width (Multiple) refers to the permitted lane width when there is more than one lane at entry. This is measured between lane separator lines or between lane separator lines and definition lines in the case of the nearside and offside lanes.

The Entry Width (Overall) is the permitted overall entry width at entry. It is measured perpendicular to the splitter definition line at the intersection of the splitter definition line and the inscribed circle and is the distance between the splitter definition line and the nearside definition line.

The Splitter Radius is the radius of the offside definition line at the splitter.

The Nearside Radius is the radius of the nearside definition line at the splitter.

The Inter-Arm Radius is the radius between the current arm and the next arm. Note that this is used to connect the nearside definition lines of two adjacent arms if the lines do not intersect on the Inscribed Circle.

The Additional Lane Length is measured from the yield line where it intersects the splitter line.

The Taper Lane Length is the distance over which the entry road width changes as it adjusts to accommodate the additional lane. This is normally a significant positive value to avoid a severe step in the nearside definition line.

The Flare Lane Width is the permitted width of any extra lanes and determines when extra lane markings start.

In all cases the Max and Min values represent the limiting values from the adopted design standard and the Default value will be used when the roundabout is first placed. A default value MUST be provided but Max and Min may be blank if there is no limiting value.