In some cases, moving a grip or changing a value in the Roundabout Properties dialog may cause a warning triangle to be displayed. These occur when a value goes outside the limits recommended by the adopted standard. Alongside the warning triangle, a short description of the problem is displayed. The visibility and format of this short warning is controlled by the Warning Symbol style. If there is a symbol within the triangle, it provides additional information. For example, in our example, ‘< -3.04’ means that the inscribed circle diameter is 3.04m less than the minimum recommended in the standard. These values update dynamically so you should be able to grip edit your roundabout quite precisely without resorting to the roundabout properties.
In addition, if you move the cursor over the center of the triangle, a longer, more detailed warning text is displayed, e.g. ‘The current value for Inscribed Circle Diameter (24.9604) is less than the minimum value specified in the standard (28.0000)’. The visibility and format of these longer messages is controlled by the Warning Symbol Floating Text style.
Even though US standards require checks of only R1 to R3 on through paths, only R4 on left turns and only R5 on right turns, internally AutoCAD Civil 3D 2017 calculates the entry, circulating and exit radii of all paths through the roundabout.
We show the fastest path from each leg based upon the R1 to R5 values and display the relevant R1 to R5 values in the HUD. However, having identified the fastest route, we then check the entry and exit radius of the right and left turns against the limiting values for R1 and R3 respectively.
You may therefore see warnings for radii and/or speeds that do not equate to one of the values in the HUD.