Hi
I am a designer in NSW, Australia. I am currently trying to develop a civil cell for a median island at a signalised intersection, but I am encountering some trouble getting a single radius median nose to work as I intend it due to greyed out snaps during the design process. According to the RMS Traffic Signal Design Guide, the nose of the island has to be offset 0.3m from the crossing line, as can be seen below:
To achieve this, I am trying to draw a radius that is tangential to 3 separate lines - the two outer edges of the median and a line dictating the 0.3m offset from the crossing line. The radius of the nose would be dependent on the width of the median. The scenario can be seen below (The arc below was created using Microstation arc tools, not ORD Geometry):
The problem I encounter is that using ORD Geometry, it seems impossible to achieve the scenario described. I have been currently using the Arc Between Points (Start / End / Pass-through) to try and snap tangentially to the 3 lines, and while it works for the start and end snaps, but when it comes to selecting the "Pass-through" point it will not let me snap to the third line as the tangential snap greys out and becomes unusable. I had also tried using Arc Between Elements, but that has no option of selecting a third point.
My question is:
1. Is the scenario I am describing possible with ORD Geometry tools?
2. If not, then why are some crucial snaps removed from use when using certain ORD Geometry Tools?
Thanks
Jake