This section will answer 2 main questions:
- What is a normal vs. a non-normal roundabout?
- When will I get a ‘turn right’ / ‘continue straight’ instruction vs. a ‘take the X exit’ instruction?
A non-normal roundabout:
- Will give you a ‘take the X exit’ (with arrows around it) instruction.
- Has 5 or more nodes (Ex. Each segment of a split road connects at its own node.)
- Has irregularly placed nodes (this will be covered in the examples.)
A normal roundabout:
- Will give you a ‘turn right', 'turn left’ or ‘continue straight’ instruction.
- Has up to 4 nodes, and a central node.
- All nodes are aligned within "normal" range of the entry point.
A roundabout can be both normal and non-normal at the same time depending on your entrance node.
Some examples will help explain:
- For the sake of simplicity, let’s look at a roundabout with three exits.
- The angle of the segment approaching the node does not matter, it can be similar to any of the segments below, or anywhere in between.
- Each time you approach a roundabout from one of the three nodes, an imaginary X-Y axis is drawn: (1) with the origin at the central node and (2) aligned to the entrance node.
- Coming from node #1, this is how we see the roundabout:
- Both exits 2 and 3 are within the normal range (90°±15° & 180°±15°).
- Both exits will get an instruction to ‘turn right’ or ‘continue straight’.
- Coming from node #3, this is how we see the roundabout:
- Both exits 1 and 2 are not within the ‘normal’ range – both will get a ‘take the X exit’.
- Note: even if one of these exits was within normal range, the roundabout itself will be ‘non-normal’ and all exits will get the ‘take the X exit’ prompt. The entire roundabout must be normal.