Junction boxes (JBs) are used to improve ETA calculations and routing through complicated intersections, and interchanges. Junction boxes are displayed as multiple segments with multiple inputs and outputs. They are basically a hint editors can give the Waze routing services that “although these few segments are cut in a few places, they generally should be treated as a single point which connects traffic from several sources”.
Considering a complex intersection as a single point has several beneficial properties:
- Traffic speed data for each path through the junction box can be collected separately.
- Turn restrictions can also be separately controlled for each path through the junction box.
- Voice prompts can be separately controlled for each path through the junction box.
- Turn instructions can be separately controlled for each path through the junction box.
- The shape of a junction box cannot be changed afterwards
- You cannot create new junction nodes in a junction box
- You cannot move a junction node out of the junction box
- If you're going to draw a junction box, make sure you can see all the segments you want in it, otherwise you'll end up with strange, incomplete paths.
For ETA purposes, the routing server does not consider segments wholly within the junction box, but rather treats the junction box as if all the segments which enter or exit the the junction box are connected to at a single junction node.
Junction boxes are considered only by the routing server. Junction boxes have no effect on navigational prompts. Junction boxes have no visibility in the client or on the live map. Junction boxes do not effect the search engine; the origin or destination of route may be contained in a junction box.
For editing a junction box L4 is needed. The segment with the highest lock within a JB determines the auto lock level of the JB.
- A junction box cannot exceed 0.01° latitude and 0.01° longitude: around 1 x 1 KM.
- A junction box must include at least two junction nodes which must be connected by a segment.
- A junction node cannot be included in multiple junction boxes.
- No more than 16 controllable entry/exit paths can pass through a single-junction node within a junction box.
- Adjacent connections not displayed in the routing box list are also counted.
- Having u-turns enabled on a two-way segment increases the number of paths.
- The page on Junction Boxes over Roundabouts
For an extensive explanation of the Junction Box see: