# Changes

## Junction Style Guide

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The following article contains key information on properly creating junctions and the roadways between them. Be sure to review it in its entirety before editing the map.
== Simple is better ==
=== Ramp and interchange style ===
== The Basics ==For guidance on the proper configuration of ramps, interchanges and wayfinders, see [[Junction Style Guide/Interchange]].
Lets start with the very basic case of one road branching off from another== Special Cases ===== Transitions ==={| class="Wikitable floatright"| [[Image:Jct_transition. Most of the time they will probably meet at close to a 90 degree anglepng|x150px|border]]| [[Image:Jct_transition_90. This png|x150px|border]]|}A transition is the simplest situation to deal with since the physical and logical versions of the roads match up very wella non-junction depicted using a junction node.
Valid examples of where to use a Transition node include:# Road name changes# City Limits# Road Direction changes# Part of a [[Image:Jct_3_90.png#Loops|Loop Road]]# Speed Limit Change
But you will probably find roads that meet at odd angles as well. Even Before the current house numbering system came into use, transition nodes were used to aid in urban areas with rigid gridshouse numbering, you will often find at least one road but that has existed since prior to the establishment of the grid which cuts through town at strange angles. The initial urge will be to represent the junction as it is in the physical world - two lines running into each other at some angleno longer required.
[[Image:Jct_3_45There may be existing transition nodes on the map for other reasons like remaining after a connecting road is deleted, inherited from the original base map import when rivers and streams created junctions, etc.png]]
But there As long as you are issues with this method'''certain''' it is not a valid transition node, a superfluous junction node may be [[Map Editing Quick-start Guide#Delete a Junction|deleted]]. Depending on Doing so will simplify the anglesmap, the client may give a "Keep Right" instruction eliminate turn restrictions to maintain, and reduce computing resource needs. Also consider removing the driver when a "Turn Right" instruction is more appropriate[[Creating and editing road segments#Adjusting road geometry .28nodes. In some cases29|geometry node]] which will replace the junction node you delete, it is even possible the angle may be such if that no instruction geometry node is given at all. Or worse yet, the routing engine may determine that it isn't possible to make a very sharp angle and not suggest a turn (in the example image, headed south and then turning left to head east)needed.
To eliminate ambiguity, we need to treat the junction from a logical point of view. Since we want === Roads to Nowhere ===In certain situations it may be given basic "Turn Left" and "Turn Right" instructions, we have to treat it like it was a basic 90 degree intersection. But how do we do that when the roads don't actually diverge at 90 degrees? What we need to do is necessary to add some geometry nodes to make the branch road leave the main road at close segments that are un-drivable in order to 90 degrees, then we gradually curve to match the true departure angleprovide accurate navigation instructions.
[[Image:Jct_3_45_curve==== Actual ====A valid use of this technique is at the temporary end of a freeway. As a freeway is built, it is often opened in sections, up to a certain exit. If we map this as a regular freeway segment leading to a ramp segment, no announcement will be made for that final exit, no matter what we name the exit ramp.png]]
Now we have This can be confusing if the ramp is set up as a properly signed and numbered exit, especially if a driver is traveling a long distance on this freeway. Imagine traveling down a freeway and seeing your next instruction is "turn left at Main St." You would probably wonder if there was a junction that logically works like map error since you shouldn't be making a basic 90 degree junction but it also fits the reality left turn off of the physical worlda freeway.
We can easily scale If we map even just a little of the future path of the above approaches to freeway, this gives the routing engine a four way junction. Again we can expect to mostly see angles close to 90 degreeswhich will generate an "exit" instruction at the end of the freeway, thus eliminating any confusion.
[[Image:Jct_4_90Conversely, if we do NOT want an exit instruction at the end of a freeway, ensure there are no road segments extending past the final exit, to ensure the final exit is the only path out of the final freeway segment.png‎ ]]
And if we have that odd street cutting across town at an odd angle=== Offset Roads ===[[Image:Jct_4_offset.png|left|x150px|border]]Sometimes you will find two roads which cross, we again want to avoid the odd angle at where one does not quite line up with the junction..other.
There are a few things we need to look at in this situation.{{clear}}:* Do the roads actually line up in reality? If so we need to modify the junction to be a basic 4-way junction.{| class="Wikitable floatright"|[[Image:Jct_4_offset_align.png|x150px|border]]|[[Image:Jct_4_offset_align_ex.png|x150px|border]]|}:* Do the roads ALMOST line up in reality? If you were giving instructions to a person and would tell them to go straight with no mention of any slight turn or jog, then we want to make it into a 4-way junction. You may need to "split the difference" and not follow the centerline of either road to achieve this. The angles are exaggerated in this next example to show how the junction is forced to be close to 90 degrees, then we taper to the true centerlines of the roads. In practice this can be much more gradual and/or done while zoomed in very close.[[Image:Jct_4_45Jct_4_offset_ex.png|right|x150px|border]]:* Finally, is there a true separation between the roads? Would you need to say for example "turn left then make an immediate right"? If so then we will want to leave the junction such that the two sides do not align.{{clear}}
[[Image:Jct_4_offset_sep_ex...and png|left|x150px|border]]Since we want to use geometry nodes to bring avoid very short segments of road (the actual junction to 90 degreesGPS chips in consumer devices can be very inaccurate which may make it seem that a driver skipped right over a short segment. You can zoom This will result in [[Map Problems in Waze Map Editor|automated map errors]] and possible route recalculations in the client,) it may be wise to shift the side roads as close far apart from each other as you can and add possible with them still in the proper location (along the far curb lines for a single geometry node on each sideresidential street for example). This will give us maximize the proper angle but make it virtually invisible to users so it looks just like length of the short segment between the physical worldside roads.
[[ImageCategory:Jct_4_45_curve.pngStyle Guide]][[Category:Table examples]]