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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 ==
When representing junctions (a.k.a. , intersections, interchanges, cross roads, corners, etc.) between roads, we sometimes have the Waze map does not need to blur perfectly match the lines between the physical and logical worldsroad layouts it represents. The primary goal should be is to represent things the real world as simply as possible in the maps and only introduce complexity in the maps to deal with an issueaddress complex issues.
== The Basics &larr; START HERE basics ==This guide requires a complete understanding of editing the maps with [[Waze Map Editor]] (WME).
Lets start with === Map editing 101 ===Although it is highly recommended to read the very basic case of one road branching off from another. Most of [[editing manual]] before touching the time they will probably meet at close to a 90 degree angle. This map, it is the simplest situation to deal required that you do not continue with since this guide until you have read the physical following:* [[Map Editing Quick-start Guide|Map Editing Quick-start Guide]]* [[Creating and editing road segments#Junctions|Moving and logical views of the roads match up very well.removing junctions]]
=== Junction definition ==={| class="Wikitable floatright"| [[Image:Junction_selected.png|50px|border]]| [[Image: Uneditable_junction.png|50px|border]]| [[Image:Jct_3_90junction_unsaved.png|50px|border]]|}The [[Glossary#Junction or Junction Point|Glossary on Junctions]] provides details on how junctions can appear differently in the editor depending on its state or condition.
But you will probably find roads that A junction is made up of three things:# Two or more road [[Creating and editing road segments|segments]]# One point where all the segments meet at odd angles as well(the [[junction point]] itself)# [[Map Editing Quick-start Guide#Turn restrictions . Even in urban areas with rigid grids, you will often find at least 28allowed turns.29|Turns allowed or restricted]] when traveling from one road that has existed since prior segment to the establishment of the grid which cuts another through town at strange angles. The initial urge will be to represent the that junction as it is in the physical world - two lines running into each other at some angle.point{{clear}}
== Controlling Turn Instructions =={| class="Wikitable floatright" cellpadding="5" border="1" style="text-align: [[Imagecenter; border:Jct_3_451px solid darkgray;"|-| Keep Right || Keep Left|-| Turn Right || Turn Left|-| Exit Right || Exit Left|}Turn instructions are critical for proper client navigation. They are controlled by:* The angle set between segments at junctions.* The road names.* The road types.png]]
But there are issues with this method. Depending on Review the angles, the client may give a "Keep Right" instruction to the driver when article [[Junction Style Guide/Controlling turn instructions|controlling turn instructions]] for a "Turn Right" instruction is more appropriate. In some cases, it is even possible complete understanding of the angle may be such that no instruction is given at all. Or worse yet, the routing engine may determine that it isn't possible to make a very sharp angle requirements and not suggest a turn (in the example image, headed south and then turning left to head east)issues surrounding this topic.
To eliminate ambiguity, we need to treat the junction from a logical point of view. Since we want to 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 to add some geometry nodes to make the branch road leave the main road at close to 90 degrees, then we gradually curve to match the true departure angle.== Surface Streets ==
=== Intersections ==={| class="Wikitable floatright"| [[File:Jct 3 90.png|x100px|border]]| [[File:Jct 4 90.png|x100px|border]]| [[File: Jct ramp no geo.png|x100px|border]]|-| colspan="3"|[[ImageFile:Jct_3_45_curve4waysplitsplit.png|border|center|169x169px]]|}Basic intersections involve three or four road segments meeting at a single point. Some more complex variations resemble H or # shapes.
Now we have a junction that logically works like a basic 90 degree junction but In all cases it also fits the reality of is important to configure these intersections properly. Detailed information is covered in the physical world[[Junction Style Guide/Intersections|Intersections]] article.{{clear}}
A ramp to a highway is another good example where additional geometry nodes are helpful. Especially since most ramps diverge at a very small angle from the road.
: [[Image:Jct_ramp_no_geo.png]]=== No Outlet Roads ===
The drawback Roads which only have one way in this case (which also exists for and one way out can present challenges to the side road example above!) is that it may be very hard routing server, although they seem simple to see and click on the turn restriction arrows in the editorour minds.
: [[Image:Jct_ramp_no_geo_arrow.png]]==== Dead Ends ====
But if we just add Dead Ends (a.k.a. No Exit, Closed, No Through Road, No Outlet) are road segments that simply end, with no continuation or connections at one more geometry node end. In some areas, a Dead End may be synonymous with a [[#Cul-de-sacs|Cul-de-sac]]. In the US, a "No Outlet" sign may be used to make the departure angle at the junction indicate a road which itself closer is not a dead end, but it only connects to 45 degrees.other dead end roads.It can also be used as a "friendlier" alternative to the typical Dead End sign.
: [[Image:Jct_ramp_w_geoWithin the Map Editor it is possible to represent a dead end road with multiple segments if there are private driveways or parking lot roads mapped and connected. In that case, only the very last segment is considered the dead end segment.png]]
[[File:Jct dead end.png|left|border]]Make sure that there is a junction indicator (the small blue dot, not just a geometry node) at the very end of the segment. While this one segment does not actually constitute a junction, the small blue dot is a visual indicator to the editor that the end of this segment is properly set up.This is necessary to ensure proper routing out of the segment.now See the arrows are visible Cul-de-sac section below on when and accessiblehow to fix this.
: [[ImageFile:Jct_ramp_w_geo_arrowJct dead end ex.png|right|border|200px]]This final junction indicator must be located near the end of the road, but it should be located where there is still pavement as not to negatively impact client routes. Waze only considers the road fully traversed if both ends of the segment are fully crossed. If the junction indicator at the end of the segment happens to be at the edge of the pavement (or off of the road surface if aerials are not exactly aligned), it will be very difficult for a driver to cross that junction. A good rule of thumb is to have the end of the segment the same distance from the end of the pavement as it is from each side of the road.
We can easily scale With such a placement, the above approaches driver is given a chance to a four way cross that junctionindicator for that segment. Again we can expect to mostly see angles close to 90 degreesAlso check for the proper u-turn setting as covered in the [[Map Editing Quick-start Guide#U-Turns at the end of dead-end-streets|best practices article on u-turns]].
: [[Image:Jct_4_90.png‎ ]]==== Cul-de-sacs ====
And if we have that odd street cutting across town at an odd angle, we again want to avoid the odd angle at the junction.''See also: [http://en.wikipedia.org/wiki/Cul-de-sac Cul-de-sac article on Wikipedia]''
: [[Image:Jct_4_45A Cul-de-sac (a.k.a. Court in the US) is a common treatment of a dead end street in a residential neighborhood.png]]
In almost every situation, a cul-de-sac should be treated exactly as a dead end street, with the final junction indicator in the center of the bulb of the cul-de-sac.Be sure the free end of the final road segment has small blue dot displayed at the tip (when not editing or selecting the segment)..and we want to use geometry nodes to bring If there is no blue dot, please correct it by following the actual junction to 90 degrees. steps for You can zoom in as close as you can [[Creating and add a single geometry editing road segments#Fix the end-node on each side. This will give us the proper angle but make it virtually invisible to users so it looks just like the physical worldcul-de-sacs and dead-ends|fixing dead ends]].
: [[Image:Jct_4_45_curveJct_cul-de-sac_ex.png|left|border]]The junction indicator should be located close to the middle of the bulb and NOT near the outer edges. If the end of the segment is positioned along the perimeter of the bulb, there may be difficulty in processing client routes. Waze only considers the road fully traversed if both ends of a segment are crossed. If the end of the segment happens to be on the curb (or off of the road surface if aerials are not exactly aligned), it will be very difficult for a driver to cross the end of the road segment. With the junction in the middle of the visual road, we give a driver a good chance to cross the end of the segment no matter where they drive within the bulb. The exception to this guidance is given in the next example.{{clear}}
The above image is what you would see zoomed in {| class="Wikitable floatright"| [[Image:Jct_cul-de-sac_island_ex.png|200px|border]]| [[Image:Jct_cul-de-sac_island_ex_road.png|border|200px]]|}This cul-de-sac, with a small island, should be treated as close as possiblea basic dead end with no loop. Zoomed back outThe island can be ignored, it looks just like as there is no significant routing question for the image showing driver once they get to the junction without any geometry nodescul-de-sac.
== Controlling Turn Instructions ==As for placement of the final junction indicator, here we may get better results by moving the junction out from the true center and over to the outer perimeter of the central island. The shift ensures that the driver has a good opportunity to cross the end of the segment.{{clear}} However, if the cul-de-sac has a very large bulb with a large island in the middle, it may better be treated as a [[#Loops|Loop]]. A good rule of thumb is if you were standing at the end of the cul-de-sac, can you tell that it is just a cul-de-sac? Or does it look like two different roads? If you see an island, but are not sure if it is significant, leave the Loop out. If "Missing Road" errors occur on the road, then add a Loop.
In the Basics section above, we touched on how to ensure a === Loops ===<gallery mode="packed-hover"Turn left>File:U-shaped Road.jpg|U-shaped roadFile:Jct loop bulb.png|terminal or dead-end loop</right" instruction would be given over gallery>Road segments form a loop when you can trace a path from a "Keep left/right" instructionstarting point around to the same point without retracing any portion of the traced path.
Details ==== Every loop must be made up of the mechanics behind three or more segments ====[[File:Loop_3-part_6.jpg|right|150px]]Any loop that does not follow this rule can be found on cause problems for the Waze routing server. If there is no side-street, you must [[How_Waze_determines_turn_/_keep_/_exit_maneuversMap Editing Quick-start Guide#Splitting a segment|How Waze determines turn / keep / exit maneuversinsert an extra junction node]] pagealong the loop. Many new editors will see the extra junction node(s), but here is a quick summaryassume they are not needed, and delete them. Please educate new editors.=== Geometry ===
Some ====Two-segment loops====Two-segment loops create a situation called "same endpoint drivable segments" or "same connection segments". There are two or more ways to get from one junction node to another without going through any other nodes. They can cause a problem for the Waze app regardless of the complexity direction, or other attributes of the back-end algorithms can be avoided if we try to treat junctions with segments. This is because the logical view in mind as was done in routing server gives your mobile app a list of node IDs only, but the previous examplesapp needs to tell you which segments to drive on. If all junctions you edit follow there are two ways to get from one node to the next without going through any other nodes, then the Waze app might just have to guess. It might guess a few basic forms, it will be much easier to predict detour off the behavior of an individual junctionhighway through a service road or scenic overlook. Please save Waze from this silliness. Correct two-segment loops.
* Approximately '''90''' degree departure angle = '''Turn'''===One-segment loops====* Less than '''45''' degree departure angle = '''Keep''' ({{anchor|Loop_save_errors}}[[File:Dead end loop.png|thumb|right]] One-segment or Exit self-connected loops are often found in basemap areas. It is difficult for Ramps)Waze editors to create one-segment loops. Depending on the situation, these should be converted to three-segment loops or simple dead-end roads. For more on loops on dead-end roads, please see [[Cul-de-sac#Cul-de-sacs|cul-de-sac]]. It is important to preserve house number data on these segments.===== Fixing one-segment loops=====If you try to edit a one-segment loop, but then cannot save the changes, undo your changes and then try one of the following to fix it:
This knowledge allows us *If the loop and the road leading to control how a junction behaves by modifying a single geometry node in most casesit have the '''same''' name*#Select the loop and the road. This *#Click the bridge icon that appears (one end of the loop will disconnect from the other)*#Move the now free end of the loop so it is often useful for [[At-Grade_Connectors|At-Grade Connectors]] where sometimes we prefer slightly separated*#Save*If the loop and the road leading to it have '''different''' names*#Draw a "Keep rightnew road segment that connects to the loop/left" road junction*#Give that new road the same exact name as the loop*#Select the loop and the new road segment*#Click the bridge icon that appears (one end of the loop will disconnect from the other times )*#Move the now free end of the loop so it is slightly separated*#Save*Create a "Turn right/left" would be more dead end road or a three-segment dead-end loop as appropriate.*Fix elevations.*Confirm turns.
If we keep the departure angle less than 45 degrees, we would get Here is a "Keep Right" to follow [http://www.youtube.com/watch?v=a7yAzG7HElw video on YouTube showing the curved one-way connectorsecond method].{{#widget:YouTube|id=a7yAzG7HElw}}
: [[Image:Jct_at_grade_keepJct_roundabout.png|frameless|right]]
But if we move one geometry node ===Roundabouts and traffic circles===It may be tempting to use the roundabout feature to create a 90 degree angleloop shape. Do not do this unless the loop is a roundabout or traffic circle. Roundabouts give special routing instructions, and must not be used for other purposes. To learn more, now we would receive a "Turn Right" instructionplease see the [[Roundabout]] page.
: [[Image:Jct_at_grade_turn.png]]=== At-grade connectors ===
=== Segment Naming and Type ===: [[Image:Jct_at_grade_keep.png]]
Besides the geometry With exceptions, don't set these segments as ramps! Watch out for all of the road segmentsturns you need to restrict. For a more detailed discussion, see the names and types of the segments come into playfull [[At-grade connectors]] article.
A basic rule of thumb is that if you want a turn to be announced, having a different name will improve the chances that will happen. For the At-Grade Connector example above, the connector should have a different name than the road it is leaving (See the [[At-Grade_Connectors#How_to_name_the_connector|How to name the connector]] section of the At-Grade Connectors page).== Interchanges and ramps ==
== Roundabouts An '''interchange''' is a road junction where two roads are connected by dedicated roadways, called '''ramps'''. The roads connected by an interchange do not intersect one another directly, and Traffic Circles ==if they cross, the crossing is grade-separated.
Please see the [[Roundabout]] page for a full discussion of this special type of junction.=== When to use ramps ===
== Use of the {{Ramp}} type is governed by the following rules:* [[Road types]]* [[At-Grade Connectors ==grade connectors]]
: [[Image:Jct_at_grade_keep.png]]=== Ramp and interchange style ===
Make sure you don't confuse these segments for For guidance on the proper configuration of ramps! And watch out for turns you need to restrict. For a full discussion, interchanges and wayfinders, see the [[At-Grade_Connectors|At-Grade ConnectorsJunction Style Guide/Interchange]] page.
== Limited Access Interchanges Special Cases ==When two roads meet in === Transitions ==={| class="Wikitable floatright"| [[Image:Jct_transition.png|x150px|border]]| [[Image:Jct_transition_90.png|x150px|border]]|}A transition is a limited access interchange (any situation where travel between the roads is facilitated by ramps alone), extra care must be takennon-junction depicted using a junction node.
If an exit ramp lines up with an entrance ramp, care must be taken to restrict the straight through direction to prevent "ramp-to-ramp routing" Valid examples of where the routing engine may try to take use a shortcut from the Freeway, to the exit ramp, to the entrance ramp, and back to the Freeway instead Transition node include:# Road name changes# City Limits# Road Direction changes# Part of staying on the Freeway. That motion is inefficient and may be illegal in certain jurisdictions.a [[#Loops|Loop Road]]# Speed Limit Change
'''Care must be taken Before the current house numbering system came into use, transition nodes were used to not enable all turns aid in any situation where ramps meet unless all possible flows of traffic have been considered!'''house numbering, but that is no longer required.
=== Diamond Interchange ===: [[Image:Jct_diamondThere 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]]
In the simplest formAs long as you are '''certain''' it is not a valid transition node, this can a superfluous junction node may be represented as single connections from [[Map Editing Quick-start Guide#Delete a Junction|deleted]]. Doing so will simplify the ramps map, eliminate turn restrictions to maintain, and reduce computing resource needs. Also consider removing the surface street[[Creating and editing road segments#Adjusting road geometry . Just be sure to restrict 28nodes.29|geometry node]] which will replace the straight through motion from the exit ramp onto the entrance rampjunction node you delete, if that geometry node is not needed.
: [[Image:Jct_diamond_simple_turns=== Roads to Nowhere ===In certain situations it may be necessary to add road segments that are un-drivable in order to provide accurate navigation instructions.png]]
If ==== Actual ====A valid use of this technique is at the ramps connect temporary end of a freeway. As a freeway is built, it is often opened in sections, up to the surface street at multiple points, a certain exit. If we have map this as a regular freeway segment leading to avoid a ramp-to-ramp routing as well as illegal turns which should use another ramp. First we see the turns that must segment, no announcement will be restricted made for that final exit, no matter what we name the exit ramps:ramp.
: [[Image:Jct_diamond_cplx_turns_off_LThis 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.png]] [[Image:Jct_diamond_cplx_turns_off_RImagine traveling down a freeway and seeing your next instruction is "turn left at Main St." You would probably wonder if there was a map error since you shouldn't be making a left turn off of a freeway.png]]
Then If we see what must be restricted for map even just a little of the entrance ramps:future path of the freeway, this gives the routing engine a junction which will generate an "exit" instruction at the end of the freeway, thus eliminating any confusion.
: [[Image:Jct_diamond_cplx_turns_onConversely, 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]]
== Oddities ==
=== Offset Roads ===
[[Image:Jct_4_offset.png|left|x150px|border]]Sometimes you will find two roads which cross , where one does not quite line up exactly from one side to with the 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_offsetJct_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_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}}
There are [[Image:Jct_4_offset_sep_ex.png|left|x150px|border]]Since we want to avoid very short segments of road (the GPS chips in consumer devices can be very inaccurate which may make it seem that a few things we need driver skipped right over a short segment. 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 look at shift the side roads as far apart from each other as possible with them still in this situationthe proper location (along the far curb lines for a residential street for example). This will maximize the length of the short segment between the side roads.
# Do the roads actually line up in reality? If so we need to modify the junction to be a basic 4 way junction.[[Category:Style Guide]]# 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 only done while zoomed in very close.<br/>[[ImageCategory:Jct_4_offset_align.pngTable examples]]<br/># 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. Since we want to avoid very short segments of road, it may be wise to shift the side roads as far apart from each other as possible with them still in the proper location (along the far curb lines for a residential street for example). This will maximize the length of the short segment between the side roads.