Junction Style Guide: Difference between revisions Discussion View history

Latest revision as of 21:54, 29 August 2022

Images are going to be added to clarify these instructions.

This revision of the page is currently undergoing modifications. The information and guidance is currently considered accurate enough to be followed now. Content is being prepared by one or more users. Do not make any changes before you post a message in this forum. Please use the talk page for thoughts and ideas on setting up this content.

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, intersections, interchanges, cross roads, corners, etc., the Waze map does not need to perfectly match the road layouts it represents. The primary goal is to represent the real world as simply as possible in the maps and only introduce complexity in the maps to address complex issues.

The basics

This guide requires a complete understanding of editing the maps with Waze Map Editor (WME).

Map editing 101

Although it is highly recommended to read the editing manual before touching the map, it is required that you do not continue with this guide until you have read the following:

Junction definition

The Glossary on Junctions provides details on how junctions can appear differently in the editor depending on its state or condition.

A junction is made up of three things:

Two or more road segments
One point where all the segments meet (the junction point itself)
Turns allowed or restricted when traveling from one segment to another through that junction point

Controlling Turn Instructions

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.

Review the article controlling turn instructions for a complete understanding of the requirements and issues surrounding this topic.

Surface Streets

Intersections

Basic intersections involve three or four road segments meeting at a single point. Some more complex variations resemble H or # shapes.

In all cases it is important to configure these intersections properly. Detailed information is covered in the Intersections article.

No Outlet Roads

Roads which only have one way in and one way out can present challenges to the routing server, although they seem simple to our minds.

Dead Ends

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 end. In some areas, a Dead End may be synonymous with a Cul-de-sac. In the US, a "No Outlet" sign may be used to indicate a road which itself is not a dead end, but it only connects to other dead end roads. It can also be used as a "friendlier" alternative to the typical Dead End sign.

Within 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.

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. See the Cul-de-sac section below on when and how to fix this.

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.

With such a placement, the driver is given a chance to cross that junction indicator for that segment. Also check for the proper u-turn setting as covered in the best practices article on u-turns.

Cul-de-sacs

A Cul-de-sac (a.k.a. Court in the US) is a common treatment of a dead end street in a residential neighborhood.

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). If there is no blue dot, please correct it by following the steps for fixing dead ends.

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.

This cul-de-sac, with a small island, should be treated as a basic dead end with no loop. The island can be ignored, as there is no significant routing question for the driver once they get to the cul-de-sac.

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.

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 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.

Loops

U-shaped road
terminal or dead-end loop

Road segments form a loop when you can trace a path from a starting point around to the same point without retracing any portion of the traced path.

Every loop must be made up of three or more segments

Any loop that does not follow this rule can cause problems for the Waze routing server. If there is no side-street, you must insert an extra junction node along the loop. Many new editors will see the extra junction node(s), assume they are not needed, and delete them. Please educate new editors.

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 direction, or other attributes of the segments. This is because the routing server gives your mobile app a list of node IDs only, but the app needs to tell you which segments to drive on. If 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 detour off the highway through a service road or scenic overlook. Please save Waze from this silliness. Correct two-segment loops.

One-segment loops

One-segment or self-connected loops are often found in basemap areas. It is difficult for 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. 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:

If the loop and the road leading to it have the same name
1. Select the loop and the road.
2. Click the bridge icon that appears (one end of the loop will disconnect from the other)
3. Move the now free end of the loop so it is slightly separated
4. Save
If the loop and the road leading to it have different names
1. Draw a new road segment that connects to the loop/road junction
2. Give that new road the same exact name as the loop
3. Select the loop and the new road segment
4. Click the bridge icon that appears (one end of the loop will disconnect from the other)
5. Move the now free end of the loop so it is slightly separated
6. Save
Create a dead end road or a three-segment dead-end loop as appropriate.
Fix elevations.
Confirm turns.

Here is a video on YouTube showing the second method.

Roundabouts and traffic circles

It may be tempting to use the roundabout feature to create a loop 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, please see the Roundabout page.

At-grade connectors

With exceptions, don't set these segments as ramps! Watch out for all of the turns you need to restrict. For a more detailed discussion, see the full At-grade connectors article.

Interchanges and ramps

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 if they cross, the crossing is grade-separated.

When to use ramps

Use of the Ramp type is governed by the following rules:

Ramp and interchange style

For guidance on the proper configuration of ramps, interchanges and wayfinders, see Junction Style Guide/Interchange.

Special Cases

Transitions

A transition is a 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 Loop Road
Speed Limit Change

Before the current house numbering system came into use, transition nodes were used to aid in house numbering, but that is no longer required.

There 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.

As long as you are certain it is not a valid transition node, a superfluous junction node may be deleted. Doing so will simplify the map, eliminate turn restrictions to maintain, and reduce computing resource needs. Also consider removing the geometry node which will replace the junction node you delete, if that geometry node is not needed.

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.

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.

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 map error since you shouldn't be making a left turn off of a freeway.

If we map even just a little of the 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.

Conversely, 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.

Offset Roads

Sometimes you will find two roads which cross, where one does not quite line up with the other.

There are a few things we need to look at in this situation.

Do the roads actually line up in reality? If so we need to modify the junction to be a basic 4-way junction.

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.

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.

We want to avoid very short segments of road because some GPS chips in consumer devices can be very inaccurate which may make it seem that a driver skipped right over a short segment. This will result in automated map errors and possible route recalculations in the client. Therefore, 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.

@@ Line 1: / Line 1: @@
-== Simple is better ==
+{{NeedImage}}
+<!--Editorial Reminders--><!--To Do - U-Turn Solutions for "Road not connected" error -->
+{{construction
+| contact     = https://www.waze.com/forum/viewtopic.php?f=1636&t=283510
+| contacttype = forum
+| draft       = no
+| open        = no
+| revision    = yes
+| talk        = yes
+}}
-When representing junctions (a.k.a. intersections, cross roads, corners, etc.) between roads, we sometimes have to blur the lines between the physical and logical worlds.  The primary goal should be to represent things as simply as possible and only introduce complexity to deal with an issue.
+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.
-== The Basics &larr; START HERE ==
+== Simple is better ==
-Lets start with the very basic case of one road branching off from another.  Most of the time they will probably meet at close to a 90 degree angle.  This is the simplest situation to deal with since the physical and logical views of the roads match up very well.
+When representing junctions, intersections, interchanges, cross roads, corners, etc., the Waze map does not need to perfectly match the road layouts it represents. The primary goal is to represent the real world as simply as possible in the maps and only introduce complexity in the maps to address complex issues.
-: [[Image:Jct_3_90.png]]
+== The basics ==
+This guide requires a complete understanding of editing the maps with [[Waze Map Editor]] (WME).
-But you will probably find roads that meet at odd angles as well.  Even in urban areas with rigid grids, you will often find at least one road 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 angle.
+=== Map editing 101 ===
+Although it is highly recommended to read the [[editing manual]] before touching the map, it is required that you do not continue with this guide until you have read the following:
+* [[Map Editing Quick-start Guide|Map Editing Quick-start Guide]]
+* [[Creating and editing road segments#Junctions|Moving and removing junctions]]
-: [[Image:Jct_3_45.png]]
+=== Junction definition ===
+{| class="Wikitable floatright"
+| [[Image:Junction_selected.png|50px|border]]
+| [[Image:Uneditable_junction.png|50px|border]]
+| [[Image:junction_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 there are issues with this method.  Depending on the angles, the client may give a "Keep Right" instruction to the driver when a "Turn Right" instruction is more appropriate.  In some cases, it is even possible 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 and not suggest a turn (in the example image, headed south and then turning left to head east).
+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 (the [[junction point]] itself)
+# [[Map Editing Quick-start Guide#Turn restrictions .28allowed turns.29|Turns allowed or restricted]] when traveling from one segment to another through that junction point
+{{clear}}
-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.
+== Controlling Turn Instructions ==
+{| class="Wikitable floatright" cellpadding="5" border="1" style="text-align:center; border: 1px solid darkgray;"
-: [[Image:Jct_3_45_curve.png]]
+|-
+| Keep Right || Keep Left
-Now we have a junction that logically works like a basic 90 degree junction but it also fits the reality of the physical world.
+|-
+| Turn Right || Turn Left
-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.
+|-
+| 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.
-: [[Image:Jct_ramp_no_geo.png]]
+Review the article [[Junction Style Guide/Controlling turn instructions|controlling turn instructions]] for a complete understanding of the requirements and issues surrounding this topic.
-The drawback in this case (which also exists for the side road example above!) is that it may be very hard to see and click on the turn restriction arrows in the editor.
+== Surface Streets ==
-: [[Image:Jct_ramp_no_geo_arrow.png]]
+=== 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"|[[File:4waysplitsplit.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.
-But if we just add one more geometry node to make the departure angle at the junction itself closer to 45 degrees...
+In all cases it is important to configure these intersections properly. Detailed information is covered in the [[Junction Style Guide/Intersections|Intersections]] article.
+{{clear}}
-: [[Image:Jct_ramp_w_geo.png]]
-...now the arrows are visible and accessible.  Note that you can also press 's' in the editor to '''s'''pread or '''s'''eparate the arrows at a junction if you still have difficulty clicking on an arrow.  (see [[Keyboard_shortcut|Editor Keyboard Shortcuts]] for more tips.)
+=== No Outlet Roads ===
-: [[Image:Jct_ramp_w_geo_arrow.png]]
+Roads which only have one way in and one way out can present challenges to the routing server, although they seem simple to our minds.
-We can easily scale the above approaches to a four-way junction.  Again we can expect to mostly see angles close to 90 degrees.
+==== Dead Ends ====
-: [[Image:Jct_4_90.png‎ ]]
+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 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 indicate a road which itself is not a dead end, but it only connects to other dead end roads. It can also be used as a "friendlier" alternative to the typical Dead End sign.
-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...
+Within 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.
-: [[Image:Jct_4_45.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. See the Cul-de-sac section below on when and how to fix this.
-...and we want to use geometry nodes to bring the actual junction to 90 degrees.  You can zoom in as close as you can and add a single geometry 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 world.
+[[File:Jct 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.
-: [[Image:Jct_4_45_curve.png]]
+With such a placement, the driver is given a chance to cross that junction indicator for that segment. Also 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]].
-The above image is what you would see zoomed in as close as possible.  Zoomed back out, it looks just like the image showing the junction without any geometry nodes.
+==== Cul-de-sacs ====
-== Controlling Turn Instructions ==
+''See also: [http://en.wikipedia.org/wiki/Cul-de-sac Cul-de-sac article on Wikipedia]''
-In the Basics section above, we touched on how to ensure a "Turn left/right" instruction would be given over a "Keep left/right" instruction.
+A Cul-de-sac (a.k.a. Court in the US) is a common treatment of a dead end street in a residential neighborhood.
-Details of the mechanics behind this can be found on the [[How_Waze_determines_turn_/_keep_/_exit_maneuvers|How Waze determines turn / keep / exit maneuvers]] page, but here is a quick summary.
+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). If there is no blue dot, please correct it by following the steps for  [[Creating and editing road segments#Fix the end-node on cul-de-sacs and dead-ends|fixing dead ends]].
-=== Geometry ===
-Some of the complexity of the back-end algorithms can be avoided if we try to treat junctions with the logical view in mind as was done in the previous examples.  If all junctions you edit follow just a few basic forms, it will be much easier to predict the behavior of an individual junction.
+[[Image:Jct_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}}
-* Approximately '''90''' degree departure angle = '''Turn'''
+{| class="Wikitable floatright"
-* Less than '''45''' degree departure angle = '''Keep''' (or Exit for Ramps)
+| [[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 a basic dead end with no loop. The island can be ignored, as there is no significant routing question for the driver once they get to the cul-de-sac.
-This knowledge allows us to control how a junction behaves by modifying a single geometry node in most cases.  This is often useful for [[At-Grade_Connectors|At-Grade Connectors]] where sometimes we prefer a "Keep right/left" and other times a "Turn right/left" would be more appropriate.
+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}}
-If we keep the departure angle less than 45 degrees, we would get a "Keep Right" to follow the curved one-way connector:
+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.
-: [[Image:Jct_at_grade_keep.png]]
+=== Loops ===
+<gallery mode="packed-hover">
+File:U-shaped Road.jpg|U-shaped road
+File:Jct loop bulb.png|terminal or dead-end loop
+</gallery>
+Road segments form a loop when you can trace a path from a starting point around to the same point without retracing any portion of the traced path.
-But if we move one geometry node to create a 90 degree angle, now we would receive a "Turn Right" instruction.
+==== Every loop must be made up of three or more segments ====
+[[File:Loop_3-part_6.jpg|right|150px]]Any loop that does not follow this rule can cause problems for the Waze routing server. If there is no side-street, you must [[Map Editing Quick-start Guide#Splitting a segment|insert an extra junction node]] along the loop. Many new editors will see the extra junction node(s), assume they are not needed, and delete them. Please educate new editors.
-: [[Image:Jct_at_grade_turn.png]]
+====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 direction, or other attributes of the segments. This is because the routing server gives your mobile app a list of node IDs only, but the app needs to tell you which segments to drive on. If 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 detour off the highway through a service road or scenic overlook. Please save Waze from this silliness. Correct two-segment loops.
-=== Segment Naming and Type ===
+====One-segment loops====
+{{anchor|Loop_save_errors}}
+[[File:Dead end loop.png|thumb|right]] One-segment or self-connected loops are often found in basemap areas. It is difficult for 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:
-Besides the geometry of the road segments, the names and types of the segments come into play.
+*If the loop and the road leading to it have the '''same''' name
+*#Select the loop and the road.
+*#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 slightly separated
+*#Save
+*If the loop and the road leading to it have '''different''' names
+*#Draw a new road segment that connects to the loop/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)
+*#Move the now free end of the loop so it is slightly separated
+*#Save
+*Create a dead end road or a three-segment dead-end loop as appropriate.
+*Fix elevations.
+*Confirm turns.
-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).
+Here is a [http://www.youtube.com/watch?v=a7yAzG7HElw video on YouTube showing the second method].
+{{#widget:YouTube|id=a7yAzG7HElw}}
-== Roundabouts and Traffic Circles ==
-: [[Image:Jct_roundabout.png]]
+===Roundabouts and traffic circles===
+[[Image:Jct_roundabout.png|frameless|right]]
+It may be tempting to use the roundabout feature to create a loop 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, please see the [[Roundabout]] page.
+{{Clear}}
-Please see the [[Roundabout]] page for a full discussion of this special type of junction.
+=== At-grade connectors ===
-== At-Grade Connectors ==
+[[Image:Jct_at_grade_keep.png|left|300px]]With exceptions, don't set these segments as ramps! Watch out for all of the turns you need to restrict. For a more detailed discussion, see the full [[At-grade connectors]] article.
-: [[Image:Jct_at_grade_keep.png]]
+== Interchanges and ramps ==
-Make sure you don't confuse these segments for ramps!  And watch out for turns you need to restrict.  For a full discussion, see the [[At-Grade_Connectors|At-Grade Connectors]] page.
+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 if they cross, the crossing is grade-separated.
-== Limited Access Interchanges ==
+=== When to use ramps ===
-See also: [http://en.wikipedia.org/wiki/Interchange_(road) Wikipedia article on Road Interchanges]
-When two roads meet in a limited access interchange (any situation where travel between grade separated roads is facilitated by ramps alone), extra care must be taken.
+Use of the {{Ramp}} type is governed by the following rules:
+* [[Road types]]
+* [[At-grade connectors]]
-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" where the routing engine may try to take a shortcut from the Freeway, to the exit ramp, to the entrance ramp, and back to the Freeway instead of staying on the Freeway. That motion is inefficient and may be illegal in certain jurisdictions.
+=== Ramp and interchange style ===
-'''Care must be taken to not enable all turns in any situation where ramps meet unless all possible flows of traffic have been considered!'''
+For guidance on the proper configuration of ramps, interchanges and wayfinders, see [[Junction Style Guide/Interchange]].
-We also have to pay attention to the '''Level''' of the road segments since there will typically be many bridges and overpasses for any limited access interchange.  If two roads cross without connecting, their levels must be different.
+== Special Cases ==
+=== Transitions ===
+{| class="Wikitable floatright"
+| [[Image:Jct_transition.png|x150px|border]]
+| [[Image:Jct_transition_90.png|x150px|border]]
+|}
+A transition is a non-junction depicted using a junction node.
-=== Diamond Interchange ===
+Valid examples of where to use a Transition node include:
-: [[Image:Jct_diamond.png]]
+# Road name changes
-See also: [http://en.wikipedia.org/wiki/Diamond_interchange Diamond Interchange article on Wikipedia]
+# City Limits
+# Road Direction changes
+# Part of a [[#Loops|Loop Road]]
+# Speed Limit Change
-In the simplest form, this can be represented as single connections from the ramps to the surface street.  Just be sure to restrict the straight through motion from the exit ramp onto the entrance ramp.
+Before the current house numbering system came into use, transition nodes were used to aid in house numbering, but that is no longer required.
-: [[Image:Jct_diamond_simple_turns.png]]
+There 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.
-If the ramps connect to the surface street at multiple points, we have to avoid ramp-to-ramp routing as well as illegal turns which should use another ramp.  First we see the turns that must be restricted for the exit ramps:
+As long as you are '''certain''' it is not a valid transition node, a superfluous junction node may be [[Map Editing Quick-start Guide#Delete a Junction|deleted]]. Doing so will simplify the map, eliminate turn restrictions to maintain, and reduce computing resource needs. Also consider removing the [[Creating and editing road segments#Adjusting road geometry .28nodes.29|geometry node]] which will replace the junction node you delete, if that geometry node is not needed.
-: [[Image:Jct_diamond_cplx_turns_off_L.png]]  [[Image:Jct_diamond_cplx_turns_off_R.png]]
+=== 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.
-Then we see what must be restricted for the entrance ramps:
+==== 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.
-: [[Image:Jct_diamond_cplx_turns_on.png]]
+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 map error since you shouldn't be making a left turn off of a freeway.
-'''Note on Levels:'''
+If we map even just a little of the 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.
-The single surface street segment between the inner most ramps should be either raised or lowered in relation to the freeway segments depending on the actual geography at the interchange.
-=== Single Point Urban Interchange (SPUI) ===
+Conversely, 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.
-: [[Image:Jct_SPUI.png]]
-See also: [http://en.wikipedia.org/wiki/Single-point_urban_interchange Single Point Urban Interchange article on Wikipedia]
-A SPUI is a very space and flow efficient design, but it takes extra attention to ensure the turns are correct.  And as the name indicates, ideally there should be a single junction in the center.  You may need to tweak the geometry of segments a bit off of alignment from the real physical world, but it should be minor if the interchange is a true SPUI.
-The outer branches of the exit ramps are very much like in the case of a diamond interchange:
-: [[Image:Jct_SPUI_off_outer_turn.png]]
-Where things get complicated is the inner branches leading to the Single Point.  You need to avoid ramp to ramp in two directions and a reverse flow turn.
-: [[Image:Jct_SPUI_off_inner_turn.png]]
-Luckily the entrance ramp restrictions are similar to the diamond interchange:
-: [[Image:Jct_SPUI_on_turn.png]]
-If you were to look at all the restricted turns at once, you may get the false impression that something is very wrong.  But as you now know, a SPUI has almost as many restricted turns as allowed ones.
-: [[Image:Jct_SPUI_all_turns.png]]
-'''Note on Levels:'''
-The two surface street segments (between the outer ramps and connected to the Single Point) and the 4 ramp segments connected to the single point should all be the same level, either one higher or one lower than the level of the freeway segments above/below the single point.
-== Oddities ==
 === Offset Roads ===
-Sometimes you will find two roads which cross where one does not quite line up exactly from one side to the other.
+[[Image:Jct_4_offset.png|left|x150px|border]]
+Sometimes you will find two roads which cross, where one does not quite line up with the other.
-: [[Image:Jct_4_offset.png]]
+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_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 a few things we need to look at in this situation.
+[[Image:Jct_4_offset_sep_ex.png|left|x150px|border]]
+We want to avoid very short segments of road because some GPS chips in consumer devices can be very inaccurate which may make it seem that a 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. Therefore, 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.
-# 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 guides]][[Category:Table examples]]
-# 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/>[[Image:Jct_4_offset_align.png]]<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.

Search