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Junction Style Guide

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When representing The following article contains key information on properly creating junctions (a.k.a. intersections, cross roads, corners, etc.) between roads, we sometimes have to blur and the lines roadways between the physical and logical worldsthem. The primary goal should be Be sure to represent things as simply as possible and only introduce complexity to deal with an issuereview it in its entirety before editing the map.
== The Basics &larr; START HERE Simple is better == A junction is made up of three things:# At least two roads# One or more places these roads meet (a junction node)# Turns allowed or restricted at those junction nodes If you do not know how to create and modify roads, junctions, or turns, please read [[Map_Editing_Quick-start_Guide|the Map Editing Quick-start Guide]]. 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. : [[Image:Jct_3_90.png]] 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. : [[Image:Jct_3_45.png]] 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). 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. : [[Image:Jct_3_45_curve.png]] Now we have a junction that logically works like a basic 90 degree junction but it also fits the reality of the physical world. Here is a completed real world example: : [[Image:Jct_3_45_ex.png]] 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]] 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. : [[Image:Jct_ramp_no_geo_arrow.png]] But if we just add one more geometry node to make the departure angle at the junction itself closer to 20 or 30 degrees... : [[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.) : [[Image:Jct_ramp_w_geo_arrow.png]] We can easily scale the above approaches to a four-way junction. Again we can expect to mostly see angles close to 90 degrees. : [[Image:Jct_4_90.png‎ ]] 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... : [[Image:Jct_4_45.png]]
When representing junctions, intersections, interchanges, cross roads, corners, etc., the Waze map does not need to perfectly match the road layouts it represents..and we want The primary goal is to use geometry nodes to bring represent the actual junction to 90 degrees. You can zoom in real world as close simply as you can possible in the maps and add a single geometry node on each side. This will give us only introduce complexity in the proper angle but make it virtually invisible maps to users so it looks just like the physical worldaddress complex issues.
: == The basics ==This guide requires a complete understanding of editing the maps with [[Image:Jct_4_45_curve.pngWaze Map Editor]](WME).
The above image === Map editing 101 ===Although it is what you would see zoomed in as close as possible. Zoomed back outhighly recommended to read the [[editing manual]] before touching the map, it looks just like the image showing is required that you do not continue with this guide until you have read the junction without any geometry nodes.following:* [[Map Editing Quick-start Guide|Map Editing Quick-start Guide]]* [[Creating and editing road segments#Junctions|Moving and removing junctions]]
And here is a real world example at a zoom level where you === 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 still see appear differently in the geometry adjustment we added:editor depending on its state or condition.
A junction is made up of three things: # Two or more road [[Image:Jct_4_45_exCreating 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.png29|Turns allowed or restricted]]when traveling from one segment to another through that junction point{{clear}}
== Controlling Turn Instructions ==
{| class="Wikitable floatright" cellpadding="5" border="1" style="text-align:center; border: 1px 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.
Before going further, make sure you understand Review the mechanics of article [[Map_Editing_Quick-start_Guide#Turn_restrictions_.28allowed_turns.29Junction Style Guide/Controlling turn instructions|controlling turn restrictionsinstructions]] in for a complete understanding of the Map Editor. If turns are not properly enabled requirements and restricted, you will never get the instructions you desireissues surrounding this topic.
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.== Surface Streets ==
Details of the mechanics behind this can be found on the === Intersections ==={| class="Wikitable floatright"| [[How_Waze_determines_turn_/_keep_/_exit_maneuversFile:Jct 3 90.png|How Waze determines turn / keep / exit maneuversx100px|border]] page, but here is a quick summary| [[File:Jct 4 90.png|x100px|border]]| [[File:Jct ramp no geo.png|x100px|border]]|-| colspan=== Geometry ==="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.
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 In all junctions you edit follow just a few basic forms, cases it will be much easier is important to predict configure these intersections properly. Detailed information is covered in the behavior of an individual junction[[Junction Style Guide/Intersections|Intersections]] article.{{clear}}
* Approximately '''90''' degree departure angle = '''Turn'''
* Between '''20 and 30''' degree departure angle = '''Keep''' (or Exit for Ramps)
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.=== No Outlet Roads ===
If we keep the departure angle Roads which only have one way in and one way out can present challenges to the 20 to 30 degree rangerouting server, we would get a "Keep Right" although they seem simple to follow the curved one-way connector:our minds.
: [[Image:Jct_at_grade_keep.png]]==== Dead Ends ====
But if we move 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 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 create indicate a road which itself is not a 90 degree angledead end, now we would receive but it only connects to other dead end roads. It can also be used as a "Turn Rightfriendlier" instructionalternative to the typical Dead End sign.
: [[Image:Jct_at_grade_turnWithin 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]]
Similar rules apply for [[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 that the segment as well. If we have While this one segment does not actually constitute a junction, the small blue dot is a 20 visual indicator to 30 degree angle as pictured above, there will be no turn instruction as traffic just smoothly slides into the cross street. But if we make editor that the end of this segment is properly set up. This is necessary to ensure proper routing out of the segment close . See the Cul-de-sac section below on when and how to a 90 degree angle, then there would be a turn right instruction for the driverfix this.
=== Segment Naming and Type ===[[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.
Besides With such a placement, the geometry of 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 road segments, [[Map Editing Quick-start Guide#U-Turns at the names and types end of the segments come into playdead-end-streets|best practices article on u-turns]].
A basic rule of thumb is that if you want a turn to be announced, having a different name will improve the chances (but not guarantee!!!) that it 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). === Highway/Freeway Junctions ===These are junctions involving the three Highway/Freeway road types - Minor Highway, Major Highway, and Freeway -- as well as their Ramps.==== Highway/Freeway Exits ====It is considered to be a basic Exit situation when a "straight" direction is obvious to a driver and navigation instructions are only needed for the non-straight direction (the exit). If navigation instructions are required for both directions, see the [[#Highway/Freeway_Splits|Highway/Freeway Splits]] section below. To be treated as a basic Exit, the following must be true:# The entering segment and one exiting segment must be one of the three Highway/Freeway types# The Highway/Freeway exiting segment must have close to a zero degree departure angle from the entering segment# The second exiting segment must be of type Ramp# The Ramp exiting segment must had a departure angle of between 20 and 30 degrees from the entering segment With those conditions met, the junction will present an "Exit Right/Left" navigation instruction when the ramp is used and will remain silent with no navigation instructions at all when using the Highway/Freeway exiting segment. ==== Highway/Freeway Splits ====We will consider it to be a Highway/Freeway Split when we have a Highway/Freeway segment meeting at a junction with two other Highway/Freeway segments where there is no obvious straight through direction to a driver. To receive a navigation instruction for '''both''' branches of a split, the following must be true:# All segments must be one of the 3 Highway/Freeway Types# All segments must have names which are different from each other# The two exiting segments must have departure angles of 20 to 30 degrees from the entering segment# The segment can be short, but it should be large enough that it is not hard to find in the editor ''(too subjective, we probably need a minimum length guideline)'' With those conditions met, the junction will present "Keep Left" and "Keep Right" navigation instructions using the name of the appropriate exiting segment.==== Ramp to Ramp Splits ====A ramp may itself split and branch into two directions. If this is the case, "Exit Right" and "Exit Left" will be announced using the name of the appropriate exiting segment in all cases. === Surface Street Junctions ======= Y Intersections ==== == 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 the human mind. === Dead Ends === Dead Ends (a.k.a. No Exit, Close, 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. 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 node (not just a geometry node) at the very end of the segment. This is necessary to ensure proper routing out of the segment. : [[Image:Jct_dead_end.png]] === Cul-de-sacs ===
''See also: [http://en.wikipedia.org/wiki/Cul-de-sac Cul-de-sac article on Wikipedia]''
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 node 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]].
: [[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}}
If the {| 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 has , with a very large bulb with an small island in the middle, it may better should be treated as a [[#Loops|Loop]] if the size truly significant. A simple basic dead end should with no loop. The island can be our initial design thoughignored, and a Loop only used if problems with "Missing Road" errors occuras there is no significant routing question for the driver once they get to the cul-de-sac.
=== Loops ===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 are |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 that ? If you can enter and without turing aroundsee an island, but are not sure if it is significant, end up at leave the Loop out. If "Missing Road" errors occur on the same place you startedroad, then add a Loop.
The important Map Editor rule we must follow is=== Loops ===<gallery mode="packed-hover">File: '''a U-shaped Road.jpg|U-shaped road segment must ''not'' start and File:Jct loop bulb.png|terminal or dead-end on loop</gallery>Road segments form a loop when you can trace a path from a starting point around to the same junction node'''point without retracing any portion of the traced path.
If ==== 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 not followedno side-street, you must [[Map Editing Quick-start Guide#Splitting a segment|insert an extra junction node]] along the routing server loop. Many new editors will have difficulty in providing routes into see the extra junction node(s), assume they are not needed, and out of the loopdelete them. Please educate new editors.
Hopefully there will be ====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 roadway along without going through any other nodes. They can cause a problem for the loop road which you can mapWaze app regardless of the direction, which will break or other attributes of the segments. This is because the loop into two pieces and avoid routing server gives your mobile app a list of node IDs only, but the problemapp needs to tell you which segments to drive on. But if If there are no interruptions two ways to get from one node to the next without going through any other nodes, then the loop and Waze app might just have to guess. It might guess a detour off the entire loop is represented by one highway through a service road or scenic overlook. Please save Waze from this silliness. Correct two-segment that doubles back on itself, we have a problemloops.
To properly handle this ====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, we must insert a superfluous junction node along the loop these should be converted to three-segmentloops or simple dead-end roads. For more on loops on dead-end roads, please see [[Cul-de-sac#Cul-de-sacs|cul-de-sac]]. The specific location does not matterIt is important to preserve house number data on these segments.===== Fixing one-segment loops=====If you try to edit a one-segment loop, but most people put it near then cannot save the half-way point of the segment changes, undo your changes and/or opposite then try one of the true junction node.following to fix it:
: [[Image:Jct_loop_bulb*If the loop and the road leading to it have the '''same''' name*#Select the loop and the road.png]] [[Image:Jct_loop_square*#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.png]]
'''NOTE:''' It Here is very easy for you or another editor to find the superfluous junction node, assume it is truly superfluous, and delete it! This problem is magnified if the loop road is large or shaped in a way where it is not obvious that it is a loop[http://www.youtube. So if you can identify a road to map along com/watch?v=a7yAzG7HElw video on YouTube showing the loop, even if it is a parking lot, that would provide a more "permanent" treatment of the loop since the superfluous junction node now serves an obvious purposesecond method].{{#widget:YouTube|id=a7yAzG7HElw}}
== Roundabouts and Traffic Circles ==[[Image:Jct_roundabout.png|frameless|right]]
: ===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 [[Image:Jct_roundabout.pngRoundabout]]page.
Please see the [[Roundabout]] page for a full discussion of this special type of junction. === At-Grade Connectors grade connectors ===
: [[Image:Jct_at_grade_keep.png]]
Make sure you With exceptions, don't confuse set these segments for as ramps! And watch Watch out for all of the turns you need to restrict. For a full more detailed discussion, see the full [[At-Grade_Connectors|At-Grade Connectorsgrade connectors]] pagearticle.
== Ramps Interchanges and ramps ==
Ramps have An '''interchange''' is a very specific purpose in Waze. They road junction where two roads are intended to connect segments of Minor Highwaysconnected by dedicated roadways, Major Highwayscalled '''ramps'''. The roads connected by an interchange do not intersect one another directly, and Freeways to roads where there are no atif they cross, the crossing is grade-grade crossingsseparated.
=== When to use ramps ===
The Use of the {{Ramp}} type is governed by the following conditions must be met for the use of ramps to be appropriaterules:# Two roads cross over/under each other with no at-grade junction# At least one of the roads are of these * [[Road types]]## Minor Highway## Major Highway## Freeway## Ramp If the above requirements are not satisfied, you may be dealing with an * [[#At-Grade_Connectors|At-Grade Connectorgrade connectors]]. === How complex should ramps be? === Rule #1 is still simpler is better. So unless there is a large deviation of distance between paths at the end of a ramp (either into or out of the ramp as appropriate), a single segment connecting to a single junction node is all that is needed. The simple existence of a painted, concrete, or grass island is '''NOT''' enough of a reason to split a ramp into multiple ramps.
: [[Image:Jct_ramp_no_split.png]]=== Ramp and interchange style ===
Once paths at For guidance on the end proper configuration of the ramp deviate significantly in distanceramps, regardless of the existence of any type of islandinterchanges and wayfinders, then it is time to consider multiple rampssee [[Junction Style Guide/Interchange]].
== Special Cases ===== Transitions ==={| class="Wikitable floatright"| [[Image: Jct_transition.png|x150px|border]]| [[Image:Jct_ramp_splitJct_transition_90.png|x150px|border]]|}A transition is a non-junction depicted using a junction node.
== Limited Access Interchanges ==Valid examples of where to use a Transition node include:# Road name changes# City Limits''See also: # Road Direction changes# Part of a [[http://en.wikipedia.org/wiki/Interchange_(road) Wikipedia article on #Loops|Loop Road Interchanges]'']# Speed Limit Change
When two roads meet Before the current house numbering system came into use, transition nodes were used to aid in a limited access interchange (any situation where travel between grade separated roads house numbering, but that is facilitated by ramps or slip roads alone), extra care must be takenno longer required.
If an exit ramp lines up with an entrance ramp, care must There may be taken to restrict existing transition nodes on the straight through direction to prevent "ramp-to-ramp routing" where the routing engine may try to take map for other reasons like remaining after a shortcut connecting road is deleted, inherited from the Freeway, to the exit ramp, to the entrance ramporiginal base map import when rivers and streams created junctions, and back to the Freeway instead of staying on the Freeway. That motion is inefficient and may be illegal in certain jurisdictionsetc.
As long as you are '''Care must certain''' it is not a valid transition node, a superfluous junction node may be taken [[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 enable all turns in any situation where ramps meet unless all possible flows of traffic have been considered!'''needed.
We also have === Roads to pay attention Nowhere ===In certain situations it may be necessary to the '''Level''' of the add 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 differentthat are un-drivable in order to provide accurate navigation instructions.
The following sections discuss some ==== Actual ====A valid use of this technique is at the common Interchange designstemporary end of a freeway. As a freeway is built, it is often opened in sections, up to a certain exit. Note If we map this as a regular freeway segment leading to a ramp segment, no announcement will be made for that some Interchanges may be a hybrid of these basic designs where one side or quadrant of the interchange may differ from final exit, no matter what we name the othersexit ramp.
=== Diamond Interchange ===: [[Image:Jct_diamondThis 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.png]]'" You would probably wonder if there was a map error since you shouldn'See also: [http://ent be making a left turn off of a freeway.wikipedia.org/wiki/Diamond_interchange Diamond Interchange article on Wikipedia]''
Common in wide open spaces where land acquisition and geography are not concernsIf we map even just a little of the future path of the freeway, this Interchange design has ramps equally distributed across all 4 quadrantsgives the routing engine a junction which will generate an "exit" instruction at the end of the freeway, thus eliminating any confusion.
In Conversely, if we do NOT want an exit instruction at the simplest formend of a freeway, this can be represented as single connections from ensure there are no road segments extending past the ramps final exit, to ensure the surface street. Just be sure to restrict the straight through motion from final exit is the exit ramp onto only path out of the entrance rampfinal freeway segment.
: [[Image:Jct_diamond_simple_turns.png]]
 
If the ramps connect to the surface street at multiple points (be sure to read [[#How_complex_should_ramps_be?|How complex should ramps be?]], 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:
 
: [[Image:Jct_diamond_cplx_turns_off_L.png]] [[Image:Jct_diamond_cplx_turns_off_R.png]]
 
Then we see what must be restricted for the entrance ramps:
 
: [[Image:Jct_diamond_cplx_turns_on.png]]
 
'''Note on Levels:'''
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.
 
=== Cloverleaf Interchange ===
: [[Image:Jct_cloverleaf.png]]
 
''See also: [http://en.wikipedia.org/wiki/Cloverleaf_interchange Cloverleaf Interchange article on Wikipedia]''
 
In a Cloverleaf Interchange, left turns are eliminated from all movements between the Freeway and the surface street. First check the exit ramps.
 
: [[Image:Jct_cloverleaf_off_outer_turns.png]] [[Image:Jct_cloverleaf_off_inner_turns.png]]
 
Then check the entrance ramps for illegal turns.
 
: [[Image:Jct_cloverleaf_on_turns.png]]
 
The connections to the Freeway segments may be treated in two ways:
 
:[[Image:Jct_cloverleaf_options.png]]
 
# (top) we can have the inner entrance and exit ramps have their own junction nodes with the Freeway.
# (bottom) we can have the entrance and exit ramps share a single junction node with the Freeway. This allows us to eliminate the very short Freeway segment that may exist between the inner entrance and exit ramps.<br />It is best to offset this shared junction onto the Entrance ramp side of the surface street. This prevents the junction from accidentally being connected to the surface street or looking like it does. We favor the Entrance ramp side, because this would result in a slightly earlier exit instruction which is of course preferred over a late exit instruction.
 
The determining factor of which design to use will partly depend on the actual size and scale of the specific interchange.
 
'''Note on Levels:'''
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.
 
=== Folded Diamond ===
: [[Image:Jct_folded_diamond.png]]
''See also: Discussion of Folded Diamonds and A2/B2 Partial Cloverleafs on the [http://en.wikipedia.org/wiki/Partial_cloverleaf_interchange Partial Cloverleaf Interchange article on Wikipedia]''
 
Geography or property ownership may prevent the ability for an interchange to be constructed with all ramps evenly distributed across the 4 quadrants of the interchange. When only two quadrants are used, it is typically called a Folded Diamond (basically a sub-type of a Partial Cloverleaf Interchange). The ramps may be all on one side (as in the examples in this section) or they may be located in diagonally opposed quadrants.
 
The unique situation presented by the Folded Diamond arrangement is having both Entrance and Exit ramps terminating on the same side of the surface street. Ideally both ramps should terminate on the same junction node to permit us to easily restrict the illegal and usually impossible ramp-to-ramp movement.
 
: [[Image:Jct_folded_diamond_u-turn.png]]'
 
Like with a basic Diamond Interchange, often it will be necessary to represent the ramps making multiple connections to the surface street (Be sure to read [[#How_complex_should_ramps_be?|How complex should ramps be?]]. Restrict all non-permitted turns.
 
: [[Image:Jct_folded_diamond_off_turns_L.png]] [[Image:Jct_folded_diamond_off_turns_R.png]] [[Image:Jct_folded_diamond_on_turns.png]]
 
'''Note on Levels:''' Similar to a basic Diamond interchange, in most cases only the segment of the surface street that crosses the Freeway segments will need to be adjusted up or down.
 
=== Single Point Urban Interchange (SPUI) ===
: [[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. '''Note:''' The ramp-to-ramp motion to facilitate a U-Turn (the top left arrow in the image below) may or may not be allowed depending on the specific interchange. Please validate this 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 ===
[[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.# 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]] [[ImageCategory:Jct_4_offset_align_ex.pngStyle Guide]]<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.<br />[[Image:Jct_4_offset_ex.png]]<br />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.<br /> [[ImageCategory:Jct_4_offset_sep_ex.pngTable examples]]