Unnecessary junctions: Difference between revisions Discussion View history

Latest revision as of 06:25, 14 August 2022

Ideally, a roadway should be continuous with junctions only appearing when other roads or ramps intersect. Unfortunately, when the original Tiger maps were loaded, junctions were placed at every location where two roads appeared to cross. Since an overpass may 'appear' to intersect with a freeway from a two dimensional view a lot of unneeded junctions were added to the map. Generally unnecessary junctions are not harmful, but they are better to be removed if truly unnecessary.

Are any two-segment junctions ever necessary?

Sometimes there are reasons for junctions with only two segments. These include:

Loop roads. A single segment cannot loop back upon itself, so a junction is required to create two separate segments. It does not matter where the junction is located, so long as each segment meets the minimum segment length. Some roads have two separate segments that share the same start and end junctions creating two alternate paths between them. These configurations cause routing problems and require one of the two segments to have a 2-segment junction. More details are covered in Junction Style Guide on Loops.

Ramp or freeway splits. There are cases where a freeway may split into two separate freeways. In order to provide navigation to drivers, it may be necessary to create short segments on the freeway to show the two different road names at the split. Under certain situations it may be best to make the segments as short as possible, so long as each segment meets the minimum segment length. This is covered in detail in the Junction Style Guide.

Long segments. Segments are best kept under a certain distance. See the article segment length for more information.

Segment Property Change. When a segment property changes between intersections, a two-segment junction may be required:

Road, city, or state name change. When the road, city, or state name changes between intersections, add a junction so the segments on either side may have a different name.

Elevation Change. When elevation changes at complex interchanges, a junction can be added to introduce an elevation change.

Speed Limit Change. When the speed limit changes between intersections, add a junction so the segments on either side may have a different speed limit.

Removal justification

If any of the above criteria are present, do not remove the junction. Otherwise, the two-segment junction is unnecessary and can be removed.

Identification on the map

The two ends of a segment are highlighted when it is selected in WME. If each end of that segment does not have at least two other segments connecting to the end, it may be an unnecessary junction. Be sure to review the criteria above before removing it.

Removal best practices

After reviewing the criteria above to be sure the junction is not necessary, when you select the junction in question, if you see the trash can icon in the upper right corner then you can click the trash can to remove the junction. Two other less advisable methods are bridging the segments and dragging them together.

If the trash can icon does not appear, it means the junction separates two segments that are not identical. Possibly the road, city, or state name is different. It also may indicate one of the connected segments are locked above your editing rank. Last, the segments may have different routing directions, so check them to be sure they are set correctly.

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-Ideally, a freeway or highway should be a continuous roadway, with junctions only appearing when ramps enter and exit the roadway.  Unfortunately, when the Tiger maps were loaded, the Waze 'admin' user placed junctions at EVERY place where 2 roads appeared to cross.  Since an overpass may 'appear' to intersect with a freeway, at least to a computer program, waze put a lot of junctions on the map.  I've seen junctions with crossing bike paths, rivers, walking paths, etc.  But, to have a junctioning map for automobile navigation, we need to remove unnecessary junctions.
+Ideally, a roadway should be continuous with junctions only appearing when other roads or ramps intersect. Unfortunately, when the original Tiger maps were loaded, junctions were placed at every location where two roads appeared to cross. Since an overpass may 'appear' to intersect with a freeway from a two dimensional view a lot of unneeded junctions were added to the map. Generally unnecessary junctions are not harmful, but they are better to be removed if truly unnecessary.
-<ol>
-<li>'''Unnecessary junctions defined'''
+==Are any two-segment junctions ever necessary?==
-Easy.  If the real road does not really join to the other road at a Waze junction, then take the junction out.  This includes junctions that are in the middle of a freeway.  In other words, a freeway segment that only connects to another freeway segment of the same freeway (with no ramp involved) has a junction that should be removed so it becomes one longer freeway segment.  Also, junctions in the middle of a field, etc are useless so take them off too
+Sometimes there are reasons for junctions with only two segments. These include:
+{{:Necessary junctions}}
-</li>
+==Removal justification==
+If any of the above criteria are present, do not remove the junction. Otherwise, the two-segment junction is unnecessary and can be removed.
-<li>'''How to find Unnecessary junctions'''
+==Identification on the map==
-If they are on top, you can easily find junctions by clicking on (highlighting) a freeway segment and then check each end of the segment, if it ends before the junction for a ramp, then it is an unneeded junction.  Sometimes the junctions are not so easy to see because they are buried under a road.  Usually, you stumble upon hidden junctions when your navigation on some route goes haywire.  You may need to pull the map apart and examine the road segment you were traveling. You also may need to temporarily move a road segment out of the way, so you can look for junctions underneath.  Then move the road back.
+The two ends of a segment are highlighted when it is selected in [[WME]]. If each end of that segment does not have at least two other segments connecting to the end, it may be an unnecessary junction. Be sure to review the criteria above before removing it.
-</li>
+==Removal best practices==
-<li>'''How best to remove a junction'''
+After reviewing the criteria above to be sure the junction is not necessary, when you select the junction in question, if you see the trash can icon in the upper right corner then you can click the trash can to remove the junction. Two other less advisable methods are [[Creating and editing road segments#Bridge_segments|bridging the segments]] and [[Creating and editing road segments#Drag_together|dragging them together]].
-*If you're lucky, just click Remove Junction on the Edit Panel. The word Remove Junction becomes bold to show it is activated. Click on the junction. Say Yes to the confirming dialog box and, in a few seconds, (if successsful, you'll see Node Removed.  If not and an error message is shown, you'll need to untangle something first.
-*It could be that you are removing a junction from streets that will have conflicts. If you will have a 1 way running directly into an opposite 1 way Waze will block you from removing the junction. Similarly, if you have a segment at the junction that has a Direction of No Entrance, then Wazy won't let you remove the junction.
-</li>
-<li>'''Reconnecting the road into one continuous segement'''
-This can be tricky. You may need to move one set up roads above the other.
-I often find that Waze produces two separate road segments, when you remove a junction.
-To successfully -rejoin the two segments into one continuous segment, without having Waze add a new junction, you need to do the following.  Be sure both segment Edit Road Details are identical.  Same Type, State, City but most of all the segments will need identical settings for Direction, Level, Separating Line, Locked settings.  Use Edit Road Geometry junction to move the end of one segment over the other.  Then, considering the proper flow, link one segment to the other by clicking the 1st road segment as if you were driving and then control-click the 2nd road segment so both are highlighted. Then click Connect Roads by order of selection from the Edit panel.
+If the trash can icon does not appear, it means the junction separates two segments that are not identical. Possibly the road, city, or state name is different. It also may indicate one of the connected segments are locked above your editing rank. Last, the segments may have different routing directions, so check them to be sure they are set correctly.
-You should now have re-connected the previously joined road segments into one continuous road segment.
-</li>
-</ol>
+[[Category:Style guides]]