[Page Update] Junction Box

[subs5]

Hi,
Figured Junction Box 2.0 has been out there long enough that we should update the current wazeopedia page.

Too much of the alphabet inlet/outlet that is gone. Used the original places for the examples except for two where the Junction Box and/or the signage changed since the wiki was written.

Here is my first cut at Junction Box 2.0.

Summary of the minor changes:

1. Changed first picture to JB2.0 format
2. In Function added Turn instruction override as a property
3. Updated the understanding a junction box to the JB 2.0 version with pictures and that TIOs are available
4. Updated Navigational Instructions
5. Updated controlling turns to the JB2.0
6. Removed the statement to use U-turn prevention vice Junction box, especially where one direction is allowed and the other is prohibited vice using micro-doglegs.
7. Update information about the snake and new inlet/outlet designations.

The last page was reviewed by staff prior to publishing so it that is desired, figure it should happen after you refine this draft, even if it is slash and burn and start over again.

[SunnyRaynbows]

@subs5

Here is my first cut at Junction Box 2.0.

Nicely done.
Would it be beneficial to include an image of the ‘snake’ function? I know in some of the discussions we’ve had in Discord, trying to textually describe it has been problematic.

Click for large view - Uploaded with Skitch

[Nagamasa]

I remember I did start updating while JB2 was in progress, but this needs to be removed:

They require more space to store all the data involved.
The routing server takes longer to analyze junction boxes and thus to provide routes through junction boxes.

As well, I would like to expand on the When to Use section a little more in a practical sense:

Junction boxes are well suited for:

• consecutive sets of turns are not allowed or require special guidance (e.g., A Wazer cannot turn left immediately after turning right.)
• when speed of traffic is significantly different between various travel lanes and queues extend for more than 1 node (e.g., A freeway exit has queues extending several nodes back)
• TIO is required in a box, partial box, or other multi-node intersection

[subs5]

@Nagamasa

I remember I did start updating while JB2 was in progress, but this needs to be removed:

They require more space to store all the data involved.
The routing server takes longer to analyze junction boxes and thus to provide routes through junction boxes.

I have removed this statement

@Nagamasa

As well, I would like to expand on the When to Use section a little more in a practical sense:

Junction boxes are well suited for:

• consecutive sets of turns are not allowed or require special guidance (e.g., A Wazer cannot turn left immediately after turning right.)
• when speed of traffic is significantly different between various travel lanes and queues extend for more than 1 node (e.g., A freeway exit has queues extending several nodes back)
• TIO is required in a box, partial box, or other multi-node intersection

I added:
Appropriate times to use a Junction box:

• Have two entrances to same exit path but one route is prohibited so can’t use a simple Turn restriction
• Have u-turn allowed in one direction of an H-intersection, but prohibited in another
• To override u-turn prevention when the cross segment is less than 14 m due to geometry of the intersections
• Traffic build up for a turn lane (or through traffic) backs up through several junctions and affects the timing for the traffic that is moving
• To better collect traffic data on intricate intersections

If there are others that people want let me know.

[subs5]

@SunnyRaynbows

Would it be beneficial to include an image of the ‘snake’ function? I know in some of the discussions we’ve had in Discord, trying to textually describe it has been problematic.

I added your picture and a description of how to use it.

Do people think think we should include the videos from MapSir?
https://youtu.be/wB6Ea6eztKg
https://youtu.be/V4h-t5bOn5o

[SunnyRaynbows]

@subs5

@SunnyRaynbows

Would it be beneficial to include an image of the ‘snake’ function? I know in some of the discussions we’ve had in Discord, trying to textually describe it has been problematic.

I added your picture and a description of how to use it.

Looks good and helpful, thanks!

[anon33958190]

This looks really good! A couple questions on the content:

In the “errors when editing” section, you have preserved the statement about one connection per pair. JB 2.0 actually doesn’t give errors for this. Instead, it forces you to choose which connection is allowed, and if multiple connections between a pair of segments are possible, the snake button shows up, and clicking it actually selects a pair of segments to be allowed (which is why the save counter goes up). If you hit (or keep) the red arrow on a given path and save, that disallows both that specific path and all others between the pair, since the JB can only work with one connection per pair. The page should reflect this new reality.

At the end we should be more specific about what things can’t be edited if a junction box is present. I think there may be a lack of knowledge about how much JB 2.0 has freed up the underlying segments for editing and routine maintenance, which can cause continued reluctance to use JBs in the situations for which they were designed. So that bullet should be amended to read:

*Although most attributes of segments within and connecting to a junction box can still be edited, the presence of a junction box prevents changes to the ID (through cutting, merging or deletion), directionality or partial restrictions of a segment and the position of a junction node within the box. A junction box allows all other changes to segment geometry and attributes as well as the use of real-time closures.

In addition, there’s a dated statement about how JBs do not affect navigational prompts. They do now, because you can set TIOs through them.

[subs5]

@Kartografer

In the “errors when editing” section, you have preserved the statement about one connection per pair. JB 2.0 actually doesn’t give errors for this. Instead, it forces you to choose which connection is allowed, and if multiple connections between a pair of segments are possible, the snake button shows up, and clicking it actually selects a pair of segments to be allowed (which is why the save counter goes up). If you hit (or keep) the red arrow on a given path and save, that disallows both that specific path and all others between the pair, since the JB can only work with one connection per pair. The page should reflect this new reality.

At the end we should be more specific about what things can’t be edited if a junction box is present. I think there may be a lack of knowledge about how much JB 2.0 has freed up the underlying segments for editing and routine maintenance, which can cause continued reluctance to use JBs in the situations for which they were designed. So that bullet should be amended to read:

*Although most attributes of segments within and connecting to a junction box can still be edited, the presence of a junction box prevents changes to the ID (through cutting, merging or deletion), directionality or partial restrictions of a segment and the position of a junction node within the box. A junction box allows all other changes to segment geometry and attributes as well as the use of real-time closures.

In addition, there’s a dated statement about how JBs do not affect navigational prompts. They do now, because you can set TIOs through them.

1. removed that part from errors in editing section
2. Added list of what is not allowed to be edited if involved in a JB
3. removed the Oct 2105 statement about not affecting the navigational prompts.

[ojlaw]

hi alan, it looks like you took out some of the explanation of the 16 connections error. i see why you did, because the visuals were from JB1.0. however, as JB newbie i do find this example helpful-

“Thus, the internal routes from B to G and C to H are available. In this example these u-turns through the junction box are unchecked. If these paths were checked, there would be more than 16 paths through the upper left junction node and the junction box would not save.”

would there be a way to incorporate an example here?
thanks for the consideration. o

[subs5]

@ojlaw

hi alan, it looks like you took out some of the explanation of the 16 connections error. i do find this example helpful-

“Thus, the internal routes from B to G and C to H are available. In this example these u-turns through the junction box are unchecked. If these paths were checked, there would be more than 16 paths through the upper left junction node and the junction box would not save.”

would there be a way to incorporate an example here?
thanks for the consideration. o

I added this explanation to the “Errors when editing” section.
Enabled u-turn turn restriction on a two way segment- Note that having u-turn turn restriction(s) enabled on a two way segment inside of the junction box will increase the amount of paths and can lead to the “The highlighted node cannot have more than 16 connections” error message.

Let me know if this satisfies your comment.

[Nagamasa]

@subs5

• Traffic build up for a turn lane (or through traffic) backs up through several junctions and affects the timing for the traffic that is moving

Can we add a specific point or change the wording to better include freeway ramps/junctions? These are high-traffic, high-impact/reward, rarely edited areas that would be perfect for JBs.

[ojlaw]

that should help. thank you.

[subs5]

@Nagamasa

Can we add a specific point or change the wording to better include freeway ramps/junctions? These are high-traffic, high-impact/reward, rarely edited areas that would be perfect for JBs.

How is this?
Traffic backs up through several junctions from a direct left turn, an at-grade connector (AGC), an exit ramp, or even through travel caught at a traffic light; where the back up adversely affects the timing for the traffic that is moving

[ojlaw]

one question i have and maybe this can be clarified in the “Navigation instructions” section. if a TIO is selected on one of the JB green arrows at what junction node is the TIO applied? maybe you could use your point A to point B (westbound Mill Grove Rd to southbound Idlewild Rd to westbound Indian Trail Fairview Rd) as an example.

thank you. o

[anon33958190]

@ojlaw

one question i have and maybe this can be clarified in the “Navigation instructions” section. if a TIO is selected on one of the JB green arrows at what junction node is the TIO applied? maybe you could use your point A to point B (westbound Mill Grove Rd to southbound Idlewild Rd to westbound Indian Trail Fairview Rd) as an example.

thank you. o

If it works, it is applied at the first node inside the JB

[ojlaw]

@Kartografer

If it works, it is applied at the first node inside the JB

this seems like relevant info to include in the page since the topic is discussed.

thanks for the answer!

[anon33958190]

They don’t override the individual TIOs that may be present later in the JB, and the name of the segment after the first node is used in instructions, which is really not how it should be done, but further development is being done on JB 2.0

[ojlaw]

another question i have is when drawing a JB for Improving data collection purposes, is it necessary to draw the area that is affected by the the traffic back up? maybe this can be addressed in the Editing section

like in this example the left from SB Cicero can take two or three signal cycles to make the left and the left turn traffic backs up to the northern part of the JB https://imgur.com/a/lYqXD or is it sufficient to draw the JB just so it encompasses the junction nodes like this? https://imgur.com/a/ZLqK1

thank you, o

[ojlaw]

@Kartografer

They don’t override the individual TIOs that may be present later in the JB, and the name of the segment after the first node is used in instructions

that also seems like good info to include. just with another possible arrow on the exit of a JB to add a TIO it seems like it would be good to expnd this section to include how adding a TIO at that arrow would affect turn instructions.

may even want to address the the TBTR on the exit arrow too.

thanks for your patience with me. i’m only day 2 into being able to draw real junction boxes so this wiki and discussion are incredibly valuable to me. i’ve paid attention to the subject before now but there is nothing like practical experience.

thanks, o

[anon33958190]

@ojlaw

another question i have is when drawing a JB for Improving data collection purposes, is it necessary to draw the area that is affected by the the traffic back up? maybe this can be addressed in the Editing section

like in this example the left from SB Cicero can take two or three signal cycles to make the left and the left turn traffic backs up to the northern part of the JB https://imgur.com/a/lYqXD or is it sufficient to draw the JB just so it encompasses the junction nodes like this? https://imgur.com/a/ZLqK1

thank you, o

The area of the junction box really doesn’t matter. It’s all about included segments and nodes, because as the page shows, it is basically just combining all the segments and nodes that we see in WME into one single node.