|Currently, junction boxes require rank 4 or higher to create or edit them.|
- 1 Function
- 2 Improving data collection
- 3 Controlling turns
- 4 Effects In Editor
- 5 Editing
- 6 When to use
The junction box enables a complex intersection, or interchange composed and displayed as multiple segments to be treated by the routing server as a single junction node with multiple inputs and outputs. Considering a complex intersection as a single point has several beneficial properties:
- Traffic speed data for each path through the junction box can be collected separately.
- Turn restrictions can also be separately controlled for each path through the junction box.
- Turn instruction override can also be separately controlled for each path through the junction box.
- Additional beneficial features of a junction box will be listed here as they become available.
For ETA purposes, the routing server does not consider segments wholly within the junction box, but rather treats the junction box as if all the segments which enter or exit the the junction box are connected to at a single junction node.
Junction boxes are considered only by the routing server. Junction boxes have no visibility in the client or on the live map. Junction boxes do not affect the search engine; the origin or destination of route may be contained in a junction box.
Improving data collectionturn delay transition speed data. Take the following intersection for example. It seems at first glance like a pretty simple intersection, but if it usually experiences heavy traffic this intersection could be collecting bad data.
Without the junction box, the traffic from point A to point C is considered to be the same for both the red and the blue cars. The same statistical data is gathered and the average speed skews the ETA for everyone. The turn delay data is only different for the red and blue cars on the one segment before the turn at D, from C to D.
- A ➡ B
- A ➡ E
- A ➡ F
- B ➡ A
- B ➡ E
- B ➡ F
- E ➡ A
- E ➡ B
- E ➡ F
- F ➡ A
- F ➡ B
- F ➡ E
Thus, URs resulting from the inability to distinguish left turn delays from straight through traffic can be dealt with using the junction box.
Understanding inside a junction box
|There are many types of scenarios where a junction box may be indicated, this sample is used just to explain the function of a junction box, and not meant as guidance on where to use them.|
If a junction box is drawn around these intersections (below left), then when considering a route that would traverse a segment within the box, the routing server treats the intersection like one large junction node for the purpose of calculation transition timing AKA turn delays (below right).A route path from point A to point B (westbound Mill Grove Rd to southbound Idlewild Rd to westbound Indian Trail Fairview Rd) is treated as a single transition, even though in actuality it traverses four segments (3 transitions). The green path is the actual junction box route in WME.
Turn instruction override portion of the grey box. Otherwise the junction box has no effect on the navigational prompts.
Looking back at our example path, going from point A to point B (westbound Mill Grove Rd to southbound Idlewild Rd to westbound Indian Trail Fairview Rd), let's analyze how the junction box works with navigation prompts. Our path is considered for routing as one transition, and judging by the angles it would be a straight transition making it a best continuation with no navigation prompt. But as we just said 'junction boxes have no effect on navigational prompts', therefore the actual navigation prompt given for this path (point A to point B) will consider the three junction nodes and produce:
This is to say that the navigational prompts are still controlled by the actual names, types, and angles of the segments within a junction box.
- For more details on how to control navigation instructions, see How Waze determines turn / keep / exit maneuvers.
Where did my turn restriction(s) go?
Turn instruction override on a junction box exitAs mentioned above the junction box's turn restrictions take over for the first junction node's turn restrictions. Therefore if a turn instruction override is added to the junction box's turn restriction at an exit point, then all internal directions are removed and the turn instruction override command is announced at the first junction node with the first named road segment on that route from the junction node. This can cause problems with the audible announcement for both the location and the announced road name, as shown below.
- Moral of this example is don't put the exit left TIO on the junction box, instead just have it on the major highway's turn restriction and it should announce the correct ramp name at the correct location.
Controlling turnsbow-tie configuration.
Take the intersection of (Leesburg Pike & Fairfax Sq/Fashion Blvd, Tysons Corner, VA) as an example where some some turns are not allowed based upon on which street you originally approached from. Additionally U-turns are prevented in both directions.When traveling nwbound on , it appears that you may turn right using the At grade connector (AGC) to or left onto or continue on . If you were already on before or if entered from to , then you are allowed to make either turn or go straight. But if you entered Leesburg Pike from I-495 S regular lanes' Exit 47A ramp, then the left turn is prohibited to Fairfax Sq; you can only turn right or go straight. The left is prohibited by a sign at the ramp.
Effects In EditorJunction boxes can only be edited by editors of at least rank 4. Junction boxes appear in the Waze Map Editor when the Junction Boxes layer is turned on; the three pieces of paper in the far right of the light gray tool bar on top of the editor. Junction boxes appear as a polygon around all the junction nodes of an intersection.
Selecting the junction box causes the left pane to display the junction box properties. The properties show the editor that created the junction box with the date and the editor of the last update to the junction box. If changes are needed to the junction box or segments associated with the junction box, contact the identified editor or other rank 4 or higher editor in your area.The left pane shows potential entry/exit pairs with a check box ticked for each pair enabled for routing. Note that only entry/exit pair paths which are fully visible on screen are displayed. So make sure you can see the whole boundary of the JB to be sure you're getting a full list of entry/exit pair connections in the left pane.
Routes through the junction box that are prohibited by red turn restrictions between segments within the junction box are not considered.
Difficult turns can be set on the junction box's turn restrictions and do affect routing in the server if the user has the appropriate setting selected.
Any green or yellow turn restriction on a junction box can have the difficult turn attribute added for either 24/7 coverage or with time/day/date restrictions. Please refer to the Difficult turn section for editing directions.
Turn restriction user interface orientation
The turn restriction user interface's grey box will move based upon the distance between the junction box and the edge of the WME editing area. If too close too the edge, then the grey box will cover up parts of the JB. To remedy this, move the WME view so that the junction box has enough room to properly display the grey box or zoom out.One way to consider it is that the outside of the WME editing screen is a picture frame and the JB is the picture; you just need enough matting space for the Turn Interface Grey Box to fit between the picture and the frame. Otherwise, the grey box will cover the picture.
Switch route selection
- Select the entry point of the junction box that you want to compare routes on.
- Hover over the appropriate exit turn restriction that you want to select the desired route.
- The switch route selection will appear appear between the restrictions and difficult turn options in the gray turn restriction box.
- Click the forward or back arrow to cycle thru the allowable routes.
If there is only one route available in the junction box then the switch route selectoin will not appear. Note it may take several clicks to get to the desired route. This current interface dramatically cuts down on the number of clicks to get to desired route since the entry and exit points are anchored and routes from the entry point to other exit points are not considered and you can now backtrack to a route that you previously went past.Example of the route selection in a situation where there are some alternate looping routes available. The first picture shows the typical green path for eastbound Franklin St NE as it continues across Rhode Island Ave NE. If the straight path was prohibited by a Jersey barrier and signage, then the editor can select the alternate path of southbound 15th St NE to northeast-bound Rhode Island Ave NE to eastbound Franklin St NE. The second route as shown in the second picture was set up by clicking the Route icon six times and then allowing the junction box's turn restriction.
Overriding U-turn prevention
A junction box will override U-turn prevention if one or more of the junction nodes are inside the junction box. Unless a prohibited turn restriction prohibits both the left turn and one turn for the U-turn.
There are three cases to consider:
- U-turn prevention is properly set up and a junction box is installed over all or part of the intersection. All u-turns previously prevented by the three criteria are now allowed - UNLESS PROHIBITED BY THE JUNCTION BOX
- U-turns are allowed by the intersection's segment geometries but the junction box is able to prevent the u-turn by having its turn restriction prohibited
- A prohibited turn restriction prevents a left turn and a u-turn inside a junction box; the junction box is not able to override the red turn restriction and neither path will show up as an option in the junction box.
After the junction box is set up, the selected pathways through it supersede the segments' turn restrictions on the pathway within it. Therefore, if a segment's turn restriction within the pathway is later changed, that change is ignored and the pathway(s) selected through the box are not affected.
A Junction box is created by selecting Junction box from the draw segments menu (Shortcut key J). Click at one vertex of the junction box. Continue to click at each vertex of the box until the box surrounds all the junction nodes of the intersection. Double click to complete the box. The boundaries of the box cannot be changed once created. If you need to change the shape of the junction box, you must erase it and create it again.
Before creating a junction box at an intersection, make sure that there are no incorrect turn restrictions including u-turns. Routes through the junction box that are prevented by existing turn restrictions cannot be enabled in the junction box.
The routes through a junction box can be edited when it is selected. To select a junction box, click on it.
When the junction box is selected, the left pane will show the potential connection paths through the junction box as illustrated above. Clicking the check box next to each connection path toggles between enabling or disabling routing between the indicated entry/exit pair.
The left pane includes a button to "Select included segments." Clicking this button will select all the segments with both ends in the junction box (these are the segments that are not considered for ETA routing purposes).
The left pane includes a name box and an address. A name can be added to the name box and the address may be edited. However, currently the name and address of a junction box has no effect.
To delete a junction box, select the junction box and click the delete button (Shortcut key Del).
Changes to junction boxes (and adding new junction boxes) require a tile update to affect routing.
Errors when editing
- No roundabouts - Junction boxes do not support roundabouts. Do not create junction boxes over roundabouts.
- Max size - The size of a junction box cannot exceed 1 kilometer. This is a linear 1 km limit north-south or east-west. If you draw an imaginary 3280 ft x 3280 ft (1 km²) box around the junction box, if the junction box pokes out at any point, then it's too big.
Recent testing has shown the size may be closer to 2,800 square feet (870 square meters).
- Two junction node minimum - A junction box must include at least two junction nodes. Two junction nodes within the junction box must be connected by a segment. A junction box with only one junction node cannot be saved.
- No overlapping - A junction node cannot be included in multiple junction boxes.
- Sixteen paths max - No more than 16 controllable entry/exit paths can pass through a single junction node within a junction box. A save error occurs if a junction node has more than 16 connections. This also counts the adjacent connections not displayed in the routing box list that do not cross any of the internal segments like A to G, D to J, etc.
- 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 saving error message.
Adding segments or junction nodes to an intersection to workaround the "one connection for every entry/exit pair" and "no more than 16 connections per node" limitations is not recommended. If such a workaround is required, please consult with your country manager or regional coordinator.
When to use
Junction boxes are suitable only for specific locations where the above-listed functions of junction boxes are required. An example would be to prohibit the U-turn in one direction but allow it in the other such that a 45.93 ft (14 m) center segment is forcing a necking down of the normal flow of a road and micro-doglegs are used to allow the one direction's U-turn. If problems with data collection or turn restrictions are experienced then, a junction box may be used to solve the problem. If problems are easily solved with other features such as turn restrictions, then a junction box should not be used. For routes through H intersections that have one u-turn allowed and one u-turn prevented then use a simple junction box instead of or U-turn penalties and using micro doglegs to break the u-turn prevention in one direction. Existing intersections with micro doglegs or abnormal geometry can be changed to a junction box when being edited for other reasons, but you shouldn't go out hunting to eliminate all of them if they are already working properly.
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 45.93 ft (14 m) due to the geometry of the intersections
- Traffic backs up through multiple junction nodes 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
- To better collect traffic data on intricate intersections
Junction boxes create another limitation that should be considered:
- Segments connected to junction boxes have some attributes that cannot be edited without first deleting the junction box.
Edits not allowed are:
- Direction of travel (two way/one way)
- Turn restrictions that are not in the junction box for segments that extend outside the junction box's boundaries
- Moving the location of a junction node within a junction box
- Edits that change a segment's identification number
- Adding or deleting a junction node inside the junction box
- Adding or deleting a junction node on a segment that extends outside the junction box (ex. You have to delete the junction box to add a parking lot road to a segment that is included in a junction box)
For these reasons, junction boxes should not be used for every intersection.