Function Classification Continuity
There are instances when the Waze road typ may need to be upgraded to preserve functional classification continuity. This happens
You're doing the routing engine a favor by interpreting what the intended flow of traffic is, as in "this PS is clearly designed to be the primary route between the limited access road and the mH/MH," this meaning you can justify the upgrade the PS to match the mH/MH
Left Turn Lane(LTL)
Left turn lanes should only be mapped in very limited circumstances-
- When the turn lane physically separates from the main road well in advance of the intersection
- When there is a raised curb between the left turn lane and the through lanes for a long distance before the intersection that the driver might overshoot while waiting for a delayed "turn" audible.
- When the area is "busy" enough that the driver may not get any advance warning that a turn is coming up--in which case a left turn lane lets you notify the driver a little earlier
- When there are user complaints (Update Requests) that the audible was too late, or that the map should have shown a left turn lane
When in doubt, leave it out. Each left turn lane complicates the map and adds to your workload when the time comes to check connectivity, direction, name, etc.
Left turn lanes should be mapped as one-way, using the same road type as the through lanes, with no name, and the speed limit should be set to SL of the segment feeding into the left turn lane(unless signed otherwise). Essentially these left turn lanes are the same road as the through road, we are just adding a segment for better turn instruction timing, so they should be mapped using the road type and speed limit of the through road.
In general using geometry is sufficient for the desired turn instructions- keep left instruction entering the turn lane and turn left instruction at the turn. When geometry won't work use TIOs for these instructions.
Add turn restrictions to prevent U-turn(if applicable), right turn, and to the through-lane left turn(to force use of the left turn lane).
[https://wazeopedia.waze.com/wiki/USA/User:Ojlaw/left_turn_lane LTL]
Should the left turn lane be mapped?
First and foremost, the need to have the left turn lane mapped needs to be established. As the driver approaches an intersection, Waze has usually given at least one warning that a turn is imminent, and we can assume that the driver is already looking for turn lanes. For most intersections, that is enough to guide the driver into the proper lane and to turn at the proper time; in other words, it is enough that the two roads intersect without separately mapped turning lanes.
There are only a few situations in which left turn lanes are called for in an intersection:
- When the turn lane physically separates from the main road well in advance of the intersection
- When the turn lane is far enough from the point of intersection on the map (due to the size of the intersection or the angle at which the roads meet) that the driver might overshoot while waiting for a delayed "turn" audible, or that the Waze client might become confused and disrupt navigation
- When the area is "busy" enough that the driver may not get any advance warning that a turn is coming up--in which case a left turn lane lets you notify the driver a little earlier
- When there are user complaints (Update Requests) that the audible was too late, or that the map should have shown a left turn lane
When in doubt, leave it out. Each left turn lane complicates the map and adds to your workload when the time comes to check connectivity, direction, name, etc.
Road type
Essentially these left turn lanes are the same road as the through road, we are just adding a segment for better turn instruction timing, so they should be mapped using the road type as the through road.
- Ex: Street to Minor Highway should be Street type.
- Ex: Minor Highway to Primary Street should be Minor Highway type.
- Ex: Primary Street to Primary Street should be Primary Street type.
Road name
In most cases, checking None for the Street name will be sufficient. Navigation instructions will simply use the name of the next segment to which the left turn lane segment connects.
If there are specific signs at the intersection which are confusing or contrary to the destination road segment name, then a name can be applied to the left turn lane.
Geometry
In general using geometry is sufficient for the desired turn instructions- keep left instruction entering the turn lane and turn left instruction at the turn. When geometry won't work use TIOs for these instructions.
Turn restrictions
Add turn restrictions to the left turn lane segment to prevent U-turn(if applicable) and right turns.
Add turn restrictions to the adjacent through lane segment left turn(to force use of the left turn lane).
Speed Limit
Left turn lanes should be mapped using the speed limit of the through road unless signed otherwise.