"Stay on" when continuing on the same road

[1ec5]

Along the same lines as #30, it would be nice if we could say "Keep left to stay on Main St" if Main St. is the street both before and after the fork in the road.

/cc @freenerd @bsudekum @mayagao

[willwhite]

Isn't this the purpose of the continue maneuver type? If not, what is the continue maneuver type for?

The OSRM docs say:

continue | Turn in direction of modifier to stay on the same road

[willwhite]

I'm perplexed by the continue maneuver. Based on what the docs say about "staying on the same road", I'd expect both of these to be continue because they both involve staying on the same road:

• Continue left onto South Airport Boulevard
  • Confusing because this feels like a left turn
  • Ideal instruction would be "Turn left to stay on South Airport Boulevard"
• Keep right at the fork onto I 395
  • Confusing because this is staying on the same road (I'm already on I 395)
  • Ideal instruction would be "Keep right at the fork to stay on I 395"

Does continue make sense as a maneuver type or is it a flag that belongs on all other maneuver types to indicate when a road is staying the same?

/cc @MoKob

[willwhite]

Here's another example:

• We get a "Continue right onto Marsh Road"
• Then we get a "Turn left onto Marsh Road"

Why is the first one a continue and second a turn?

[willwhite]

Why is the first one a continue and second a turn?

This is a bug that should be fixed in Project-OSRM/osrm-backend#4400, but is not yet deployed.

Per voice with @daniel-j-h, the next action is to adjust the phrasing in our continue instructions to be more smooth. For example, instead of Continue slightly right onto {way_name} it should be Turn slightly right to stay on {way_name}.

This is immediately actionable and we should do this now.

However, I don't see how this will address the original fork case described in the OP. fork and continue are both maneuver types, but you can have a fork that continues. How we do handle that case? This leads me back to my original question:

Does continue make sense as a maneuver type or is it a flag that belongs on all other maneuver types to indicate when a road is staying the same?

This would allow any instruction to be rephrased with "stay on" instead of "onto" which is confusing when you're already on the road in question.

[willwhite]

Here's an example of a fork instruction where the name is staying the same:

https://www.mapbox.com/get-directions/#16/36.9879/-122.0236?coordinates=-122.022312,36.989434;-122.02360473016304,36.987874443471256

Since this isn't a continue, I'm not sure we have enough information to make this instruction read "Keep right at the fork to stay on CA 1".

[willwhite]

Next action is to improve whatever we can by rephrasing continue instructions to use "stay on" language.

Unless, I'm missing something we might need some fixes upstream in OSRM in order to support fork instructions that continue on the same road.