Unexpected behaviour of navigate endpoint

[Sevaz]

Hi Graphhopper Team,

I am using the navigate endpoint to get driving direction to use with the Mapbox SDK.
I saw an unexpected beahviour in this query:
http://localhost:8989/navigate/directions/v5/gh/fastest/15.4805824,46.9185026;15.4630814,46.981762?access_token=dummy&alternatives=false&geometries=polyline6&steps=true&bearings=200,10;&language=de&roundabout_exits=true&voice_instructions=true&banner_instructions=true&voice_units=metric

My goal was to enforce the routing to one direction using bearings and I expected that a route is provided in which multiple left or right turns are provided to go back to the destination, that lays in the opposite direction.

What I got is anyway a uturn as first manuever. Moreover the information about the uturn is not passed to the user in form of a banner or voice information (see attached file).

i tried to pass other parameter accepted by Mapbox V5 (like avoid_manouver_radius) but i see no changes in the results.

Graphhopper version: 7.0 Release run locally
Profile: fastest with turn cost=true and uturn cost =360
Query sent through Postman

Am I missing something?
If I try the same with the route endpoint (of course changing the parameters to use the right one) I get the expected behaviour.

Thanks in advance,

Ale

[karussell]

I think this is a bug which could be also present for the Routing API - can you send the request you used for the Routing API? Please create an issue at Github.

[Sevaz]

Hi Karussel,

thanks for the fast answer, here is the query using the route endpoint:
http://localhost:8989/route?point=46.9185026%2C15.4805824&point=46.981762%2C15.4630814&profile=fastest&heading=200

I realised that also with the route endpoint the first manuver is an u-turn, so the behaviour of the navigate endpoint and route endpoint is the same, sorry for my mistake.

I still have two questions:

1. Why with the navigate endpoint the u-turn information is not passed in the voice and banner instructions?
   2)Is there a way to enforce not doing an u-turn as fist manouver? I tried using pass_through, heading penality and uturn cost as high as 1000 but it does not seem to make any effect.

I did an extra check passing an intermidiate waypoint (here the queries
navigate: http://localhost:8989/navigate/directions/v5/gh/fastest/15.4805824,46.9185026;15.478517,46.916597;15.4630814,46.981762?access_token=dummy&alternatives=false&geometries=polyline6&steps=true&bearings=200,10;;&language=de&roundabout_exits=true&voice_instructions=true&banner_instructions=true&voice_units=metric
route: http://localhost:8989/route?point=46.9185026%2C15.4805824&point=46.916597%2C15.478517&point=46.981762%2C15.4630814&profile=fastest&heading=200&heading_penality=1000&pass_through=true)

an I observed that in this case the u-turn at the intermidiate point is correctly avoided, so it seems something is strange if the u-turn is in the first manouver.

Thanks in advance,

Ale

P.S: should I post it anyway as issue to Github?

[karussell]

If the heading is 200 (pointing south-west) why would you expect the first instruction should be a U-turn?

But still I think we do not support the U-turn instruction as first instruction e.g. for

/route?point=46.92071%2C15.482472&point=46.920424%2C15.482622&profile=car&heading=0&ch.disable=true

I.e. although heading says “go north” the route starts with “go south” and no U-turn instruction is shown.

[Sevaz]

I was expecting that the route goes south and at the first occasion (left or right side road), the route continues to a side road to go north withouth an u-turn as I penalised u-turns with an extreme cost (uturn_cost =1000), as in the example in the screenshot (note: i used a waypoint to demonstarte the route that I was expecting)

If U-turns are not supported as first instruction, I can understand why it happens.
In my opinion I think anyway that the routing should avoid u-turn as first instruction as they do not make lot of sense and are not feasible for most road vehicles.