Roundabouts and Slip-Roads

[MotoUKRider]

Hello - Cruiser user here.

I've just updated to v1.7 and found that a Route didn't load - further investigation reveals it boils down to roundabouts and slip-roads as starting points - replicated in several places on a map using duplicate "preferences" on 2 devices, the other using the previous BRouter from GooglePlay Store.

If you attempt to start from a roundabout (ie: a place where fuel/services may be) then it won't "route". The on/off-ramp/slip-road does not route, either. You have to start the Route on the main carriageway or a little back from the roundabout.

See example below: It will "route" on the main A15 towards the Humber Bridge, but not on the entry-ramp, so you have to find a "clear" piece of road.

[MotoUKRider]

Update: a further test suggests that it's only the Start point causing a problem. A Route with a Shaping-Point in the same place was able to route correctly.

[afischerdev]

I've tried to get the fail with your description. And used it with this sample - I always need exact data for producing an error. I have no web server with 1.7.0 lib but in offline generation this is the result.

Seems alright for me. It starts on ramp (near your point). Do I miss something?

PS this also work when I come from the Lidl parking space to bridge.

[MotoUKRider]

Just to clarify, I'm using the Cruiser navigation app (Mapsforge maps) with the latest 1.7 "offline" BRouter on my Android device. If I switch to "online" within the app, BRouter performs as expected. "In browser" BRouter is fine :)

I have since tried other roundabouts/slip-roads around the UK and reproduced the same issue.

[devemux86]

@MotoUKRider

Can you export a small route example in the (offline) GPX navigation gpx format?

Then I can check the parameters sent to the BRouter app and @afischerdev can see what's happening in BRouter.

[afischerdev]

@MotoUKRider I got that. Anyway on my phone this is Cruiser and BRouter last versions:

Still not see the problem. May be you can tell us more about your settings? e.g. your profile - I use car-fast in this sample

[devemux86]

@MotoUKRider @afischerdev

What routing settings do you use?

• Navigation profile
• Route type
• Avoidance options

So we can see what BRouter profile and extra parameters are called.

[MotoUKRider]

Sure, here's a short working route - obviously Cruiser won't let me export a "non" route, but if I move the Start Point to those bad places, it won't "route". Very odd. I can even "Start" in the field away from the road and BRouter snaps to the road nearby, so it's working up to a point - but just doesn't like roundabouts/slip-roads :(

Cruiser: "Car" Navigation Profile, "Fastest" Route Type, no avoidances BRouter: "car-fast" and selecting "motocar_fast" Server-Mode in BRouter

It's about as "stock" as I can get - just the update stopped it working. Bizarre, I know!

cruiser-brouter-issue.zip

[afischerdev]

Same as mem just as it comes out of the box. Download tiles are from today as this is not my area.

[devemux86]

@MotoUKRider thanks for the sample. :+1:

The issue is in Cruiser reader of the BRouter responses. The 1st trkpt contains:

<sym>roundabout_e2</sym>
<type>Via</type>

Usually we expect in the 1st trkpt:

<sym>pass_place</sym>
<type>Via</type>

Is the BRouter response correct or we need to adjust the Cruiser reader?

[afischerdev]

That's it. In my test -0.455417,53.680995;-0.449084,53.695384 I got an unexpected roundabout_e2 at the first point. But when I control the 'old' export with waypoints I get the same result also on first point:

<wpt lat="53.680993" lon="-0.455413"><ele>43</ele><name>Take exit 2</name></wpt>

A beautiful sample.

Who tells us what is the right form?

[devemux86]

cc @0709wiwiwi

It should be valid to have a turn instruction at the 1st point (start) of a route. Mostly it is a simple "straight", but in some cases it can even be a u-turn.

The old format has a different structure. In the new format we use a limited number of tags, we have to fit everything in them.

[0709wiwiwi]

1. Surely this is a rare and rather surprising discovery.
2. The snap to street action causes the start to fall on the roundabout.
3. Roundabout indication locations are where the oncoming road connects to the roundabout.
4. So if you only start at the roundabout itself, the condition 3 is not present.
5. You start on a "crooked" road and so the indication should be "pass_place".
   (Compare with the first (rtept) route(way)point but here it is one that snapped to the nearest road).
6. Where you leave that "crooked" road then, a standard L/R directional indication is expected. But admittedly that expectation may be a bit too high anyway ;-)

By the last Beta the BRouterAPP 1.6.4l-release this issue did and does not occur. And also the GH offline router engine in Cruiser handles this fine. A normal start is so possible at the roundabout. (Confirmed by test). Start location (before the snap to street action) placed at the parking lot of a pharmacy near a roundabout. Start_rotonde_gh.gpx.txt

[devemux86]

For now I will make Cruiser reader more flexible in the next update, so it has no problem reading such responses.

• https://github.com/devemux86/cruiser/discussions/150

[afischerdev]

@0709wiwiwi I also tested the GH router inside Cruiser with our sample above. My result is: Shows GH also delivers roundabout logic. When I export this to GPX I get a similar result as you in your gpx file. The start point is inside but no turn instruction. But this is not a fall back from roundabout to 'normal' turn instruction logic. For me it seems to be the conflict between start point vs. voice hint goes to the start point. And on a fall back I would expect a right on 1. exit and and a left on 2. exit.

When you export this as a kurviger file you have the 'take exit 2' inside at position index 0.

@devemux86 Yes, we have a different structure now. But the output format changes not the routing logic. All other export formats accept a turn instruction on the first point.

[afischerdev]

Anyway, we have a problem in this example:

The result of the roundabout is RNDB2 for right-hand traffic. It should be RNLB2 on the left side.

[0709wiwiwi]

Alex, Surprising was the modified behavior compared to the Beta. What is important is that a routing start up is not blocked.

Cruiser and Locus handle imports of trkpt sym with type Via_Shaping slightly different. In Cruiser any trkpt sym turn with a type Via or Shaping is accepted as routing reference. In Locus only the sym pass-place is usefully to be used as via point routing reference.

[devemux86]

For now I will make Cruiser reader more flexible in the next update, so it has no problem reading such responses.

- https://github.com/devemux86/cruiser/discussions/150

It works properly in Cruiser 3.0.19.

[quaelnix]

@devemux86, is there anything left to do, or can we close this?

[devemux86]

@quaelnix thanks for asking, I have already updated the reader in Cruiser.

So we can close this issue, as a turn instruction in the first trkpt is valid.