Short way routing - weird unnecessary turns - not enough penalty for turns

[abclop99]

Routing engine

• OsmAnd's in-app offline routing
• Any online routing provider (YOURS, openrouteservice, OSRM, etc.)

Routing Profile

Routing profile: Car
Restriction: None?

Enabled:

• Fuel-efficient way
• Consider temporary limitations
• Minimal distance to recalculate route: 120m
• In case of reverse direction

Start and end points

An example route on openstreetmap.org.

Example route on osmand.net

Any route that goes through that intersection in that direction has the same problem.

Actual route

The actual route turns onto Leitrim Road then turns immediately back onto River Road.

It also shows up on osmand.net with "Short way" enabled

Expected route

The route should go straight through the intersection along River Road as on openstreetmap.org.

Also works properly on osmand.net without "Short way" enabled.

Maps you used (online or offline)

• Offline maps offered within the OsmAnd app for download.
  • 2024-11-23 10:30
• Online (tile / raster) maps
  • Whatever is currently on osmand.net

Your Environment

Device : HWBLA
Brand : HUAWEI
Manufacturer : HUAWEI
Model : BLA-L29
Product : BLA-L29
Build : BLA-L29 [10.0.0.159](http://10.0.0.159/)(C605E4R1P3)
Version : 10
App Version : OsmAnd~
Apk Version : 4.8.6 480603

Anything else?

No response

[Sonwon1]

I have seen this behavior more than once with Osmand. It is usually a map problem. I suggest again that the routing algorithm incorporate some common sense to see if the route makes sense.

Google maps does not exhibit this behavior, maybe they have better maps?

[mdykierek]

My guess is - the straight ahead is 60km/h.
The links don't have speed limits and the short section on the right is 80 + maybe traffic lights penalty is too big to make sense there.
I don't know if the routing takes penalty for taking turns, especially left turns (for right hand drive and the other way around for left).

[yuriiurshuliak]

The bug has been confirmed. Here's how you can consistently reproduce the behavior:

1. Build a route in the Car profile using these coordinates:
   • Start: 45.29093, -75.69393
   • End: 45.29246, -75.69411
2. Observe that the route is built correctly when the "Short way" option is not enabled. This aligns with the expected behavior, as seen in this example: Correct Route.
3. Enable the "Short way" option and rebuild the route.
4. Notice that the route now includes unnecessary detours via Leitrim Road and back to River Road, as shown here: Route with Detour.

The issue appears to be specifically linked to the "Short way" routing option.

"Short way" is disabled	"Short way" is enabled

[Sonwon1]

That explains why I see this bug so often. I use the shortest way routing so routing will take more interesting roads.

[vshcherb]

It looks like not enough penalties for turns in shortway somehow. But there is a penalty for traffic signals 5 seconds

[mdykierek]

To be honest, the penalty of 5 seconds for traffic signals is surprisingly low to me. No traffic lights switch every 20 seconds.
The probability of arriving at traffic signals at red would be close to 50%. The time to stay put at red would be close to 50% of the time, too.
I wonder if the left turn at this intersection is allowed in the end. It's probable that there should be no left turn.

[mdykierek]

If someone can confirm the no-left-turn restriction (no street-level available and aerial are inconclusive), I will fix the map.

[RZR-UA]

The very similar old Issue is found: #17641

Technically, we do not consider any penalty for turns in the short_way mode. Ref: GeneralRouter - calculateTurnTime - shortestRoute.

Additionally, penalty_transition could help, but in this case, the difference between secondary and secondary_link is zero (15-15 = 0). Ref: routing.xml lines 759-760 (penalty_transition - short_way).

It seems that short_way's traffic_signals penalty of 5 seconds is useless in this case and should be set to 0.

We're working on the fix and tests.

[mdykierek]

You know your product best, but no penalty for traffic lights... + in the app I see that the mode is called "fuel efficient". Standing at traffic lights in not fuel efficient at all.
The intersection needs "no left turn" anyway. Let me know when I can fix the map (OsmAnd fix confirmed).

[RZR-UA]

@mdykierek, I already saved the OSM data for this intersection for our tests and fixes so that you can safely apply your fixes (fixing traffic_signals direction and "no-left-turn" is a good idea there if it fits the road).

The question about penalties in the "fuel efficient" mode (short_way, actually) is open for discussion. If your car is equipped with a start-stop system, a zero penalty for traffic_signals is reasonable.

If not equipped... Yeah, we could apply the smaller values of turn penalties, but any penalties for the turns might break the whole idea of searching for the shortest way. Imagine you are a cyclist and want to search for the shortest way, literally.

@vshcherb, please share your opinion. Would we try other options and check how the routing tests will be affected?

[mdykierek]

Good points. Yet left turns (assuming right side traffic) are always slower and less safe than straight and right. Always involve yield the opposite traffic. I bet there are lots of variables e.g. should paths (non-public) roads follow the same rules, should profile /e.g. bicycle/ affect these rules? For sure I don't know enough to play the smart guy. Keep the good work!