Organic Maps: Fixing Incorrect Lane Guidance

Let's dive into a discussion about routing lanes and addressing instances where Organic Maps might be giving us the wrong lane recommendations. We'll use a specific example to illustrate the issue and explore potential solutions. So, buckle up, guys, and let's get started!

The Problem: Lane Recommendations Gone Wrong

Imagine you're approaching a crossing like the one shown below:

You can also check it out on OpenStreetMap: https://www.openstreetmap.org/way/37828105

The road is tagged with turn:lanes="through|through;right|right". Now, you want to make a right turn. The Organic Maps routing engine interprets this turn as CarDirection::TurnSlightRight. The lane recommendation algorithm then kicks in with a specific logic:

1. It first attempts to strictly map lane ways to car directions. For example, CarDirection::TurnRight should correspond to LaneWay::Right, and CarDirection::TurnSlightRight should correspond to LaneWay::SlightRight.
2. If a strict mapping isn't possible, it tries a more flexible approach. In this case, CarDirection::TurnSlightRight could map to {LaneWay::SlightRight, LaneWay::Through, LaneWay::Right}.

https://github.com/organicmaps/organicmaps/blob/b7a01993d6d03792d7bae8fbb846c50e3b7c61f6/libs/routing/turns.cpp#L253-L270

The problem arises because all three lanes end up being marked as active, and the through lane gets recommended due to its higher priority (it appears earlier in the list). This isn't ideal, as it can lead to incorrect lane guidance.

The Question: Right Turn or Slight Right?

This brings us to the core question: Is the original mapping in this specific example correct? Should this turn be mapped as a slight_right? The OSM wiki provides an example suggesting that it should be mapped as slight_right:

However, this example seems to be geared toward highways, while our example is located within a city. This might suggest that the current mapping as right is actually correct. It's a bit of a head-scratcher, isn't it?

We need to carefully consider how to handle these ambiguous cases to ensure accurate lane recommendations. It's all about making sure Organic Maps gives you the best possible guidance when you're navigating those tricky intersections. The current logic needs refinement to make the routing experience seamless and intuitive. A more nuanced approach, considering factors like road type and context, is essential for improving lane recommendation accuracy.

A Potential Solution: Prioritizing the Right Lanes

To address this issue, a change was implemented to map CarDirection::TurnSlightRight to {LaneWay::SlightRight, LaneWay::Right}, effectively removing LaneWay::Through from the options. This was done in this PR: https://github.com/organicmaps/organicmaps/pull/11026

The result of this change is that the right lanes are now correctly highlighted:

This approach ensures that users are guided towards the appropriate lanes when making slight right turns, reducing confusion and improving overall navigation. By fine-tuning the lane mapping logic, we can enhance the reliability and usability of Organic Maps, providing a smoother and more accurate routing experience for everyone.

Digging Deeper: Refining the Lane Recommendation Logic

So, what else can we do to make things even better? Well, one idea is to look at the angle of the turn. Is it a super sharp right, or just a gentle nudge to the right? Maybe we can use some fancy math to figure that out and pick the right lane suggestion. We could also think about the speed limit on the road. If you're cruising on a highway, a slight right might be different than a slight right on a tiny street in the city. Little tweaks like that could make a big difference in how accurate our lane suggestions are.

And hey, let's not forget about user feedback! If people are constantly reporting that the lane suggestions are wonky in certain areas, that's a big clue that we need to take a closer look. We could even add a little button in the app that lets people quickly say, "Hey, the lane suggestion here is wrong!" That would give us a ton of data to work with and help us improve things even faster.

The Broader Picture: Making Navigation a Breeze

Ultimately, it's all about making navigation as easy and stress-free as possible. We want people to be able to use Organic Maps and feel confident that they're going the right way. Accurate lane suggestions are a big part of that. When the app tells you exactly which lane you need to be in, it just makes everything smoother and safer. You're not scrambling at the last second to switch lanes, and you can focus on driving. That's the goal, right? A calm, confident, and safe driving experience.

And let's be real, nobody wants to get stuck in the wrong lane and miss their turn. That's just frustrating! So, by constantly tweaking and improving our lane recommendation logic, we're helping people avoid those annoying situations. We're making Organic Maps a more reliable and user-friendly tool for everyone.

Conclusion: Continuing the Journey to Better Routing

In conclusion, addressing incorrect lane recommendations is an ongoing process. By identifying issues, proposing solutions, and continuously refining our algorithms, we can make Organic Maps an even more reliable and user-friendly navigation tool. It's about teamwork, attention to detail, and a shared commitment to providing the best possible experience for our users. So, keep those suggestions coming, and let's work together to make Organic Maps the ultimate navigation companion!