Is this Overpass query correctly finding a way given two nodes? Can anyone find a counterexample?

Question

I'm using OverpassQL to find a "way" that passes through two consecutive nodes. Here's my query:

[out:json];
(
    way(around:1,x1, y1);
    -
    (
         way(around:1, x1, y1);
         -
         way(around:1, x2, y2);
    );
);
out geom;

I thought of making the intersection between the ways around two points. Since the intersection operation does not exist in OverpassQL I used the subtraction. I'm trying to determine if this query will always return a unique "way" that intersects both of these points. If not, can anyone provide a counterexample where more than one "way" would be returned?

Answer 1

To get the intersection, you can simply combine multiple filters in one query statement:

[out:json];
way(around:1,48.8677584, 2.3139659)
   (around:1,48.8670861, 2.3160717);
out geom;

If you need more control which ways to use for an intersection, you can also have different queries, and intersect the results in a separate step:

[out:json];
way(around:1,48.8677584, 2.3139659) -> .ways1;
way(around:1,48.8670861, 2.3160717) -> .ways2;
way.ways1.ways2;   // intersection
out geom;

I'm trying to determine if this query will always return a unique "way" that intersects both of these points.

No, this will not get you a unique way. Think about a roundabout which has been split into two ways. If you query with both lat/lon values, where the two ways connect, the query will return both ways.

Example returning two ways:

[out:json][date:"2023-10-01T00:00:00Z"];
way(around:1,50.1281949, 1.7851947)
   (around:1,50.1281638, 1.7851656);
out geom;