Improve LFRCNP handling for cross-provider OpenLR decoding - #19
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Add exception for SlipRoad (FOW=6) edges in bounded_astar's LFRCNP filter. This handles cross-provider decoding where motorway_link, trunk_link, etc. are mapped to FRC3 in OSM but need to be traversable when connecting to/from motorways (FRC0/FRC1). The +1 FRC tolerance is retained for general cross-provider mismatches where HERE's classification doesn't align exactly with OSM highway tags. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
Previously, the +1 FRC tolerance was applied uniformly, allowing residential roads (FRC4) to be used even when LFRCNP=3 indicated the path should stay on higher-class roads. This caused detours through residential areas when direct primary road paths existed. Changes: - Two-pass approach: try strict LFRCNP first, fall back to +1 only if no path found. This prevents mixing valid FRC with invalid. - Apply same LFRCNP threshold to both end candidate filtering AND middle path A* search (no separate fallback that could leak). - SlipRoads (links) still allowed regardless of FRC to bridge classes. - Length tolerance: use max() instead of min() for upper bound, giving short segments more slack for cross-provider geometry diffs. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
The try_same_edge_solution shortcut was bypassing LFRCNP filtering, allowing a residential edge to be chosen when LFRCNP forbade it. Changes: - Add max_frc parameter to try_same_edge_solution - Check edge FRC against LFRCNP (SlipRoads always allowed) - Defer relaxed same-edge fallback until after strict A* search fails Order of attempts: 1. Same-edge with strict LFRCNP 2. Multi-edge A* with strict LFRCNP 3. Same-edge with relaxed LFRCNP (+1) 4. Multi-edge A* with relaxed LFRCNP (+1) This ensures same-edge shortcuts cannot bypass the LFRCNP constraint, and relaxed solutions are only used when no strict path exists. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
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Summary
Fixes issues where the decoder would take detours through low-importance roads (e.g., residential) even when LFRCNP indicated the path should stay on higher-class roads.
Problem
When decoding HERE OpenLR onto OSM networks, the
+1FRC tolerance was applied uniformly, allowing residential roads (FRC4) to be used when LFRCNP=3. This caused the decoder to prefer closer but incorrect candidates, resulting in longer paths through residential areas instead of direct routes on primary roads.Solution
Two-pass LFRCNP approach: Try strict LFRCNP first, only fall back to +1 tolerance if no path exists.
Order of attempts:
This prevents mixing valid FRC edges with invalid ones while still allowing consistent cross-provider FRC shifts when necessary.
Additional changes
Test results
🤖 Generated with Claude Code