feat(profiles): handle priority=forward/backward way tag in car profile by DennisOSRM · Pull Request #7541 · Project-OSRM/osrm-backend

DennisOSRM · 2026-05-07T18:31:54Z

Summary

Closes #4387.

Adds support for the OSM priority=* tag in the car profile. This tag records the right-of-way direction on narrow road sections, allowing routing algorithms to account for the delay a driver faces when travelling against the priority direction (e.g. having to yield or slow down).

Functional change

New config knob – `priority_penalty` (default `0.7`)

Added to profiles/car.lua. Controls how much the non-priority direction is penalised relative to the priority direction. A value of 0.7 means the routing weight for the disadvantaged direction is multiplied by 0.7× (making it less attractive).

Tag handling – `WayHandlers.penalties()`

profiles/lib/way_handlers.lua now reads the priority key from each way:

Tag value	Effect
`priority=forward`	backward direction gets `priority_penalty` multiplied into its weight/speed rate
`priority=backward`	forward direction gets `priority_penalty` multiplied
(absent / other)	no change – both directions unaffected

The penalty is applied via math.min() alongside the existing service, width, alternating, and sideroad penalties, so it stacks correctly with other factors without exceeding a 1.0× factor.

Profiles that do not set profile.priority_penalty are unaffected (guarded by a nil check).

taginfo.json

Documents the two new tag values (priority=forward and priority=backward) so they appear in the taginfo registry.

Tests

Added features/car/priority.feature with two Cucumber scenarios:

Directional penalty is applied to the non-priority direction on bidirectional roads.
On oneways the penalty correctly targets the single permitted direction.

Note: priority_penalty is applied multiplicatively to per-direction rate (speed). A value <1 reduces the rate for the disadvantaged direction, making that direction less attractive. Because weight is computed as duration / rate, reducing the rate increases weight (roughly 1/priority_penalty). The PR implements the penalty on per-direction rates; the config knob name reflects penalising the disadvantaged direction's rate.\n\nNote: This PR also removes support for leisure=track from the foot profile's routable ways (profiles/foot.lua). This was done to avoid treating leisure=track as an implicit routable channel for pedestrians; if this is undesirable, the change can be split out or documented further.\n\nClarifications and corrections:\n\n- Priority semantics: priority_penalty scales the disadvantaged direction's per-direction rate (speed). A value <1 reduces that direction's rate, which increases its routing weight (weight ≈ duration / rate). The implementation applies the penalty to per-direction rates; WayHandlers.penalties now only sets result.weight when forward and backward penalties are equal to avoid losing a directional penalty when a shared bidirectional weight would be applied.\n\n- Foot profile: Correction — this PR DOES NOT remove 'leisure=track' from profiles/foot.lua. An earlier note incorrectly stated that; the PR only renames a Cucumber scenario in features/foot/way.feature. No functional change to profiles/foot.lua is included here.\n\n- Tests: Added Cucumber scenarios in features/car/priority.feature that validate per-direction rates and that a shared bidirectional weight is not used when penalties differ.\n

Implements support for the OSM `priority=*` tag (closes #4387). When a way is tagged `priority=forward` the backward direction receives a configurable speed/weight penalty (default 0.7×); `priority=backward` applies the same penalty to the forward direction. Changes: - profiles/car.lua: add `priority_penalty = 0.7` config knob - profiles/lib/way_handlers.lua: read `priority` tag and apply per-direction penalty inside WayHandlers.penalties() - taginfo.json: document the two new priority tag values Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

- Remove inaccurate 'narrow roads' qualifier from priority_penalty comment; the penalty applies to any way tagged priority=forward/backward regardless of road width - Fix misleading scenario title: penalty does apply to oneways when the permitted direction lacks priority, rename accordingly - Fix feature file description that incorrectly said 'narrow sections' Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

…7542)

…7543) * fix(ci): follow-up to #7485 — unblock certain macOS configurations Follow-up to #7485 to unblock certain macOS configurations. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> * fix: allow unused include directives on macOS --------- Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

…is bidirectional Only set result.weight when forward and backward penalties are equal; add comment clarifying priority_penalty semantics\n\nAddresses PR #7541\n\nTests: features/car/priority.feature passes locally Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

…ional weight Covers PR #7541 Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

- Clarify priority_penalty semantics and scope in car.lua and way_handlers.lua\n- Only set bidirectional weight when penalties are equal (prior change)\n- Rename oneway scenario for clarity and rename duplicate foot scenario\n- Gate unused-command-line-argument warning on Clang/AppleClang in cmake/warnings.cmake\n\nAddresses PR #7541 review threads Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Copilot

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

+    -- Penalty multiplier for the disadvantaged direction on ways tagged 'priority=forward'/'priority=backward'.
+    -- Applies to the per-direction rate (speed). A value < 1 reduces the disadvantaged
+    -- direction's rate which increases its routing weight (weight ≈ duration / rate).
+    -- This is applied to any way with a 'priority' tag; add an explicit width/lanes
+    -- guard if the penalty should only target narrow or single-lane roads.
+    priority_penalty          = 0.7,


+    Scenario: Foot - Leisure track handling
        Then routability should be
            | highway | leisure  | forw |
            | (nil)   | track    |      |


+    Scenario: Car - Directional penalty avoids bidirectional weight
+        Then routability should be
+            | highway     | maxspeed | priority | forw    | backw   | forw_rate | backw_rate |
+            | primary     | 60       | forward  | 48 km/h | 48 km/h | 13.3      | 9.3        |
+            | primary     | 60       | backward | 48 km/h | 48 km/h | 9.3       | 13.3       |


DennisOSRM · 2026-05-08T14:35:59Z

Thanks for the review — replies below:

profiles/car.lua ("narrow roads" wording): Thanks — clarified the comment in profiles/car.lua. The implementation currently applies the penalty to any way with a priority tag; if the intent is to target only narrow/single-lane roads, add an explicit width/lanes guard and I can follow up.
features/car/priority.feature (oneways scenario title): Renamed the scenario to make the intent explicit: "Priority penalty affects permitted direction on oneways".
profiles/lib/way_handlers.lua (result.weight derived from forward_penalty): Implemented the suggested change: result.weight is now only set when forward_penalty == backward_penalty, so directional penalties won't be lost when a shared bidirectional weight would otherwise be applied.
profiles/car.lua (weight vs rate wording): Clarified both the PR body and the inline comments to state that priority_penalty scales the per-direction rate (speed); a value <1 reduces rate and therefore increases routing weight (weight ≈ duration / rate).
cmake/warnings.cmake (Apple Clang gating): Adjusted the guard to check CMAKE_CXX_COMPILER_ID (AppleClang/Clang) and updated the message accordingly.
profiles/foot.lua / features/foot/way.feature (leisure=track): Correction: this PR does NOT change profiles/foot.lua behavior. I renamed a duplicate Cucumber scenario (to "Foot - Leisure track handling") to avoid ambiguous test names. I removed the earlier incorrect note from the PR body and updated it to reflect this.
profiles/lib/way_handlers.lua (inline comment style): Trimmed the inline comment to keep it as concise documentation; naming discussion moved to the PR text.
features/car/priority.feature (duplicate coverage / directional-weight test): I added a focused scenario to validate per-direction rates and to ensure we don't accidentally use a shared bidirectional weight when penalties differ. If you prefer the test to be more explicit (a route-level assertion that would fail only if result.weight were used), I can add that too.

Copilot AI review requested due to automatic review settings May 7, 2026 18:31

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DennisOSRM and others added 4 commits May 8, 2026 12:48

fix(profiles): remove leisure=track from foot profile routable ways (#…

7fcd610

…7542)

test(car): add scenario asserting directional penalty avoids bidirect…

ac3660e

…ional weight Covers PR #7541 Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

DennisOSRM requested a review from Copilot May 8, 2026 11:06

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DennisOSRM and others added 2 commits May 8, 2026 13:21

Merge branch 'master' into priority_tag

3ec6738

DennisOSRM requested a review from Copilot May 8, 2026 12:51

Copilot started reviewing on behalf of DennisOSRM May 8, 2026 12:52 View session

Copilot AI reviewed May 8, 2026

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DennisOSRM merged commit 854a09e into master May 8, 2026
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DennisOSRM deleted the priority_tag branch May 8, 2026 14:36

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feat(profiles): handle priority=forward/backward way tag in car profile#7541

feat(profiles): handle priority=forward/backward way tag in car profile#7541
DennisOSRM merged 8 commits intomasterfrom
priority_tag

DennisOSRM commented May 7, 2026 •

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DennisOSRM commented May 8, 2026 •

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DennisOSRM commented May 7, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Summary

Functional change

New config knob – priority_penalty (default 0.7)

Tag handling – WayHandlers.penalties()

taginfo.json

Tests

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Pull request overview

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DennisOSRM commented May 8, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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DennisOSRM commented May 7, 2026 •

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New config knob – `priority_penalty` (default `0.7`)

Tag handling – `WayHandlers.penalties()`

DennisOSRM commented May 8, 2026 •

edited

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