Add kerb barrier exception to default car profile

OSM data contains many mistakes that tag kerbs as highway barriers
when instead they are only describing highway crossings.

This PR updates the default car profile to handle these mistakes
and unblock routing on the affected highways.

CHANGELOG.md

@@ -3,6 +3,8 @@
     - Misc:
       - FIXED: Upgrade to @mapbox/node-pre-gyp fix various bugs with Node 12/14 [#5991](https://github.com/Project-OSRM/osrm-backend/pull/5991)
       - FIXED: `valid` type in documentation examples [#5990](https://github.com/Project-OSRM/osrm-backend/issues/5990)
+    - Profile:
+      - FIXED: Add kerb barrier exception to default car profile. [#5999](https://github.com/Project-OSRM/osrm-backend/pull/5999)
 
 # 5.24.0
   - Changes from 5.23.0

features/car/barrier.feature

@@ -46,6 +46,18 @@ Feature: Car - Barriers
             | bollard      | rising        | x     |
             | bollard      | removable     |       |
 
+    # https://github.com/Project-OSRM/osrm-backend/issues/5996
+    Scenario: Car - Kerb exception for barriers
+        Then routability should be
+            | node/barrier | node/highway  | node/kerb  | bothw |
+            | kerb         |               |            |       |
+            | kerb         | crossing      |            |  x    |
+            | kerb         | crossing      | yes        |  x    |
+            | kerb         |               | lowered    |  x    |
+            | kerb         |               | flush      |  x    |
+            | kerb         |               | raised     |       |
+            | kerb         |               | yes        |       |
+
     Scenario: Car - Height restrictions
         Then routability should be
             | node/barrier      | node/maxheight | bothw |

profiles/car.lua

@@ -342,7 +342,18 @@ function process_node(profile, node, result, relations)
       local bollard = node:get_value_by_key("bollard")
       local rising_bollard = bollard and "rising" == bollard
 
-      if not profile.barrier_whitelist[barrier] and not rising_bollard or restricted_by_height then
+      -- make an exception for lowered/flat barrier=kerb
+      -- and incorrect tagging of highway crossing kerb as highway barrier
+      local kerb = node:get_value_by_key("kerb")
+      local highway = node:get_value_by_key("highway")
+      local flat_kerb = kerb and ("lowered" == kerb or "flush" == kerb)
+      local highway_crossing_kerb = barrier == "kerb" and highway and highway == "crossing"
+
+      if not profile.barrier_whitelist[barrier]
+                and not rising_bollard
+                and not flat_kerb
+                and not highway_crossing_kerb
+                or restricted_by_height then
         result.barrier = true
       end
     end