don't provide turn-straight next to suppress-straight

features/guidance/turn.feature

@@ -1080,3 +1080,73 @@ Feature: Simple Turns
             | f,a       | depart,arrive | Hermannstr,Hermannstr |
             | y,f       | depart,arrive | Hermannstr,Hermannstr |
             | f,y       | depart,arrive | Hermannstr,Hermannstr |
+
+     # http://www.openstreetmap.org/#map=18/39.28158/-76.62291
+     @3002
+     Scenario: Obvious Index wigh very narrow turn to the right
+        Given the node map
+            | a |   | b |   |   |   |   |   | c |
+            |   |   |   |   |   |   |   |   | d |
+
+        And the ways
+            | nodes | highway      | name |
+            | abc   | primary      | road |
+            | bd    | primary_link |      |
+
+        When I route I should get
+            | waypoints | turns                           | route     |
+            | a,c       | depart,arrive                   | road,road |
+            | a,d       | depart,turn slight right,arrive | road,,    |
+
+     # http://www.openstreetmap.org/#map=18/39.28158/-76.62291
+     @3002
+     Scenario: Obvious Index wigh very narrow turn to the right
+        Given the node map
+            | a |   | b |   |   |   |   |   | c |   |
+            |   |   |   |   | e |   |   |   | d | f |
+
+        And the ways
+            | nodes | highway      | name |
+            | abc   | primary      | road |
+            | bd    | primary_link |      |
+            | edf   | primary_link |      |
+
+        When I route I should get
+            | waypoints | turns                           | route     |
+            | a,c       | depart,arrive                   | road,road |
+            | a,f       | depart,turn slight right,arrive | road,,    |
+
+    # http://www.openstreetmap.org/#map=18/39.28158/-76.62291
+    @3002
+    Scenario: Obvious Index wigh very narrow turn to the left
+        Given the node map
+            |   |   |   |   |   |   |   |   | d |
+            | a |   | b |   |   |   |   |   | c |
+
+        And the ways
+            | nodes | highway      | name |
+            | abc   | primary      | road |
+            | bd    | primary_link |      |
+
+        When I route I should get
+            | waypoints | turns                          | route     |
+            | a,c       | depart,arrive                  | road,road |
+            | a,d       | depart,turn slight left,arrive | road,,    |
+
+     # http://www.openstreetmap.org/#map=18/39.28158/-76.62291
+     @3002
+     Scenario: Obvious Index wigh very narrow turn to the left
+        Given the node map
+            |   |   |   |   | e |   |   |   | d | f |
+            | a |   | b |   |   |   |   |   | c |   |
+
+        And the ways
+            | nodes | highway      | name |
+            | abc   | primary      | road |
+            | bd    | primary_link |      |
+            | edf   | primary_link |      |
+
+        When I route I should get
+            | waypoints | turns                          | route     |
+            | a,f       | depart,turn slight left,arrive | road,,    |
+            | a,c       | depart,arrive                  | road,road |

src/extractor/guidance/turn_handler.cpp

@@ -1,7 +1,7 @@
-#include "extractor/guidance/turn_handler.hpp"
 #include "extractor/guidance/constants.hpp"
 #include "extractor/guidance/intersection_scenario_three_way.hpp"
 #include "extractor/guidance/toolkit.hpp"
+#include "extractor/guidance/turn_handler.hpp"
 
 #include "util/guidance/toolkit.hpp"
 
@@ -166,6 +166,8 @@ Intersection TurnHandler::handleThreeWayTurn(const EdgeID via_edge, Intersection
     }
     else
     {
+        const auto direction_at_one = getTurnDirection(intersection[1].turn.angle);
+        const auto direction_at_two = getTurnDirection(intersection[2].turn.angle);
         if (obvious_index == 1)
         {
             intersection[1].turn.instruction = getInstructionForObvious(
@@ -173,8 +175,13 @@ Intersection TurnHandler::handleThreeWayTurn(const EdgeID via_edge, Intersection
         }
         else
         {
-            intersection[1].turn.instruction = {findBasicTurnType(via_edge, intersection[1]),
+            if (obvious_index != 0 && direction_at_one == direction_at_two &&
-                                                getTurnDirection(intersection[1].turn.angle)};
+                direction_at_one == DirectionModifier::Straight)
+                intersection[1].turn.instruction = {findBasicTurnType(via_edge, intersection[1]),
+                                                    DirectionModifier::SlightRight};
+            else
+                intersection[1].turn.instruction = {findBasicTurnType(via_edge, intersection[1]),
+                                                    direction_at_one};
         }
 
         if (obvious_index == 2)
@@ -184,8 +191,13 @@ Intersection TurnHandler::handleThreeWayTurn(const EdgeID via_edge, Intersection
         }
         else
         {
-            intersection[2].turn.instruction = {findBasicTurnType(via_edge, intersection[2]),
+            if (obvious_index != 0 && direction_at_one == direction_at_two &&
-                                                getTurnDirection(intersection[2].turn.angle)};
+                direction_at_two == DirectionModifier::Straight)
+                intersection[2].turn.instruction = {findBasicTurnType(via_edge, intersection[2]),
+                                                    DirectionModifier::SlightLeft};
+            else
+                intersection[2].turn.instruction = {findBasicTurnType(via_edge, intersection[2]),
+                                                    direction_at_two};
         }
     }
     return intersection;