Distinguish between offramps and sliproads.

CHANGELOG.md

@@ -1,3 +1,10 @@
+# 5.2
+   Changes from 5.2.0 RC2
+
+   - Guidance:
+     - improved handling of sliproads (emit turns instead of 'take the ramp')
+       BREAKING: modifies the file format with new internal identifiers
+
 # 5.2.0 RC1
    Changes from 5.1.0
 

features/guidance/dedicated-turn-roads.feature

@@ -0,0 +1,117 @@
+@routing  @guidance
+Feature: Slipways and Dedicated Turn Lanes
+
+    Background:
+        Given the profile "car"
+        Given a grid size of 5 meters
+
+    Scenario: Turn Instead of Ramp
+        Given the node map
+            |   |   |   |   | e |   |
+            | a | b |   |   | c | d |
+            |   |   |   | h |   |   |
+            |   |   |   |   |   |   |
+            |   |   |   | 1 |   |   |
+            |   |   |   |   |   |   |
+            |   |   |   |   | f |   |
+            |   |   |   |   |   |   |
+            |   |   |   |   | g |   |
+
+        And the ways
+            | nodes | highway    | name   |
+            | abcd  | trunk      | first  |
+            | bhf   | trunk_link |        |
+            | ecfg  | primary    | second |
+
+       When I route I should get
+            | waypoints | route               | turns                           |
+            | a,g       | first,second,second | depart,turn right,arrive        |
+            | a,1       | first,,             | depart,turn slight right,arrive |
+
+    Scenario: Turn Instead of Ramp
+        Given the node map
+            |   |   |   |   | e |   |
+            | a | b |   |   | c | d |
+            |   |   |   | h |   |   |
+            |   |   |   |   |   |   |
+            |   |   |   |   |   |   |
+            |   |   |   |   |   |   |
+            |   |   |   |   | f |   |
+            |   |   |   |   |   |   |
+            |   |   |   |   |   |   |
+            |   |   |   |   | g |   |
+
+        And the ways
+            | nodes | highway       | name   |
+            | abcd  | motorway      | first  |
+            | bhf   | motorway_link |        |
+            | efg   | primary       | second |
+
+       When I route I should get
+            | waypoints | route                | turns                                                 |
+            | a,g       | first,,second,second | depart,off ramp slight right,merge slight left,arrive |
+
+    Scenario: Inner city expressway with on road
+        Given the node map
+            | a | b |   |   |   | c |
+            |   |   |   |   | f |   |
+            |   |   |   |   |   |   |
+            |   |   |   |   |   |   |
+            |   |   |   |   |   |   |
+            |   |   |   |   |   | d |
+            |   |   |   |   |   |   |
+            |   |   |   |   |   |   |
+            |   |   |   |   |   |   |
+            |   |   |   |   |   | e |
+
+        And the ways
+            | nodes | highway      | name  |
+            | abc   | primary      | road  |
+            | bfd   | trunk_link   |       |
+            | cde   | trunk        | trunk |
+
+       When I route I should get
+            | waypoints | route                | turns                    |
+            | a,e       | road,trunk,trunk     | depart,turn right,arrive |
+
+
+    Scenario: Slipway Round U-Turn
+        Given the node map
+            | a |   | f |
+            |   |   |   |
+            | b |   | e |
+            |   |   |   |
+            |   |   |   |
+            |   | g |   |
+            |   |   |   |
+            | c |   | d |
+
+        And the ways
+            | nodes | highway      | name | oneway |
+            | abc   | primary      | road | yes    |
+            | bge   | primary_link |      | yes    |
+            | def   | primary      | road | yes    |
+
+       When I route I should get
+            | waypoints | route          | turns                        |
+            | a,f       | road,road,road | depart,continue uturn,arrive |
+
+    Scenario: Slipway Steep U-Turn
+        Given the node map
+            | a |   | f |
+            |   |   |   |
+            | b |   | e |
+            |   | g |   |
+            |   |   |   |
+            |   |   |   |
+            | c |   | d |
+
+        And the ways
+            | nodes | highway      | name | oneway |
+            | abc   | primary      | road | yes    |
+            | bge   | primary_link |      | yes    |
+            | def   | primary      | road | yes    |
+
+       When I route I should get
+            | waypoints | route          | turns                        |
+            | a,f       | road,road,road | depart,continue uturn,arrive |

include/engine/guidance/assemble_steps.hpp

@@ -12,8 +12,8 @@
 #include "util/bearing.hpp"
 #include "util/coordinate.hpp"
 #include "util/coordinate_calculation.hpp"
-#include "util/guidance/toolkit.hpp"
 #include "util/guidance/entry_class.hpp"
+#include "util/guidance/toolkit.hpp"
 #include "util/typedefs.hpp"
 
 #include <boost/optional.hpp>
@@ -68,9 +68,7 @@ std::vector<RouteStep> assembleSteps(const DataFacadeT &facade,
     StepManeuver maneuver{source_node.location, bearings.first,
                           bearings.second,      extractor::guidance::TurnInstruction::NO_TURN(),
                           WaypointType::Depart, 0};
-    Intersection intersection{
+    Intersection intersection{source_node.location, std::vector<short>({bearings.second}),
-        source_node.location,
-        std::vector<short>({bearings.second}),
                               std::vector<bool>({true}), Intersection::NO_INDEX, 0};
 
     if (leg_data.size() > 0)
@@ -96,6 +94,17 @@ std::vector<RouteStep> assembleSteps(const DataFacadeT &facade,
                 const auto name = facade.GetNameForID(step_name_id);
                 const auto distance = leg_geometry.segment_distances[segment_index];
 
+                steps.push_back(RouteStep{step_name_id,
+                                          name,
+                                          NO_ROTARY_NAME,
+                                          segment_duration / 10.0,
+                                          distance,
+                                          path_point.travel_mode,
+                                          maneuver,
+                                          leg_geometry.FrontIndex(segment_index),
+                                          leg_geometry.BackIndex(segment_index) + 1,
+                                          {intersection}});
+
                 if (leg_data_index + 1 < leg_data.size())
                 {
                     step_name_id = leg_data[leg_data_index + 1].name_id;
@@ -104,26 +113,26 @@ std::vector<RouteStep> assembleSteps(const DataFacadeT &facade,
                 {
                     step_name_id = target_node.name_id;
                 }
-                steps.push_back(RouteStep{
-                    step_name_id, name, NO_ROTARY_NAME, segment_duration / 10.0, distance,
-                    path_point.travel_mode, maneuver, leg_geometry.FrontIndex(segment_index),
-                    leg_geometry.BackIndex(segment_index) + 1, {intersection}});
 
                 bearings = detail::getIntermediateBearings(leg_geometry, segment_index);
                 const auto entry_class = facade.GetEntryClass(path_point.entry_classid);
-                const auto bearing_class = facade.GetBearingClass(facade.GetBearingClassID(path_point.turn_via_node));
+                const auto bearing_class =
-                intersection.in = bearing_class.findMatchingBearing(util::bearing::reverseBearing(bearings.first));
+                    facade.GetBearingClass(facade.GetBearingClassID(path_point.turn_via_node));
+                intersection.in = bearing_class.findMatchingBearing(
+                    util::bearing::reverseBearing(bearings.first));
                 intersection.out = bearing_class.findMatchingBearing(bearings.second);
                 intersection.location = facade.GetCoordinateOfNode(path_point.turn_via_node);
                 intersection.bearings.clear();
-                std::copy(bearing_class.getAvailableBearings().begin(), bearing_class.getAvailableBearings().end(),
+                std::copy(bearing_class.getAvailableBearings().begin(),
+                          bearing_class.getAvailableBearings().end(),
                           std::back_inserter(intersection.bearings));
                 intersection.entry.clear();
                 for (auto idx : util::irange<std::size_t>(0, intersection.bearings.size()))
                 {
                     intersection.entry.push_back(entry_class.allowsEntry(idx));
                 }
-                maneuver = {intersection.location, bearings.first, bearings.second, path_point.turn_instruction, WaypointType::None, 0};
+                maneuver = {intersection.location,       bearings.first,     bearings.second,
+                            path_point.turn_instruction, WaypointType::None, 0};
                 segment_index++;
                 segment_duration = 0;
             }
@@ -131,10 +140,16 @@ std::vector<RouteStep> assembleSteps(const DataFacadeT &facade,
         const auto distance = leg_geometry.segment_distances[segment_index];
         const int duration = segment_duration + target_duration;
         BOOST_ASSERT(duration >= 0);
-        steps.push_back(RouteStep{
+        steps.push_back(RouteStep{step_name_id,
-            step_name_id, facade.GetNameForID(step_name_id), NO_ROTARY_NAME, duration / 10.,
+                                  facade.GetNameForID(step_name_id),
-            distance, target_mode, maneuver, leg_geometry.FrontIndex(segment_index),
+                                  NO_ROTARY_NAME,
-            leg_geometry.BackIndex(segment_index) + 1, {intersection}});
+                                  duration / 10.,
+                                  distance,
+                                  target_mode,
+                                  maneuver,
+                                  leg_geometry.FrontIndex(segment_index),
+                                  leg_geometry.BackIndex(segment_index) + 1,
+                                  {intersection}});
     }
     // In this case the source + target are on the same edge segment
     else
@@ -148,30 +163,41 @@ std::vector<RouteStep> assembleSteps(const DataFacadeT &facade,
         int duration = target_duration - source_duration;
         BOOST_ASSERT(duration >= 0);
 
-        steps.push_back(RouteStep{
+        steps.push_back(RouteStep{source_node.name_id,
-            source_node.name_id, facade.GetNameForID(source_node.name_id), NO_ROTARY_NAME,
+                                  facade.GetNameForID(source_node.name_id),
-            duration / 10., leg_geometry.segment_distances[segment_index], source_mode,
+                                  NO_ROTARY_NAME,
-            std::move(maneuver), leg_geometry.FrontIndex(segment_index),
+                                  duration / 10.,
-            leg_geometry.BackIndex(segment_index) + 1, {intersection}});
+                                  leg_geometry.segment_distances[segment_index],
+                                  source_mode,
+                                  std::move(maneuver),
+                                  leg_geometry.FrontIndex(segment_index),
+                                  leg_geometry.BackIndex(segment_index) + 1,
+                                  {intersection}});
     }
 
     BOOST_ASSERT(segment_index == number_of_segments - 1);
     bearings = detail::getArriveBearings(leg_geometry);
     // This step has length zero, the only reason we need it is the target location
-    maneuver = {intersection.location, bearings.first, bearings.second, extractor::guidance::TurnInstruction::NO_TURN(), WaypointType::Arrive, 0};
+    maneuver = {intersection.location, bearings.first,
+                bearings.second,       extractor::guidance::TurnInstruction::NO_TURN(),
+                WaypointType::Arrive,  0};
     intersection = {
         target_node.location,
         std::vector<short>({static_cast<short>(util::bearing::reverseBearing(bearings.first))}),
         std::vector<bool>({true}), 0, Intersection::NO_INDEX};
 
     BOOST_ASSERT(!leg_geometry.locations.empty());
-    steps.push_back(RouteStep{target_node.name_id, facade.GetNameForID(target_node.name_id),
+    steps.push_back(RouteStep{target_node.name_id,
-                              NO_ROTARY_NAME, ZERO_DURATION, ZERO_DISTANCE, target_mode,
+                              facade.GetNameForID(target_node.name_id),
-                              std::move(maneuver), leg_geometry.locations.size() - 1,
+                              NO_ROTARY_NAME,
+                              ZERO_DURATION,
+                              ZERO_DISTANCE,
+                              target_mode,
+                              std::move(maneuver),
+                              leg_geometry.locations.size() - 1,
                               leg_geometry.locations.size(),
                               {intersection}});
 
-
     BOOST_ASSERT(steps.front().intersections.size() == 1);
     BOOST_ASSERT(steps.front().intersections.front().bearings.size() == 1);
     BOOST_ASSERT(steps.front().intersections.front().entry.size() == 1);

include/extractor/guidance/classification_data.hpp

@@ -47,6 +47,17 @@ inline bool isRampClass(const FunctionalRoadClass road_class)
            road_class == FunctionalRoadClass::TRUNK_LINK;
 }
 
+// Links are usually smaller than ramps, but are sometimes tagged
+// as MOTORWAY_LINK if they exit/enter a motorway/trunk road.
+inline bool isLinkClass(const FunctionalRoadClass road_class)
+{
+    return road_class == FunctionalRoadClass::MOTORWAY_LINK ||
+           road_class == FunctionalRoadClass::TRUNK_LINK ||
+           road_class == FunctionalRoadClass::PRIMARY_LINK ||
+           road_class == FunctionalRoadClass::SECONDARY_LINK ||
+           road_class == FunctionalRoadClass::TERTIARY_LINK;
+}
+
 // TODO augment this with all data required for guidance generation
 struct RoadClassificationData
 {

include/extractor/guidance/constants.hpp

@@ -26,6 +26,8 @@ const double constexpr MAX_ROUNDABOUT_INTERSECTION_RADIUS =  5;
 const double constexpr MAX_ROUNDABOUT_RADIUS = 15; // 30 m diameter as final distinction
 const double constexpr INCREASES_BY_FOURTY_PERCENT = 1.4;
 
+const unsigned constexpr MAX_SLIPROAD_THRESHOLD = 250;
+
 } // namespace guidance
 } // namespace extractor
 } // namespace osrm

include/extractor/guidance/motorway_handler.hpp

@@ -2,6 +2,7 @@
 #define OSRM_EXTRACTOR_GUIDANCE_MOTORWAY_HANDLER_HPP_
 
 #include "extractor/guidance/intersection.hpp"
+#include "extractor/guidance/intersection_generator.hpp"
 #include "extractor/guidance/intersection_handler.hpp"
 #include "extractor/query_node.hpp"
 
@@ -25,7 +26,8 @@ class MotorwayHandler : public IntersectionHandler
     MotorwayHandler(const util::NodeBasedDynamicGraph &node_based_graph,
                     const std::vector<QueryNode> &node_info_list,
                     const util::NameTable &name_table,
-                    const SuffixTable &street_name_suffix_table);
+                    const SuffixTable &street_name_suffix_table,
+                    const IntersectionGenerator &intersection_generator);
     ~MotorwayHandler() override final;
 
     // check whether the handler can actually handle the intersection
@@ -39,10 +41,14 @@ class MotorwayHandler : public IntersectionHandler
                             Intersection intersection) const override final;
 
   private:
+    Intersection handleSliproads(const NodeID intersection_node_id,
+                                 Intersection intersection) const;
     Intersection fromMotorway(const EdgeID via_edge, Intersection intersection) const;
     Intersection fromRamp(const EdgeID via_edge, Intersection intersection) const;
 
     Intersection fallback(Intersection intersection) const;
+
+    const IntersectionGenerator &intersection_generator;
 };
 
 } // namespace guidance

include/extractor/guidance/turn_analysis.hpp

@@ -59,6 +59,9 @@ class TurnAnalysis
     // Utility function, setting basic turn types. Prepares for normal turn handling.
     Intersection
     setTurnTypes(const NodeID from, const EdgeID via_edge, Intersection intersection) const;
+
+    Intersection handleSliproads(const NodeID intersection_node_id,
+                                 Intersection intersection) const;
 }; // class TurnAnalysis
 
 } // namespace guidance

include/extractor/guidance/turn_instruction.hpp

@@ -20,7 +20,6 @@ namespace detail
 const constexpr uint8_t num_direction_modifiers = 8;
 } // detail
 
-
 // direction modifiers based on angle
 namespace DirectionModifier
 {
@@ -54,15 +53,20 @@ const constexpr Enum EnterRotary = 12;                        // Enter a rotary
 const constexpr Enum EnterAndExitRotary = 13;          // Touching a rotary
 const constexpr Enum EnterRoundaboutIntersection = 14; // Entering a small Roundabout
 const constexpr Enum EnterAndExitRoundaboutIntersection = 15; // Touching a roundabout
+
+// Values below here are silent instructions
 const constexpr Enum NoTurn = 16;                // end of segment without turn/middle of a segment
 const constexpr Enum Suppressed = 17;            // location that suppresses a turn
 const constexpr Enum EnterRoundaboutAtExit = 18; // Entering a small Roundabout at a countable exit
 const constexpr Enum ExitRoundabout = 19;        // Exiting a small Roundabout
 const constexpr Enum EnterRotaryAtExit = 20;     // Enter A Rotary at a countable exit
 const constexpr Enum ExitRotary = 21;            // Exit a rotary
-const constexpr Enum EnterRoundaboutIntersectionAtExit = 22;  // Entering a small Roundabout at a countable exit
+const constexpr Enum EnterRoundaboutIntersectionAtExit =
+    22; // Entering a small Roundabout at a countable exit
 const constexpr Enum ExitRoundaboutIntersection = 23; // Exiting a small Roundabout
 const constexpr Enum StayOnRoundabout = 24; // Continue on Either a small or a large Roundabout
+const constexpr Enum Sliproad =
+    25; // Something that looks like a ramp, but is actually just a small sliproad
 }
 
 // turn angle in 1.40625 degree -> 128 == 180 degree
@@ -87,7 +91,8 @@ struct TurnInstruction
         return TurnInstruction(TurnType::NoTurn, DirectionModifier::UTurn);
     }
 
-    static TurnInstruction REMAIN_ROUNDABOUT(const RoundaboutType, const DirectionModifier::Enum modifier)
+    static TurnInstruction REMAIN_ROUNDABOUT(const RoundaboutType,
+                                             const DirectionModifier::Enum modifier)
     {
         return TurnInstruction(TurnType::StayOnRoundabout, modifier);
     }
@@ -104,8 +109,8 @@ struct TurnInstruction
     static TurnInstruction EXIT_ROUNDABOUT(const RoundaboutType roundabout_type,
                                            const DirectionModifier::Enum modifier)
     {
-        const constexpr TurnType::Enum exit_instruction[] = {TurnType::Invalid, TurnType::ExitRoundabout,
+        const constexpr TurnType::Enum exit_instruction[] = {
-                                                       TurnType::ExitRotary,
+            TurnType::Invalid, TurnType::ExitRoundabout, TurnType::ExitRotary,
             TurnType::ExitRoundaboutIntersection};
         return {exit_instruction[static_cast<int>(roundabout_type)], modifier};
     }

include/util/typedefs.hpp

@@ -32,9 +32,9 @@ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 #include <boost/assert.hpp>
 
-#include <limits>
 #include <cstddef>
 #include <cstdint>
+#include <limits>
 
 // OpenStreetMap node ids are higher than 2^32
 OSRM_STRONG_TYPEDEF(std::uint64_t, OSMNodeID)
@@ -56,6 +56,7 @@ using OSMEdgeID_weak = std::uint64_t;
 
 using NodeID = unsigned int;
 using EdgeID = unsigned int;
+using NameID = std::uint32_t;
 using EdgeWeight = int;
 
 using BearingClassID = std::uint32_t;

src/engine/api/json_factory.cpp

@@ -42,7 +42,8 @@ const constexpr char *turn_type_names[] = {
     "on ramp",         "off ramp",   "fork",     "end of road", "notification",
     "roundabout",      "roundabout", "rotary",   "rotary",      "roundabout turn",
     "roundabout turn", "invalid",    "invalid",  "invalid",     "invalid",
-    "invalid",         "invalid",    "invalid",  "invalid",     "invalid"};
+    "invalid",         "invalid",    "invalid",  "invalid",     "invalid",
+    "invalid"};
 
 const constexpr char *waypoint_type_names[] = {"invalid", "arrive", "depart"};
 
@@ -150,20 +151,19 @@ util::json::Object makeStepManeuver(const guidance::StepManeuver &maneuver)
     return step_maneuver;
 }
 
-util::json::Object
+util::json::Object makeIntersection(const guidance::Intersection &intersection)
-makeIntersection(const guidance::Intersection &intersection)
 {
     util::json::Object result;
     util::json::Array bearings;
     util::json::Array entry;
 
     bearings.values.reserve(intersection.bearings.size());
-    std::copy(intersection.bearings.begin(), intersection.bearings.end(), std::back_inserter(bearings.values));
+    std::copy(intersection.bearings.begin(), intersection.bearings.end(),
+              std::back_inserter(bearings.values));
 
     entry.values.reserve(intersection.entry.size());
     std::transform(intersection.entry.begin(), intersection.entry.end(),
-                   std::back_inserter(entry.values), [](const bool has_entry) -> util::json::Value
+                   std::back_inserter(entry.values), [](const bool has_entry) -> util::json::Value {
-                   {
                        if (has_entry)
                            return util::json::True();
                        else

src/engine/guidance/post_processing.cpp

@@ -41,8 +41,8 @@ void print(const std::vector<RouteStep> &steps)
     int segment = 0;
     for (const auto &step : steps)
     {
-        std::cout << "\t[" << ++segment << "]: " << step.maneuver.instruction.type << " "
+        std::cout << "\t[" << ++segment << "]: " << static_cast<int>(step.maneuver.instruction.type)
-                  << step.maneuver.instruction.direction_modifier << "  "
+                  << " " << static_cast<int>(step.maneuver.instruction.direction_modifier) << "  "
                   << static_cast<int>(step.maneuver.waypoint_type) << " Duration: " << step.duration
                   << " Distance: " << step.distance << " Geometry: " << step.geometry_begin << " "
                   << step.geometry_end << " exit: " << step.maneuver.exit
@@ -63,6 +63,37 @@ void print(const std::vector<RouteStep> &steps)
     }
 }
 
+// Compute the angle between two bearings on a normal turn circle
+//
+//      Bearings                      Angles
+//
+//         0                           180
+//   315         45               225       135
+//
+// 270     x       90           270     x      90
+//
+//   225        135               315        45
+//        180                           0
+//
+// A turn from north to north-east offerst bearing 0 and 45 has to be translated
+// into a turn of 135 degrees. The same holdes for 90 - 135 (east to south
+// east).
+// For north, the transformation works by angle = 540 (360 + 180) - exit_bearing
+// % 360;
+// All other cases are handled by first rotating both bearings to an
+// entry_bearing of 0.
+double turn_angle(const double entry_bearing, const double exit_bearing)
+{
+    const double offset = 360 - entry_bearing;
+    const double rotated_exit = [](double bearing, const double offset) {
+        bearing += offset;
+        return bearing > 360 ? bearing - 360 : bearing;
+    }(exit_bearing, offset);
+
+    const auto angle = 540 - rotated_exit;
+    return angle > 360 ? angle - 360 : angle;
+}
+
 RouteStep forwardInto(RouteStep destination, const RouteStep &source)
 {
     // Merge a turn into a silent turn
@@ -232,37 +263,9 @@ void closeOffRoundabout(const bool on_roundabout,
                          propagation_step.maneuver.instruction.type ==
                              TurnType::EnterRoundaboutIntersectionAtExit)
                 {
-                    // Compute the angle between two bearings on a normal turn circle
-                    //
-                    //      Bearings                      Angles
-                    //
-                    //         0                           180
-                    //   315         45               225       135
-                    //
-                    // 270     x       90           270     x      90
-                    //
-                    //   225        135               315        45
-                    //        180                           0
-                    //
-                    // A turn from north to north-east offerst bearing 0 and 45 has to be translated
-                    // into a turn of 135 degrees. The same holdes for 90 - 135 (east to south
-                    // east).
-                    // For north, the transformation works by angle = 540 (360 + 180) - exit_bearing
-                    // % 360;
-                    // All other cases are handled by first rotating both bearings to an
-                    // entry_bearing of 0.
                     BOOST_ASSERT(!propagation_step.intersections.empty());
                     const double angle =
-                        [](const double entry_bearing, const double exit_bearing) {
+                        turn_angle(util::bearing::reverseBearing(
-                            const double offset = 360 - entry_bearing;
-                            const double rotated_exit = [](double bearing, const double offset) {
-                                bearing += offset;
-                                return bearing > 360 ? bearing - 360 : bearing;
-                            }(exit_bearing, offset);
-
-                            const auto angle = 540 - rotated_exit;
-                            return angle > 360 ? angle - 360 : angle;
-                        }(util::bearing::reverseBearing(
                                        entry_intersection.bearings[entry_intersection.in]),
                                    exit_bearing);
 
@@ -417,6 +420,7 @@ void collapseTurnAt(std::vector<RouteStep> &steps,
             }
 
             steps[one_back_index].name = steps[two_back_index].name;
+            steps[one_back_index].name_id = steps[two_back_index].name_id;
             steps[one_back_index].maneuver.instruction.type = TurnType::Continue;
             steps[one_back_index].maneuver.instruction.direction_modifier =
                 DirectionModifier::UTurn;
@@ -580,6 +584,15 @@ std::vector<RouteStep> collapseTurns(std::vector<RouteStep> steps)
                 instruction.direction_modifier == DirectionModifier::Straight);
     };
 
+    // Special case handling: if the phantomnode landed on a sliproad, we
+    // change this into a 'turn' instruction.  Sliproads are small ramps
+    // between roads, not ramps.
+    if (steps.size() >= 3 &&
+        steps[steps.size() - 2].maneuver.instruction.type == TurnType::Sliproad)
+    {
+        steps[steps.size() - 2].maneuver.instruction.type = TurnType::Turn;
+    }
+
     // first and last instructions are waypoints that cannot be collapsed
     for (std::size_t step_index = 2; step_index < steps.size(); ++step_index)
     {
@@ -595,9 +608,39 @@ std::vector<RouteStep> collapseTurns(std::vector<RouteStep> steps)
         const auto two_back_index = getPreviousIndex(one_back_index);
         BOOST_ASSERT(two_back_index < steps.size());
 
+        // Handle sliproads from motorways in urban areas
+        if (one_back_step.maneuver.instruction.type == TurnType::Sliproad)
+        {
+
+            // Handle possible u-turns between highways that look like slip-roads
+            if (steps[two_back_index].name_id == steps[step_index].name_id &&
+                steps[step_index].name_id != INVALID_NAMEID)
+            {
+                steps[one_back_index].maneuver.instruction.type = TurnType::Continue;
+            }
+            else
+            {
+                steps[one_back_index].maneuver.instruction.type = TurnType::Turn;
+            }
+            steps[one_back_index] = elongate(std::move(steps[one_back_index]), steps[step_index]);
+            steps[one_back_index].name_id = steps[step_index].name_id;
+            steps[one_back_index].name = steps[step_index].name;
+
+            const auto exit_intersection = steps[step_index].intersections.front();
+            const auto exit_bearing = exit_intersection.bearings[exit_intersection.out];
+
+            const auto entry_intersection = steps[one_back_index].intersections.front();
+            const auto entry_bearing = entry_intersection.bearings[entry_intersection.in];
+
+            const double angle =
+                turn_angle(util::bearing::reverseBearing(entry_bearing), exit_bearing);
+            steps[one_back_index].maneuver.instruction.direction_modifier =
+                ::osrm::util::guidance::getTurnDirection(angle);
+            invalidateStep(steps[step_index]);
+        }
         // Due to empty segments, we can get name-changes from A->A
         // These have to be handled in post-processing
-        if (isCollapsableInstruction(current_step.maneuver.instruction) &&
+        else if (isCollapsableInstruction(current_step.maneuver.instruction) &&
                  current_step.name == steps[one_back_index].name)
         {
             steps[one_back_index] = elongate(std::move(steps[one_back_index]), steps[step_index]);

src/extractor/guidance/motorway_handler.cpp

@@ -45,8 +45,10 @@ inline bool isRampClass(EdgeID eid, const util::NodeBasedDynamicGraph &node_base
 MotorwayHandler::MotorwayHandler(const util::NodeBasedDynamicGraph &node_based_graph,
                                  const std::vector<QueryNode> &node_info_list,
                                  const util::NameTable &name_table,
-                                 const SuffixTable &street_name_suffix_table)
+                                 const SuffixTable &street_name_suffix_table,
-    : IntersectionHandler(node_based_graph, node_info_list, name_table, street_name_suffix_table)
+                                 const IntersectionGenerator &intersection_generator)
+    : IntersectionHandler(node_based_graph, node_info_list, name_table, street_name_suffix_table),
+      intersection_generator(intersection_generator)
 {
 }
 
@@ -251,8 +253,7 @@ Intersection MotorwayHandler::fromMotorway(const EdgeID via_eid, Intersection in
                     else if (road.turn.angle < continue_angle)
                     {
                         road.turn.instruction = {
-                            detail::isRampClass(road.turn.eid, node_based_graph)
+                            detail::isRampClass(road.turn.eid, node_based_graph) ? TurnType::OffRamp
-                                ? TurnType::OffRamp
                                                                                  : TurnType::Turn,
                             (road.turn.angle < 145) ? DirectionModifier::Right
                                                     : DirectionModifier::SlightRight};
@@ -260,8 +261,7 @@ Intersection MotorwayHandler::fromMotorway(const EdgeID via_eid, Intersection in
                     else if (road.turn.angle > continue_angle)
                     {
                         road.turn.instruction = {
-                            detail::isRampClass(road.turn.eid, node_based_graph)
+                            detail::isRampClass(road.turn.eid, node_based_graph) ? TurnType::OffRamp
-                                ? TurnType::OffRamp
                                                                                  : TurnType::Turn,
                             (road.turn.angle > 215) ? DirectionModifier::Left
                                                     : DirectionModifier::SlightLeft};

src/extractor/guidance/turn_analysis.cpp

@@ -11,8 +11,8 @@
 #include <limits>
 #include <map>
 #include <set>
-#include <unordered_set>
 #include <unordered_map>
+#include <unordered_set>
 
 using osrm::util::guidance::getTurnDirection;
 
@@ -42,8 +42,16 @@ TurnAnalysis::TurnAnalysis(const util::NodeBasedDynamicGraph &node_based_graph,
                                                                  barrier_nodes,
                                                                  node_info_list,
                                                                  compressed_edge_container),
-      roundabout_handler(node_based_graph, node_info_list, compressed_edge_container, name_table, street_name_suffix_table),
+      roundabout_handler(node_based_graph,
-      motorway_handler(node_based_graph, node_info_list, name_table,street_name_suffix_table),
+                         node_info_list,
+                         compressed_edge_container,
+                         name_table,
+                         street_name_suffix_table),
+      motorway_handler(node_based_graph,
+                       node_info_list,
+                       name_table,
+                       street_name_suffix_table,
+                       intersection_generator),
       turn_handler(node_based_graph, node_info_list, name_table, street_name_suffix_table)
 {
 }
@@ -73,6 +81,9 @@ std::vector<TurnOperation> TurnAnalysis::getTurns(const NodeID from_nid, const E
         }
     }
 
+    // Handle sliproads
+    intersection = handleSliproads(via_eid, std::move(intersection));
+
     std::vector<TurnOperation> turns;
     for (auto road : intersection)
         if (road.entry_allowed)
@@ -105,6 +116,88 @@ TurnAnalysis::setTurnTypes(const NodeID from_nid, const EdgeID, Intersection int
     return intersection;
 }
 
+// "Sliproads" occur when we've got a link between two roads (MOTORWAY_LINK, etc), but
+// the two roads are *also* directly connected shortly afterwards.
+// In these cases, we tag the turn-type as "sliproad", and then in post-processing
+// we emit a "turn", instead of "take the ramp"+"merge"
+Intersection TurnAnalysis::handleSliproads(const EdgeID source_edge_id,
+                                           Intersection intersection) const
+{
+
+    auto intersection_node_id = node_based_graph.GetTarget(source_edge_id);
+
+    const auto linkTest = [this](const ConnectedRoad &road) {
+        return isLinkClass(
+                   node_based_graph.GetEdgeData(road.turn.eid).road_classification.road_class) &&
+               road.entry_allowed &&
+               angularDeviation(road.turn.angle, STRAIGHT_ANGLE) < NARROW_TURN_ANGLE;
+    };
+
+    bool hasRamp =
+        std::find_if(intersection.begin(), intersection.end(), linkTest) != intersection.end();
+    if (!hasRamp)
+        return intersection;
+
+    const auto source_edge_data = node_based_graph.GetEdgeData(source_edge_id);
+
+    // Find the continuation of the intersection we're on
+    auto next_road = std::find_if(
+        intersection.begin(), intersection.end(),
+        [this, source_edge_data](const ConnectedRoad &road) {
+            const auto road_edge_data = node_based_graph.GetEdgeData(road.turn.eid);
+            // Test to see if the source edge and the one we're looking at are the same road
+            return road_edge_data.road_classification.road_class ==
+                       source_edge_data.road_classification.road_class &&
+                   road_edge_data.name_id != INVALID_NAME_ID &&
+                   road_edge_data.name_id == source_edge_data.name_id && road.entry_allowed &&
+                   angularDeviation(road.turn.angle, STRAIGHT_ANGLE) < FUZZY_ANGLE_DIFFERENCE;
+        });
+
+    const bool hasNext = next_road != intersection.end();
+
+    if (!hasNext)
+    {
+        return intersection;
+    }
+
+    // Threshold check, if the intersection is too far away, don't bother continuing
+    const auto &next_road_data = node_based_graph.GetEdgeData(next_road->turn.eid);
+    if (next_road_data.distance > MAX_SLIPROAD_THRESHOLD)
+    {
+        return intersection;
+    }
+
+    const auto next_road_next_intersection =
+        intersection_generator(intersection_node_id, next_road->turn.eid);
+
+    std::unordered_set<NameID> target_road_names;
+
+    for (const auto &road : next_road_next_intersection)
+    {
+        const auto &target_data = node_based_graph.GetEdgeData(road.turn.eid);
+        target_road_names.insert(target_data.name_id);
+    }
+
+    for (auto &road : intersection)
+    {
+        if (linkTest(road))
+        {
+            auto target_intersection = intersection_generator(intersection_node_id, road.turn.eid);
+            for (const auto &candidate_road : target_intersection)
+            {
+                const auto &candidate_data = node_based_graph.GetEdgeData(candidate_road.turn.eid);
+                if (target_road_names.count(candidate_data.name_id) > 0)
+                {
+                    road.turn.instruction.type = TurnType::Sliproad;
+                    break;
+                }
+            }
+        }
+    }
+
+    return intersection;
+}
+
 } // namespace guidance
 } // namespace extractor
 } // namespace osrm