diff --git a/src/ext-test/java/org/opentripplanner/ext/siri/SiriTimetableSnapshotSourceTest.java b/src/ext-test/java/org/opentripplanner/ext/siri/SiriTimetableSnapshotSourceTest.java
index e058958d350..b34f47205b6 100644
--- a/src/ext-test/java/org/opentripplanner/ext/siri/SiriTimetableSnapshotSourceTest.java
+++ b/src/ext-test/java/org/opentripplanner/ext/siri/SiriTimetableSnapshotSourceTest.java
@@ -37,15 +37,18 @@ void testCancelTrip() {
   }
 
   @Test
-  void testAddJourney() {
+  void testAddJourneyWithExistingRoute() {
     var env = RealtimeTestEnvironment.siri();
 
+    Route route = env.getTransitService().getRouteForId(env.route1Id);
+    int numPatternForRoute = env.getTransitService().getPatternsForRoute(route).size();
+
     String newJourneyId = "newJourney";
     var updates = new SiriEtBuilder(env.getDateTimeHelper())
       .withEstimatedVehicleJourneyCode(newJourneyId)
       .withIsExtraJourney(true)
       .withOperatorRef(env.operator1Id.getId())
-      .withLineRef(env.route1Id.getId())
+      .withLineRef(route.getId().getId())
       .withRecordedCalls(builder -> builder.call(env.stopC1).departAimedActual("00:01", "00:02"))
       .withEstimatedCalls(builder -> builder.call(env.stopD1).arriveAimedExpected("00:03", "00:04"))
       .buildEstimatedTimetableDeliveries();
@@ -69,6 +72,11 @@ void testAddJourney() {
         new TripIdAndServiceDate(tripId, SERVICE_DATE)
       )
     );
+    assertEquals(
+      numPatternForRoute + 1,
+      transitService.getPatternsForRoute(route).size(),
+      "The added trip should use a new pattern for this route"
+    );
   }
 
   @Test
@@ -99,7 +107,7 @@ void testAddJourneyWithNewRoute() {
     FeedScopedId newRouteId = TransitModelForTest.id(newRouteRef);
     Route newRoute = transitService.getRouteForId(newRouteId);
     assertNotNull(newRoute);
-    assertNotNull(transitService.getPatternsForRoute(newRoute));
+    assertEquals(1, transitService.getPatternsForRoute(newRoute).size());
   }
 
   @Test
diff --git a/src/main/java/org/opentripplanner/model/TimetableSnapshot.java b/src/main/java/org/opentripplanner/model/TimetableSnapshot.java
index 1ec438c17bd..e6dcdd2eee1 100644
--- a/src/main/java/org/opentripplanner/model/TimetableSnapshot.java
+++ b/src/main/java/org/opentripplanner/model/TimetableSnapshot.java
@@ -253,7 +253,6 @@ public TripPattern getRealTimeAddedPatternForTrip(Trip trip) {
   /**
    * Return the trip patterns created by the updater for the given route.
    */
-  @Nullable
   public Collection<TripPattern> getRealTimeAddedPatternForRoute(Route route) {
     return realTimeAddedPatternsForRoute.get(route);
   }
diff --git a/src/main/java/org/opentripplanner/transit/service/DefaultTransitService.java b/src/main/java/org/opentripplanner/transit/service/DefaultTransitService.java
index 762c04c76a7..7a8f420cef1 100644
--- a/src/main/java/org/opentripplanner/transit/service/DefaultTransitService.java
+++ b/src/main/java/org/opentripplanner/transit/service/DefaultTransitService.java
@@ -341,14 +341,17 @@ public TripPattern getPatternForTrip(Trip trip, LocalDate serviceDate) {
   @Override
   public Collection<TripPattern> getPatternsForRoute(Route route) {
     OTPRequestTimeoutException.checkForTimeout();
+    Collection<TripPattern> tripPatterns = new HashSet<>(
+      transitModelIndex.getPatternsForRoute().get(route)
+    );
     TimetableSnapshot currentSnapshot = lazyGetTimeTableSnapShot();
     if (currentSnapshot != null) {
-      Collection<TripPattern> tripPatterns = currentSnapshot.getRealTimeAddedPatternForRoute(route);
-      if (!tripPatterns.isEmpty()) {
-        return tripPatterns;
-      }
+      Collection<TripPattern> realTimeAddedPatternForRoute = currentSnapshot.getRealTimeAddedPatternForRoute(
+        route
+      );
+      tripPatterns.addAll(realTimeAddedPatternForRoute);
     }
-    return this.transitModelIndex.getPatternsForRoute().get(route);
+    return tripPatterns;
   }
 
   @Override
diff --git a/src/main/java/org/opentripplanner/transit/service/TransitService.java b/src/main/java/org/opentripplanner/transit/service/TransitService.java
index eca7a0fce5a..1836b5612d2 100644
--- a/src/main/java/org/opentripplanner/transit/service/TransitService.java
+++ b/src/main/java/org/opentripplanner/transit/service/TransitService.java
@@ -74,6 +74,9 @@ public interface TransitService {
 
   Collection<Notice> getNoticesByEntity(AbstractTransitEntity<?, ?> entity);
 
+  /**
+   * Return a trip pattern by id, not including patterns created by real-time updates.
+   */
   TripPattern getTripPatternForId(FeedScopedId id);
 
   /**
@@ -97,8 +100,15 @@ public interface TransitService {
 
   Agency getAgencyForId(FeedScopedId id);
 
+  /**
+   * Return a route for a given id, including routes created by real-time updates.
+   *
+   */
   Route getRouteForId(FeedScopedId id);
 
+  /**
+   * Return the routes using the given stop, not including real-time updates.
+   */
   Set<Route> getRoutesForStop(StopLocation stop);
 
   /**
@@ -149,22 +159,31 @@ public interface TransitService {
   @Nullable
   Trip getScheduledTripForId(FeedScopedId id);
 
+  /**
+   * Return all trips, including those created by real-time updates.
+   */
   Collection<Trip> getAllTrips();
 
+  /**
+   * Return all routes, including those created by real-time updates.
+   */
   Collection<Route> getAllRoutes();
 
   /**
-   * Return the scheduled trip pattern for a given trip (not taking into account real-time updates)
+   * Return the scheduled trip pattern for a given trip.
+   * If the trip is an added trip (extra journey), return the initial trip pattern for this trip.
    */
   TripPattern getPatternForTrip(Trip trip);
 
   /**
    * Return the trip pattern for a given trip on a service date. The real-time updated version
    * is returned if it exists, otherwise the scheduled trip pattern is returned.
-   *
    */
   TripPattern getPatternForTrip(Trip trip, LocalDate serviceDate);
 
+  /**
+   * Return all the trip patterns used in the given route, including those added by real-time updates
+   */
   Collection<TripPattern> getPatternsForRoute(Route route);
 
   MultiModalStation getMultiModalStationForStation(Station station);
@@ -208,12 +227,24 @@ List<TripTimeOnDate> stopTimesForPatternAtStop(
   @Nullable
   Timetable getTimetableForTripPattern(TripPattern tripPattern, LocalDate serviceDate);
 
+  /**
+   * Return the real-time added pattern for a given tripId and a given service date.
+   * Return null if the trip does not exist or if the trip has no real-time added pattern for
+   * this date (that is: it is still using its scheduled trip pattern for this date).
+   */
+  @Nullable
   TripPattern getRealtimeAddedTripPattern(FeedScopedId tripId, LocalDate serviceDate);
 
+  /**
+   * Return true if at least one trip pattern has been created by a real-time update.
+   */
   boolean hasRealtimeAddedTripPatterns();
 
   TripOnServiceDate getTripOnServiceDateForTripAndDay(TripIdAndServiceDate tripIdAndServiceDate);
 
+  /**
+   * Return the TripOnServiceDate for a given id, including real-time updates.
+   */
   TripOnServiceDate getTripOnServiceDateById(FeedScopedId datedServiceJourneyId);
 
   Collection<TripOnServiceDate> getAllTripOnServiceDates();