diff --git a/src/main/java/org/opentripplanner/netex/NetexModule.java b/src/main/java/org/opentripplanner/netex/NetexModule.java
index 1d946b33ad5..92ee25dbab2 100644
--- a/src/main/java/org/opentripplanner/netex/NetexModule.java
+++ b/src/main/java/org/opentripplanner/netex/NetexModule.java
@@ -90,7 +90,7 @@ public void buildGraph() {
         // TODO OTP2 - Move this into the AddTransitModelEntitiesToGraph
         //           - and make sure they also work with GTFS feeds - GTFS do no
         //           - have operators and notice assignments.
-        transitModel.getOperators().addAll(otpService.getAllOperators());
+        transitModel.addOperators(otpService.getAllOperators());
         transitModel.addNoticeAssignments(otpService.getNoticeAssignments());
 
         AddTransitModelEntitiesToGraph.addToGraph(
diff --git a/src/main/java/org/opentripplanner/transit/service/DefaultTransitService.java b/src/main/java/org/opentripplanner/transit/service/DefaultTransitService.java
index ad5c6586fe0..ce2d3aa0ad2 100644
--- a/src/main/java/org/opentripplanner/transit/service/DefaultTransitService.java
+++ b/src/main/java/org/opentripplanner/transit/service/DefaultTransitService.java
@@ -122,11 +122,6 @@ public void addFeedInfo(FeedInfo info) {
     this.transitModel.addFeedInfo(info);
   }
 
-  @Override
-  public Collection<Operator> getOperators() {
-    return this.transitModel.getOperators();
-  }
-
   @Override
   public Collection<Notice> getNoticesByEntity(AbstractTransitEntity<?, ?> entity) {
     return this.transitModel.getNoticesByElement().get(entity);
diff --git a/src/main/java/org/opentripplanner/transit/service/TransitModel.java b/src/main/java/org/opentripplanner/transit/service/TransitModel.java
index c22c69b6b0d..91c5ba8e5d9 100644
--- a/src/main/java/org/opentripplanner/transit/service/TransitModel.java
+++ b/src/main/java/org/opentripplanner/transit/service/TransitModel.java
@@ -350,7 +350,11 @@ public Set<ZoneId> getAgencyTimeZones() {
   }
 
   public Collection<Operator> getOperators() {
-    return operators;
+    return Collections.unmodifiableCollection(operators);
+  }
+
+  public void addOperators(Collection<Operator> operators) {
+    this.operators.addAll(operators);
   }
 
   /**
diff --git a/src/main/java/org/opentripplanner/transit/service/TransitService.java b/src/main/java/org/opentripplanner/transit/service/TransitService.java
index 406d0cebc67..12fcbc9bc46 100644
--- a/src/main/java/org/opentripplanner/transit/service/TransitService.java
+++ b/src/main/java/org/opentripplanner/transit/service/TransitService.java
@@ -71,8 +71,6 @@ public interface TransitService {
 
   FeedInfo getFeedInfo(String feedId);
 
-  Collection<Operator> getOperators();
-
   Collection<Notice> getNoticesByEntity(AbstractTransitEntity<?, ?> entity);
 
   /**
diff --git a/src/test/java/org/opentripplanner/updater/trip/RealtimeTestEnvironmentBuilder.java b/src/test/java/org/opentripplanner/updater/trip/RealtimeTestEnvironmentBuilder.java
index aab71628b03..3203d7d49fc 100644
--- a/src/test/java/org/opentripplanner/updater/trip/RealtimeTestEnvironmentBuilder.java
+++ b/src/test/java/org/opentripplanner/updater/trip/RealtimeTestEnvironmentBuilder.java
@@ -68,7 +68,7 @@ private Trip createTrip(TripInput tripInput) {
     transitModel.addTripOnServiceDate(tripOnServiceDate);
 
     if (tripInput.route().getOperator() != null) {
-      transitModel.getOperators().add(tripInput.route().getOperator());
+      transitModel.addOperators(List.of(tripInput.route().getOperator()));
     }
 
     var stopTimes = IntStream