diff --git a/cartographer/sensor/collator.h b/cartographer/sensor/collator.h
index 54ffdea..b258aed 100644
--- a/cartographer/sensor/collator.h
+++ b/cartographer/sensor/collator.h
@@ -79,16 +79,6 @@ class Collator {
     queue_.Flush();
   }
 
-  // Returns the number of packets associated with 'trajectory_id' that are
-  // available for processing.
-  int num_available_packets(const int trajectory_id) {
-    int num = std::numeric_limits<int>::max();
-    for (const auto& queue_key : queue_keys_[trajectory_id]) {
-      num = std::min(num, queue_.num_available(queue_key));
-    }
-    return num;
-  }
-
  private:
   // Queue keys are a pair of trajectory ID and sensor identifier.
   OrderedMultiQueue queue_;
diff --git a/cartographer/sensor/ordered_multi_queue.h b/cartographer/sensor/ordered_multi_queue.h
index 321c84b..80a501a 100644
--- a/cartographer/sensor/ordered_multi_queue.h
+++ b/cartographer/sensor/ordered_multi_queue.h
@@ -105,11 +105,6 @@ class OrderedMultiQueue {
     }
   }
 
-  // Returns the number of available values associated with 'queue_key'.
-  int num_available(const QueueKey& queue_key) {
-    return FindOrDie(queue_key).queue.Size();
-  }
-
  private:
   struct Queue {
     common::BlockingQueue<std::unique_ptr<Data>> queue;