diff --git a/cartographer/mapping_2d/sparse_pose_graph.cc b/cartographer/mapping_2d/sparse_pose_graph.cc
index 32e5a23..e4440dd 100644
--- a/cartographer/mapping_2d/sparse_pose_graph.cc
+++ b/cartographer/mapping_2d/sparse_pose_graph.cc
@@ -127,7 +127,7 @@ void SparsePoseGraph::AddScan(
   }
 
   AddWorkItem([=]() REQUIRES(mutex_) {
-    ComputeConstraintsForScan(time, j, matching_submap, insertion_submaps,
+    ComputeConstraintsForScan(j, matching_submap, insertion_submaps,
                               finished_submap, pose, covariance);
   });
 }
@@ -199,8 +199,7 @@ void SparsePoseGraph::ComputeConstraintsForOldScans(
 }
 
 void SparsePoseGraph::ComputeConstraintsForScan(
-    const common::Time time, const int scan_index,
-    const mapping::Submap* matching_submap,
+    const int scan_index, const mapping::Submap* matching_submap,
     std::vector<const mapping::Submap*> insertion_submaps,
     const mapping::Submap* finished_submap, const transform::Rigid2d& pose,
     const kalman_filter::Pose2DCovariance& covariance) {
@@ -210,10 +209,10 @@ void SparsePoseGraph::ComputeConstraintsForScan(
       submap_transforms_[matching_index] *
       sparse_pose_graph::ComputeSubmapPose(*matching_submap).inverse() * pose;
   CHECK_EQ(scan_index, optimization_problem_.node_data().size());
-  const mapping::Submaps* const scan_trajectory =
-      trajectory_nodes_[scan_index].constant_data->trajectory;
-  optimization_problem_.AddTrajectoryNode(scan_trajectory, time, pose,
-                                          optimized_pose);
+  const mapping::TrajectoryNode::ConstantData* const scan_data =
+      trajectory_nodes_[scan_index].constant_data;
+  optimization_problem_.AddTrajectoryNode(
+      scan_data->trajectory, scan_data->time, pose, optimized_pose);
   for (const mapping::Submap* submap : insertion_submaps) {
     const int submap_index = GetSubmapIndex(submap);
     CHECK(!submap_states_[submap_index].finished);
diff --git a/cartographer/mapping_2d/sparse_pose_graph.h b/cartographer/mapping_2d/sparse_pose_graph.h
index 4e747eb..2136f38 100644
--- a/cartographer/mapping_2d/sparse_pose_graph.h
+++ b/cartographer/mapping_2d/sparse_pose_graph.h
@@ -132,7 +132,7 @@ class SparsePoseGraph : public mapping::SparsePoseGraph {
 
   // Adds constraints for a scan, and starts scan matching in the background.
   void ComputeConstraintsForScan(
-      common::Time time, int scan_index, const mapping::Submap* matching_submap,
+      int scan_index, const mapping::Submap* matching_submap,
       std::vector<const mapping::Submap*> insertion_submaps,
       const mapping::Submap* finished_submap, const transform::Rigid2d& pose,
       const kalman_filter::Pose2DCovariance& covariance) REQUIRES(mutex_);
diff --git a/cartographer/mapping_2d/sparse_pose_graph/optimization_problem.cc b/cartographer/mapping_2d/sparse_pose_graph/optimization_problem.cc
index 091a29a..3cfa996 100644
--- a/cartographer/mapping_2d/sparse_pose_graph/optimization_problem.cc
+++ b/cartographer/mapping_2d/sparse_pose_graph/optimization_problem.cc
@@ -107,24 +107,19 @@ void OptimizationProblem::Solve(
   problem.SetParameterBlockConstant(C_submaps[0].data());
 
   // Add cost functions for intra- and inter-submap constraints.
-  std::vector<std::pair<Constraint::Tag, ceres::ResidualBlockId>>
-      constraints_residual_blocks;
   for (const Constraint& constraint : constraints) {
     CHECK_GE(constraint.i, 0);
     CHECK_LT(constraint.i, submap_transforms->size());
     CHECK_GE(constraint.j, 0);
     CHECK_LT(constraint.j, node_data_.size());
-    constraints_residual_blocks.emplace_back(
-        constraint.tag,
-        problem.AddResidualBlock(
-            new ceres::AutoDiffCostFunction<SpaCostFunction, 3, 3, 3>(
-                new SpaCostFunction(constraint.pose)),
-            // Only loop closure constraints should have a loss function.
-            constraint.tag == Constraint::INTER_SUBMAP
-                ? new ceres::HuberLoss(options_.huber_scale())
-                : nullptr,
-            C_submaps[constraint.i].data(),
-            C_point_clouds[constraint.j].data()));
+    problem.AddResidualBlock(
+        new ceres::AutoDiffCostFunction<SpaCostFunction, 3, 3, 3>(
+            new SpaCostFunction(constraint.pose)),
+        // Only loop closure constraints should have a loss function.
+        constraint.tag == Constraint::INTER_SUBMAP
+            ? new ceres::HuberLoss(options_.huber_scale())
+            : nullptr,
+        C_submaps[constraint.i].data(), C_point_clouds[constraint.j].data());
   }
 
   // Add penalties for changes between consecutive scans.
diff --git a/cartographer/mapping_3d/sparse_pose_graph.cc b/cartographer/mapping_3d/sparse_pose_graph.cc
index 50f5a31..2f2cd19 100644
--- a/cartographer/mapping_3d/sparse_pose_graph.cc
+++ b/cartographer/mapping_3d/sparse_pose_graph.cc
@@ -123,7 +123,7 @@ int SparsePoseGraph::AddScan(
   }
 
   AddWorkItem([=]() REQUIRES(mutex_) {
-    ComputeConstraintsForScan(time, j, matching_submap, insertion_submaps,
+    ComputeConstraintsForScan(j, matching_submap, insertion_submaps,
                               finished_submap, pose, covariance);
   });
   return j;
@@ -194,9 +194,9 @@ void SparsePoseGraph::ComputeConstraintsForOldScans(const Submap* submap) {
 }
 
 void SparsePoseGraph::ComputeConstraintsForScan(
-    const common::Time time, const int scan_index,
-    const Submap* matching_submap, std::vector<const Submap*> insertion_submaps,
-    const Submap* finished_submap, const transform::Rigid3d& pose,
+    const int scan_index, const Submap* matching_submap,
+    std::vector<const Submap*> insertion_submaps, const Submap* finished_submap,
+    const transform::Rigid3d& pose,
     const kalman_filter::PoseCovariance& covariance) {
   GrowSubmapTransformsAsNeeded(insertion_submaps);
   const int matching_index = GetSubmapIndex(matching_submap);
@@ -204,10 +204,10 @@ void SparsePoseGraph::ComputeConstraintsForScan(
       submap_transforms_[matching_index] *
       matching_submap->local_pose().inverse() * pose;
   CHECK_EQ(scan_index, optimization_problem_.node_data().size());
-  const mapping::Submaps* const scan_trajectory =
-      trajectory_nodes_[scan_index].constant_data->trajectory;
-  optimization_problem_.AddTrajectoryNode(scan_trajectory, time,
-                                          optimized_pose);
+  const mapping::TrajectoryNode::ConstantData* const scan_data =
+      trajectory_nodes_[scan_index].constant_data;
+  optimization_problem_.AddTrajectoryNode(scan_data->trajectory,
+                                          scan_data->time, optimized_pose);
   for (const Submap* submap : insertion_submaps) {
     const int submap_index = GetSubmapIndex(submap);
     CHECK(!submap_states_[submap_index].finished);
diff --git a/cartographer/mapping_3d/sparse_pose_graph.h b/cartographer/mapping_3d/sparse_pose_graph.h
index 4c58c2b..4cd6b08 100644
--- a/cartographer/mapping_3d/sparse_pose_graph.h
+++ b/cartographer/mapping_3d/sparse_pose_graph.h
@@ -130,7 +130,7 @@ class SparsePoseGraph : public mapping::SparsePoseGraph {
 
   // Adds constraints for a scan, and starts scan matching in the background.
   void ComputeConstraintsForScan(
-      common::Time time, int scan_index, const Submap* matching_submap,
+      int scan_index, const Submap* matching_submap,
       std::vector<const Submap*> insertion_submaps,
       const Submap* finished_submap, const transform::Rigid3d& pose,
       const kalman_filter::PoseCovariance& covariance) REQUIRES(mutex_);