diff --git a/include/engine/guidance/assemble_steps.hpp b/include/engine/guidance/assemble_steps.hpp
index 2bef099ad..0f52995d3 100644
--- a/include/engine/guidance/assemble_steps.hpp
+++ b/include/engine/guidance/assemble_steps.hpp
@@ -209,13 +209,22 @@ inline std::vector<RouteStep> assembleSteps(const datafacade::BaseDataFacade &fa
     else
     {
         BOOST_ASSERT(source_node.fwd_segment_position == target_node.fwd_segment_position);
-        //     s     t
-        // u-------------v
-        // |---| source_duration
-        // |---------| target_duration
+        BOOST_ASSERT(source_traversed_in_reverse == target_traversed_in_reverse);
 
-        const EdgeWeight duration = target_duration - source_duration;
+        // The difference (target-source) should handle
+        // all variants for similar directions u-v and s-t (and opposite)
+        //    s(t)  t(s)   source_traversed_in_reverse = target_traversed_in_reverse = false
+        // u-------------v
+        // |---|           source_weight
+        // |---------|     target_weight
+
+        //    s(t)  t(s)   source_traversed_in_reverse = target_traversed_in_reverse = true
+        // u-------------v
+        // |   |---------| source_weight
+        // |         |---| target_weight
         const EdgeWeight weight = target_weight - source_weight;
+        const EdgeWeight duration = target_duration - source_duration;
+        BOOST_ASSERT(weight >= 0);
         BOOST_ASSERT(duration >= 0);
 
         steps.push_back(RouteStep{source_node.name_id,
diff --git a/include/engine/routing_algorithms/routing_base_mld.hpp b/include/engine/routing_algorithms/routing_base_mld.hpp
index 47788f5b3..2af6ab747 100644
--- a/include/engine/routing_algorithms/routing_base_mld.hpp
+++ b/include/engine/routing_algorithms/routing_base_mld.hpp
@@ -35,12 +35,16 @@ void routingStep(const datafacade::ContiguousInternalMemoryDataFacade<algorithm:
     const auto weight = forward_heap.GetKey(node);
 
     auto update_upper_bounds = [&](NodeID to, EdgeWeight forward_weight, EdgeWeight edge_weight) {
-        if (reverse_heap.WasInserted(to) && reverse_heap.WasRemoved(to))
+        // Upper bound for the path source -> target with
+        // weight(source -> node) = forward_weight, weight(node -> to) = edge_weight and
+        // weight(to -> target) ≤ reverse_weight is forward_weight + edge_weight + reverse_weight
+        // More tighter upper bound requires additional condition reverse_heap.WasRemoved(to)
+        // with weight(to -> target) = reverse_weight and all weights ≥ 0
+        if (reverse_heap.WasInserted(to))
         {
             auto reverse_weight = reverse_heap.GetKey(to);
             auto path_weight = forward_weight + edge_weight + reverse_weight;
-            BOOST_ASSERT(path_weight >= 0);
-            if (path_weight < path_upper_bound)
+            if (path_weight >= 0 && path_weight < path_upper_bound)
             {
                 middle_node = to;
                 path_upper_bound = path_weight;