diff --git a/osi_lane.proto b/osi_lane.proto
index 91bd68cc3..5d2e1e508 100644
--- a/osi_lane.proto
+++ b/osi_lane.proto
@@ -631,6 +631,18 @@ message LaneBoundary
         // See \c LaneBoundary .
         //
         optional double height = 3;
+
+        // The rotation about the longitudinal axis of the lane boundary
+        // at the position of the \c BoundaryPoint .
+        // Necessary for boundary points with a specified height and/or
+        // width parameter.
+        //
+        // Unit: rad
+        //
+        // \note Field need not be set if it is previously defined.
+        // See \c LaneBoundary .
+        //
+        optional double roll = 4;
     }
 
     //