diff --git a/ClumsyPilot/ParkrobTrajplanner/EMPlanner/Longitudinal/LongitudinalConstraintBuilder.cs b/ClumsyPilot/ParkrobTrajplanner/EMPlanner/Longitudinal/LongitudinalConstraintBuilder.cs
index 040fc17..49c5a5c 100644
--- a/ClumsyPilot/ParkrobTrajplanner/EMPlanner/Longitudinal/LongitudinalConstraintBuilder.cs
+++ b/ClumsyPilot/ParkrobTrajplanner/EMPlanner/Longitudinal/LongitudinalConstraintBuilder.cs
@@ -40,7 +40,7 @@ public sealed class LongitudinalConstraintBuilder
             {
                 return false;
             }
-            if (input.InitialProgressSpeedMetersPerSecond > speedLimit.MaximumSpeedAt(0d) + 1e-12d ||
+            if (input.InitialProgressSpeedMetersPerSecond > directionMaximum + 1e-12d ||
                 input.InitialAccelerationMetersPerSecondSquared < -maximumDeceleration - 1e-12d ||
                 input.InitialAccelerationMetersPerSecondSquared > maximumAcceleration + 1e-12d)
             {
@@ -90,8 +90,10 @@ public sealed class LongitudinalConstraintBuilder
             if (iterate.S[index] < 0d || iterate.S[index] > input.PathUpperBoundS)
                 throw new ArgumentException("The ST iterate progress lies outside actual PathS bounds.");
             AddSingleVariableRow(constraints, lower, upper, layout.S(index), 0d, input.PathUpperBoundS, ref row);
-            AddSingleVariableRow(constraints, lower, upper, layout.U(index), 0d,
-                Math.Min(input.DirectionMaximumSpeedMetersPerSecond, speedLimit.MaximumSpeedAt(iterate.S[index])), ref row);
+            double maximumSpeed = index == 0
+                ? input.DirectionMaximumSpeedMetersPerSecond
+                : Math.Min(input.DirectionMaximumSpeedMetersPerSecond, speedLimit.MaximumSpeedAt(iterate.S[index]));
+            AddSingleVariableRow(constraints, lower, upper, layout.U(index), 0d, maximumSpeed, ref row);
             AddSingleVariableRow(constraints, lower, upper, layout.A(index), -maximumDeceleration, maximumAcceleration,
                 ref row);
         }
diff --git a/ClumsyPilot/ParkrobTrajplanner/EMPlanner/Longitudinal/LongitudinalSolutionValidator.cs b/ClumsyPilot/ParkrobTrajplanner/EMPlanner/Longitudinal/LongitudinalSolutionValidator.cs
index c365e57..3ff71c1 100644
--- a/ClumsyPilot/ParkrobTrajplanner/EMPlanner/Longitudinal/LongitudinalSolutionValidator.cs
+++ b/ClumsyPilot/ParkrobTrajplanner/EMPlanner/Longitudinal/LongitudinalSolutionValidator.cs
@@ -62,8 +62,9 @@ public sealed class LongitudinalSolutionValidator
                     failureReason = "ST candidate violates physical bounds at knot " + index + ".";
                     return false;
                 }
-                double speedLimitAtProgress = speedLimit.MaximumSpeedAt(
-                    Math.Max(0d, Math.Min(input.PathUpperBoundS, progress)));
+                double speedLimitAtProgress = index == 0
+                    ? input.DirectionMaximumSpeedMetersPerSecond
+                    : speedLimit.MaximumSpeedAt(Math.Max(0d, Math.Min(input.PathUpperBoundS, progress)));
                 if (speed > speedLimitAtProgress + tolerance)
                 {
                     failureReason = "ST candidate violates the actual-PathS speed envelope at knot " + index +