diff --git a/contribs/drt/src/main/java/org/matsim/contrib/drt/optimizer/constraints/ConstraintSetChooser.java b/contribs/drt/src/main/java/org/matsim/contrib/drt/optimizer/constraints/ConstraintSetChooser.java
index 2be22eeb9d8..124da1a39bb 100644
--- a/contribs/drt/src/main/java/org/matsim/contrib/drt/optimizer/constraints/ConstraintSetChooser.java
+++ b/contribs/drt/src/main/java/org/matsim/contrib/drt/optimizer/constraints/ConstraintSetChooser.java
@@ -4,11 +4,13 @@
 import org.matsim.api.core.v01.population.Person;
 import org.matsim.utils.objectattributes.attributable.Attributes;
 
+import java.util.Optional;
+
 /**
  * @author nkuehnel / MOIA
  */
 public interface ConstraintSetChooser {
 
-    DrtOptimizationConstraintsSet chooseConstraintSet(double departureTime, Link accessActLink, Link egressActLink, Person person,
-                                                      Attributes tripAttributes);
+    Optional<DrtOptimizationConstraintsSet> chooseConstraintSet(double departureTime, Link accessActLink,
+                                                                Link egressActLink, Person person, Attributes tripAttributes);
 }
diff --git a/contribs/drt/src/main/java/org/matsim/contrib/drt/routing/DrtRouteCreator.java b/contribs/drt/src/main/java/org/matsim/contrib/drt/routing/DrtRouteCreator.java
index f002460fbaa..45dce290b0f 100644
--- a/contribs/drt/src/main/java/org/matsim/contrib/drt/routing/DrtRouteCreator.java
+++ b/contribs/drt/src/main/java/org/matsim/contrib/drt/routing/DrtRouteCreator.java
@@ -24,7 +24,6 @@
 import org.matsim.api.core.v01.population.Person;
 import org.matsim.api.core.v01.population.Route;
 import org.matsim.contrib.drt.optimizer.constraints.ConstraintSetChooser;
-import org.matsim.contrib.drt.optimizer.constraints.DefaultDrtOptimizationConstraintsSet;
 import org.matsim.contrib.drt.optimizer.constraints.DrtOptimizationConstraintsSet;
 import org.matsim.contrib.drt.run.DrtConfigGroup;
 import org.matsim.contrib.dvrp.path.VrpPathWithTravelData;
@@ -72,7 +71,9 @@ public Route createRoute(double departureTime, Link accessActLink, Link egressAc
 		double unsharedRideTime = unsharedPath.getTravelTime();//includes first & last link
 		double unsharedDistance = VrpPaths.calcDistance(unsharedPath);//includes last link
 
-		DrtOptimizationConstraintsSet constraintsSet = constraintSetChooser.chooseConstraintSet(departureTime, accessActLink, egressActLink, person, tripAttributes);
+		DrtOptimizationConstraintsSet constraintsSet =
+				constraintSetChooser.chooseConstraintSet(departureTime, accessActLink, egressActLink, person, tripAttributes)
+						.orElse(drtCfg.addOrGetDrtOptimizationConstraintsParams().addOrGetDefaultDrtOptimizationConstraintsSet());
 		double maxTravelTime = routeConstraintsCalculator.getMaxTravelTime(constraintsSet, unsharedRideTime);
 		double maxRideDuration = routeConstraintsCalculator.getMaxRideTime(constraintsSet, unsharedRideTime);
 
diff --git a/contribs/drt/src/main/java/org/matsim/contrib/drt/run/DrtModeRoutingModule.java b/contribs/drt/src/main/java/org/matsim/contrib/drt/run/DrtModeRoutingModule.java
index 7643ed97dab..d0b82a10f10 100644
--- a/contribs/drt/src/main/java/org/matsim/contrib/drt/run/DrtModeRoutingModule.java
+++ b/contribs/drt/src/main/java/org/matsim/contrib/drt/run/DrtModeRoutingModule.java
@@ -58,6 +58,7 @@
 
 import java.net.URL;
 import java.util.List;
+import java.util.Optional;
 
 /**
  * This is a DRT-customised version of DvrpModeRoutingModule
@@ -100,7 +101,7 @@ public void install() {
 		DefaultDrtOptimizationConstraintsSet optimizationConstraintsSet = drtCfg.addOrGetDrtOptimizationConstraintsParams().addOrGetDefaultDrtOptimizationConstraintsSet();
 		bindModal(ConstraintSetChooser.class).toProvider(
 				() -> (departureTime, accessActLink, egressActLink, person, tripAttributes)
-						-> optimizationConstraintsSet
+						-> Optional.of(optimizationConstraintsSet)
 		).in(Singleton.class);
 
 		switch( drtCfg.operationalScheme ){
diff --git a/contribs/drt/src/test/java/org/matsim/contrib/drt/config/ConfigBehaviorTest.java b/contribs/drt/src/test/java/org/matsim/contrib/drt/config/ConfigBehaviorTest.java
index 2e920f3cf62..0c365bbc5e7 100644
--- a/contribs/drt/src/test/java/org/matsim/contrib/drt/config/ConfigBehaviorTest.java
+++ b/contribs/drt/src/test/java/org/matsim/contrib/drt/config/ConfigBehaviorTest.java
@@ -121,7 +121,7 @@ final void testMaterializeAfterReadDrtConstraints() {
     }
 
     @Test
-    final void testMaterializeAfterReadStandardParams3() {
+    final void testMaterializeAfterReadCustomDrtConstraints() {
         {
             // generate a test config that sets two values away from their defaults, and write it to file:
             Config config = ConfigUtils.createConfig();
@@ -142,13 +142,13 @@ final void testMaterializeAfterReadStandardParams3() {
 
         {
             // load config file without materializing the drt config group
-            MultiModeDrtConfigGroup multiModeDrtConfigGroup1 =
+            MultiModeDrtConfigGroup multiModeDrtConfigGroup =
                     new MultiModeDrtConfigGroup(() -> new DrtConfigGroup(CustomConstraintsSet::new));
 
-            Config config = ConfigUtils.loadConfig( new String[] { utils.getOutputDirectory() + "ad-hoc-config-custom-optimization-constraints.xml"}, multiModeDrtConfigGroup1);
+            Config config = ConfigUtils.loadConfig( new String[] { utils.getOutputDirectory() + "ad-hoc-config-custom-optimization-constraints.xml"}, multiModeDrtConfigGroup);
 
             // materialize the config group
-            MultiModeDrtConfigGroup multiModeDrtConfigGroup = ConfigUtils.addOrGetModule( config, MultiModeDrtConfigGroup.class );
+            //MultiModeDrtConfigGroup multiModeDrtConfigGroup = ConfigUtils.addOrGetModule( config, MultiModeDrtConfigGroup.class );
             DrtConfigGroup drtConfigGroup = multiModeDrtConfigGroup.getModalElements().iterator().next();
 
             // check if you are getting back the values from the config file:
diff --git a/contribs/drt/src/test/java/org/matsim/contrib/drt/routing/DrtRoutingModuleTest.java b/contribs/drt/src/test/java/org/matsim/contrib/drt/routing/DrtRoutingModuleTest.java
index be99a55d320..8325834c96b 100644
--- a/contribs/drt/src/test/java/org/matsim/contrib/drt/routing/DrtRoutingModuleTest.java
+++ b/contribs/drt/src/test/java/org/matsim/contrib/drt/routing/DrtRoutingModuleTest.java
@@ -19,9 +19,7 @@
 
 package org.matsim.contrib.drt.routing;
 
-import java.util.Arrays;
-import java.util.List;
-
+import com.google.common.collect.ImmutableMap;
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.extension.RegisterExtension;
@@ -30,15 +28,8 @@
 import org.matsim.api.core.v01.Scenario;
 import org.matsim.api.core.v01.TransportMode;
 import org.matsim.api.core.v01.network.Link;
-import org.matsim.api.core.v01.population.Activity;
-import org.matsim.api.core.v01.population.Leg;
-import org.matsim.api.core.v01.population.Person;
-import org.matsim.api.core.v01.population.Plan;
-import org.matsim.api.core.v01.population.PlanElement;
-import org.matsim.api.core.v01.population.PopulationFactory;
-import org.matsim.contrib.drt.optimizer.constraints.ConstraintSetChooser;
+import org.matsim.api.core.v01.population.*;
 import org.matsim.contrib.drt.optimizer.constraints.DefaultDrtOptimizationConstraintsSet;
-import org.matsim.contrib.drt.optimizer.constraints.DrtOptimizationConstraintsSet;
 import org.matsim.contrib.drt.run.DrtConfigGroup;
 import org.matsim.contrib.drt.run.DrtControlerCreator;
 import org.matsim.contrib.drt.run.MultiModeDrtConfigGroup;
@@ -63,8 +54,9 @@
 import org.matsim.pt.transitSchedule.api.TransitScheduleReader;
 import org.matsim.testcases.MatsimTestUtils;
 
-import com.google.common.collect.ImmutableMap;
-import org.matsim.utils.objectattributes.attributable.Attributes;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Optional;
 
 /**
  * @author jbischoff
@@ -102,7 +94,7 @@ void testCottbusClosestAccessEgressStopFinder() {
 		DrtRouteCreator drtRouteCreator = new DrtRouteCreator(drtCfg, scenario.getNetwork(),
 				new SpeedyDijkstraFactory(), new FreeSpeedTravelTime(), TimeAsTravelDisutility::new,
 				new DefaultDrtRouteConstraintsCalculator(),
-				(departureTime, accessActLink, egressActLink, person, tripAttributes) -> defaultConstraintsSet);
+				(departureTime, accessActLink, egressActLink, person, tripAttributes) -> Optional.of(defaultConstraintsSet));
 		DefaultMainLegRouter mainRouter = new DefaultMainLegRouter(drtMode, scenario.getNetwork(),
 				scenario.getPopulation().getFactory(), drtRouteCreator);
 		DvrpRoutingModule dvrpRoutingModule = new DvrpRoutingModule(mainRouter, walkRouter, walkRouter, stopFinder,