diff --git a/src/main/java/org/matsim/prepare/population/AssignReferencePopulation.java b/src/main/java/org/matsim/prepare/population/AssignReferencePopulation.java
index a468698d..cc0b6fff 100644
--- a/src/main/java/org/matsim/prepare/population/AssignReferencePopulation.java
+++ b/src/main/java/org/matsim/prepare/population/AssignReferencePopulation.java
@@ -11,6 +11,7 @@
 import org.matsim.api.core.v01.population.Plan;
 import org.matsim.api.core.v01.population.Population;
 import org.matsim.application.MATSimAppCommand;
+import org.matsim.application.analysis.population.TripAnalysis;
 import org.matsim.application.options.ShpOptions;
 import org.matsim.core.population.PopulationUtils;
 import org.matsim.core.router.TripStructureUtils;
@@ -131,13 +132,14 @@ public Integer call() throws Exception {
 
 				if (success) {
 					sampling.copyAttributes(p, person);
-					person.getAttributes().putAttribute(Attributes.REF_WEIGHT, p.get("p_weight"));
+					person.getAttributes().putAttribute(TripAnalysis.ATTR_REF_WEIGHT, p.get("p_weight"));
 					person.removePlan(person.getSelectedPlan());
 					person.addPlan(plan);
 					person.setSelectedPlan(plan);
 
 					String refModes = TripStructureUtils.getLegs(plan).stream().map(Leg::getMode).collect(Collectors.joining("-"));
-					person.getAttributes().putAttribute(Attributes.REF_MODES, refModes);
+					person.getAttributes().putAttribute(TripAnalysis.ATTR_REF_MODES, refModes);
+					person.getAttributes().putAttribute(TripAnalysis.ATTR_REF_ID, e.getKey());
 
 					// remove person that have been used as reference
 					refPersons.remove(person);
diff --git a/src/main/java/org/matsim/prepare/population/Attributes.java b/src/main/java/org/matsim/prepare/population/Attributes.java
index b2d6bb8e..bbeaf3a9 100644
--- a/src/main/java/org/matsim/prepare/population/Attributes.java
+++ b/src/main/java/org/matsim/prepare/population/Attributes.java
@@ -4,6 +4,7 @@
 import org.matsim.api.core.v01.Id;
 import org.matsim.api.core.v01.network.Link;
 import org.matsim.api.core.v01.population.Person;
+import org.matsim.application.analysis.population.TripAnalysis;
 
 import java.util.Objects;
 
@@ -36,8 +37,7 @@ public final class Attributes {
 	public static final String RESTRICTED_MOBILITY = "restricted_mobility";
 	public static final String ECONOMIC_STATUS = "economic_status";
 	public static final String HOUSEHOLD_SIZE = "household_size";
-	public static final String REF_WEIGHT = "ref_weight";
-	public static final String REF_MODES = "ref_modes";
+	public static final String REF_MODES = TripAnalysis.ATTR_REF_MODES;
 	public static final String ATTRACTION_WORK = "attraction_work";
 	public static final String ATTRACTION_OTHER = "attraction_other";
 
diff --git a/src/main/java/org/matsim/prepare/population/PlanBuilder.java b/src/main/java/org/matsim/prepare/population/PlanBuilder.java
index 5265750e..b4cb0b17 100644
--- a/src/main/java/org/matsim/prepare/population/PlanBuilder.java
+++ b/src/main/java/org/matsim/prepare/population/PlanBuilder.java
@@ -39,11 +39,6 @@ public class PlanBuilder {
 	private static final Logger log = LogManager.getLogger(PlanBuilder.class);
 	private static final CsvOptions csv = new CsvOptions(CSVFormat.Predefined.Default);
 
-	/**
-	 * Stores of warning for a zone was generated.
-	 */
-	private final Set<Location> warnings = new HashSet<>();
-
 	/**
 	 * Maps zone ids to contained facilities.
 	 */
@@ -60,10 +55,6 @@ public class PlanBuilder {
 
 	private final SplittableRandom rnd = new SplittableRandom();
 
-	/**
-	 * Drop plans with more than this number of trips.
-	 */
-	private int maxTripNumber = 0;
 
 	public PlanBuilder(ShpOptions zones, FacilityIndex facilities, Path activityPath) throws IOException {
 		// Collect all zones
@@ -86,24 +77,6 @@ public PlanBuilder(ShpOptions zones, FacilityIndex facilities, Path activityPath
 		}
 	}
 
-	/**
-	 * Add necesarry vehicles to the scenario.
-	 */
-	public static void addVehiclesToScenario(Scenario scenario) {
-		Id<Vehicle> car = Id.createVehicleId("car");
-		Vehicle vehicle = scenario.getVehicles().getFactory().createVehicle(
-			car, scenario.getVehicles().getVehicleTypes().get(Id.create("car", VehicleType.class))
-		);
-		scenario.getVehicles().addVehicle(vehicle);
-
-		Id<Vehicle> ride = Id.createVehicleId("ride");
-		vehicle = scenario.getVehicles().getFactory().createVehicle(
-			ride, scenario.getVehicles().getVehicleTypes().get(Id.create("ride", VehicleType.class))
-		);
-		scenario.getVehicles().addVehicle(vehicle);
-
-	}
-
 	private void readActivities(CSVParser csv, String idColumn) {
 
 		String currentId = null;