diff --git a/src/main/kotlin/eu/fosil/okupamicoche/entities/Travel.kt b/src/main/kotlin/eu/fosil/okupamicoche/entities/Travel.kt
index ef998fc..f72e73c 100644
--- a/src/main/kotlin/eu/fosil/okupamicoche/entities/Travel.kt
+++ b/src/main/kotlin/eu/fosil/okupamicoche/entities/Travel.kt
@@ -8,7 +8,7 @@ class Travel(
     @OneToOne
     var driver: User,
     @OneToMany
-    var travelers: List<User>,
+    var travelers: MutableList<User>,
     var departureDate: String,
     var origin: String,
     var destination: String,
diff --git a/src/main/kotlin/eu/fosil/okupamicoche/usecases/travel/AddTraveler.kt b/src/main/kotlin/eu/fosil/okupamicoche/usecases/travel/AddTraveler.kt
new file mode 100644
index 0000000..953092d
--- /dev/null
+++ b/src/main/kotlin/eu/fosil/okupamicoche/usecases/travel/AddTraveler.kt
@@ -0,0 +1,13 @@
+package eu.fosil.okupamicoche.usecases.travel
+
+import eu.fosil.okupamicoche.entities.Travel
+import eu.fosil.okupamicoche.entities.User
+import eu.fosil.okupamicoche.repositories.TravelRepository
+
+class AddTraveler(private val travelRepository: TravelRepository) {
+    fun addTraveler(travel: Travel, user: User) {
+        if (travel.travelers.none { u -> u.id == user.id })
+            travel.travelers.add(user)
+        travelRepository.save(travel)
+    }
+}
\ No newline at end of file
diff --git a/src/main/kotlin/eu/fosil/okupamicoche/usecases/travel/RemoveTraveler.kt b/src/main/kotlin/eu/fosil/okupamicoche/usecases/travel/RemoveTraveler.kt
new file mode 100644
index 0000000..2d8a0e2
--- /dev/null
+++ b/src/main/kotlin/eu/fosil/okupamicoche/usecases/travel/RemoveTraveler.kt
@@ -0,0 +1,12 @@
+package eu.fosil.okupamicoche.usecases.travel
+
+import eu.fosil.okupamicoche.entities.Travel
+import eu.fosil.okupamicoche.entities.User
+import eu.fosil.okupamicoche.repositories.TravelRepository
+
+class RemoveTraveler(private val travelRepository: TravelRepository) {
+    fun removeTraveler(travel: Travel, user: User) {
+        travel.travelers.remove(user)
+        travelRepository.save(travel)
+    }
+}
\ No newline at end of file