diff --git a/src/main/java/at/ac/ait/matsim/drs/optimizer/DrsRequest.java b/src/main/java/at/ac/ait/matsim/drs/optimizer/DrsRequest.java
index 2d01ff3..cfb2ea3 100644
--- a/src/main/java/at/ac/ait/matsim/drs/optimizer/DrsRequest.java
+++ b/src/main/java/at/ac/ait/matsim/drs/optimizer/DrsRequest.java
@@ -45,6 +45,7 @@ public abstract class DrsRequest implements Request {
      * leg or a drs leg accompanied by walk access and egress legs.
      *
      * @param drsNetwork must only consist of links accessible to the drsDriver mode
+     * @return null in case no useful request can be created
      */
     public static DrsRequest create(Id<Request> id, RoutingModule driverRouter, Network drsNetwork, Person person,
             Trip trip) {
diff --git a/src/main/java/at/ac/ait/matsim/drs/optimizer/RequestsCollector.java b/src/main/java/at/ac/ait/matsim/drs/optimizer/RequestsCollector.java
index 6ee793e..49d4a32 100644
--- a/src/main/java/at/ac/ait/matsim/drs/optimizer/RequestsCollector.java
+++ b/src/main/java/at/ac/ait/matsim/drs/optimizer/RequestsCollector.java
@@ -63,6 +63,9 @@ public void collectRequests() {
 
                 Id<Request> id = Id.create(++requestId, Request.class);
                 DrsRequest request = DrsRequest.create(id, driverRouter, drsNetwork, person, trip);
+                if (request == null) {
+                    continue;
+                }
 
                 double distance = request.getNetworkRouteDistance();
                 if (request instanceof DrsDriverRequest) {