Index: train_cmd.c
===================================================================
--- train_cmd.c	(revision 11224)
+++ train_cmd.c	(working copy)
@@ -614,7 +614,8 @@
 
 			FOR_ALL_VEHICLES(w) {
 				if (w->type == VEH_Train && w->tile == tile &&
-				    IsFreeWagon(w) && w->engine_type == engine) {
+				    IsFreeWagon(w) && w->engine_type == engine &&
+				    !HASBITS(w->vehstatus, VS_CRASHED)) {          /// do not connect new wagon with crashed/flooded consists
 					u = GetLastVehicleInChain(w);
 					break;
 				}
@@ -935,7 +936,7 @@
 	TileIndex tile = src->tile;
 
 	FOR_ALL_VEHICLES(dst) {
-		if (dst->type == VEH_Train && IsFreeWagon(dst) && dst->tile == tile) {
+		if (dst->type == VEH_Train && IsFreeWagon(dst) && dst->tile == tile && !HASBITS(dst->vehstatus, VS_CRASHED)) {
 			// check so all vehicles in the line have the same engine.
 			Vehicle *v = dst;
 
@@ -1006,6 +1007,9 @@
 
 	if (src->type != VEH_Train || !CheckOwnership(src->owner)) return CMD_ERROR;
 
+	/* Do not allow moving crashed vehicles inside the depot, it is likely to cause asserts later */
+	if (HASBITS(src->vehstatus, VS_CRASHED)) return CMD_ERROR;
+
 	// if nothing is selected as destination, try and find a matching vehicle to drag to.
 	if (d == INVALID_VEHICLE) {
 		dst = IsTrainEngine(src) ? NULL : FindGoodVehiclePos(src);
@@ -1013,6 +1017,9 @@
 		if (!IsValidVehicleID(d)) return CMD_ERROR;
 		dst = GetVehicle(d);
 		if (dst->type != VEH_Train || !CheckOwnership(dst->owner)) return CMD_ERROR;
+
+		/* Do not allow appending to crashed vehicles, too */
+		if (HASBITS(dst->vehstatus, VS_CRASHED)) return CMD_ERROR;
 	}
 
 	// if an articulated part is being handled, deal with its parent vehicle
@@ -3579,9 +3586,15 @@
 		if (v->type == VEH_Train && IsFrontEngine(v))
 			TrainLocoHandler(v, true);
 	} else if (IsFreeWagon(v) && HASBITS(v->vehstatus, VS_CRASHED)) {
-		// Delete flooded standalone wagon
-		if (++v->u.rail.crash_anim_pos >= 4400)
-			DeleteVehicle(v);
+		// Delete flooded standalone wagon chain
+		if (++v->u.rail.crash_anim_pos >= 4400) {
+			Vehicle *w = GetFirstVehicleInChain(v);
+			do {
+				Vehicle *u = w->next;
+				DeleteVehicle(w);
+				w = u;
+			} while (w != NULL);
+		}
 	}
 }