diff --git a/apps/ltn/src/filters/mod.rs b/apps/ltn/src/filters/mod.rs
index a04d59ee16..e8ec16d916 100644
--- a/apps/ltn/src/filters/mod.rs
+++ b/apps/ltn/src/filters/mod.rs
@@ -7,7 +7,7 @@ use serde::{Deserialize, Serialize};
 
 use abstutil::{deserialize_btreemap, serialize_btreemap};
 use geom::{Circle, Distance, Line};
-use map_model::{IntersectionID, Map, RoadID, RoutingParams, TurnID};
+use map_model::{IntersectionID, Map, PathConstraints, RoadID, RoutingParams, TurnID};
 use widgetry::mapspace::{DrawUnzoomedShapes, ToggleZoomed};
 use widgetry::{EventCtx, GeomBatch, GfxCtx};
 
@@ -200,7 +200,7 @@ impl DiagonalFilter {
     /// The caller must call this in a `before_edit` / `after_edit` "transaction."
     pub fn cycle_through_alternatives(app: &mut App, i: IntersectionID) {
         let map = &app.map;
-        let roads = map.get_i(i).get_roads_sorted_by_incoming_angle(map);
+        let mut roads = map.get_i(i).get_roads_sorted_by_incoming_angle(map);
 
         if roads.len() == 4 {
             // 4-way intersections are the only place where true diagonal filters can be placed
@@ -224,6 +224,16 @@ impl DiagonalFilter {
         } else if roads.len() > 1 {
             // Diagonal filters elsewhere don't really make sense. They're equivalent to filtering
             // one road. Just cycle through those.
+
+            // But skip roads that're aren't filterable
+            roads.retain(|r| {
+                let road = app.map.get_r(*r);
+                // Include non-driveable roads in this check, since we haven't filtered those out yet
+                road.oneway_for_driving().is_none()
+                    && !road.is_deadend(&app.map)
+                    && PathConstraints::Car.can_use_road(road, &app.map)
+            });
+
             let mut add_filter_to = None;
             if let Some(idx) = roads
                 .iter()