diff --git a/game/src/ltn/mod.rs b/game/src/ltn/mod.rs
index 9546081693..93c769a47a 100644
--- a/game/src/ltn/mod.rs
+++ b/game/src/ltn/mod.rs
@@ -2,7 +2,7 @@ use std::collections::{BTreeMap, BTreeSet};
 
 use geom::{Circle, Distance, Line, Polygon};
 use map_gui::tools::DrawRoadLabels;
-use map_model::{IntersectionID, Map, Perimeter, RoadID};
+use map_model::{IntersectionID, Map, Perimeter, RoadID, RoutingParams, TurnID};
 use widgetry::mapspace::ToggleZoomed;
 use widgetry::{Color, Drawable, EventCtx, GeomBatch};
 
@@ -41,6 +41,25 @@ pub struct ModalFilters {
     pub intersections: BTreeMap<IntersectionID, DiagonalFilter>,
 }
 
+impl ModalFilters {
+    /// Modify RoutingParams to respect these modal filters
+    pub fn update_routing_params(&self, params: &mut RoutingParams) {
+        params.avoid_roads.extend(self.roads.keys().cloned());
+        for filter in self.intersections.values() {
+            params
+                .avoid_movements_between
+                .extend(filter.avoid_movements_between_roads());
+        }
+    }
+
+    pub fn allows_turn(&self, t: TurnID) -> bool {
+        if let Some(filter) = self.intersections.get(&t.parent) {
+            return filter.allows_turn(t.src.road, t.dst.road);
+        }
+        true
+    }
+}
+
 /// A diagonal filter exists in an intersection. It's defined by two roads (the order is
 /// arbitrary). When all of the intersection's roads are sorted in clockwise order, this pair of
 /// roads splits the ordering into two groups. Turns in each group are still possible, but not
diff --git a/game/src/ltn/rat_runs.rs b/game/src/ltn/rat_runs.rs
index 63dd277b5c..f3a0c3f8bb 100644
--- a/game/src/ltn/rat_runs.rs
+++ b/game/src/ltn/rat_runs.rs
@@ -38,16 +38,30 @@ pub fn find_rat_runs(
         }
     }
 
+    let mut params = map.routing_params().clone();
+    modal_filters.update_routing_params(&mut params);
+    let cache_custom = true;
     let mut paths: Vec<Path> = timer
         .parallelize(
             "calculate paths between entrances and exits",
             requests,
-            |req| map.pathfind(req),
+            |req| map.pathfind_with_params(req, &params, cache_custom),
         )
         .into_iter()
         .flatten()
         .collect();
 
+    // update_routing_params heavily penalizes crossing modal filters, but it doesn't prevent it
+    // completely! So strip out paths that were forced to cross a filter.
+    paths.retain(|path| {
+        !path.get_steps().iter().any(|step| match step {
+            PathStep::Lane(l) => modal_filters.roads.contains_key(&l.road),
+            PathStep::Turn(t) => !modal_filters.allows_turn(*t),
+            // Car paths don't make contraflow movements
+            _ => unreachable!(),
+        })
+    });
+
     // Some paths wind up partly using perimeter roads (or even things outside the neighborhood
     // entirely). Sort by "worse" paths that spend more time inside.
     paths.sort_by_key(|path| {
diff --git a/game/src/ltn/route.rs b/game/src/ltn/route.rs
index 20fa87b245..b674e9ead4 100644
--- a/game/src/ltn/route.rs
+++ b/game/src/ltn/route.rs
@@ -87,14 +87,7 @@ impl RoutePlanner {
         // First the route respecting the filters
         let (total_time_after, total_dist_after) = {
             let mut params = map.routing_params().clone();
-            params
-                .avoid_roads
-                .extend(app.session.modal_filters.roads.keys().cloned());
-            for filter in app.session.modal_filters.intersections.values() {
-                params
-                    .avoid_movements_between
-                    .extend(filter.avoid_movements_between_roads());
-            }
+            app.session.modal_filters.update_routing_params(&mut params);
             params.main_road_penalty = self.panel.spinner::<RoundedF64>("main road penalty").0;
             let cache_custom = true;