diff --git a/egregoria/src/map/objects/intersection.rs b/egregoria/src/map/objects/intersection.rs
index 25935c15..2ef91253 100644
--- a/egregoria/src/map/objects/intersection.rs
+++ b/egregoria/src/map/objects/intersection.rs
@@ -144,21 +144,23 @@ impl Intersection {
             let r1 = &roads[r1_id];
             let r2 = &roads[r2_id];
 
-            let width1 = r1.width * 0.5;
-            let width2 = r2.width * 0.5;
+            let min_dist =
+                Self::interface_calc(r1.width, r2.width, r1.dir_from(id), r2.dir_from(id));
+            roads[r1_id].max_interface(id, min_dist);
+            roads[r2_id].max_interface(id, min_dist);
+        }
+    }
 
-            let w = width1.hypot(width2);
+    fn interface_calc(w1: f32, w2: f32, dir1: Vec2, dir2: Vec2) -> f32 {
+        let hwidth1 = w1 * 0.5;
+        let hwidth2 = w2 * 0.5;
 
-            let dir1 = r1.dir_from(id);
-            let dir2 = r2.dir_from(id);
+        let w = hwidth1.hypot(hwidth2);
 
-            let d = dir1.dot(dir2).clamp(0.0, 1.0);
-            let sin = (1.0 - d * d).sqrt();
+        let d = dir1.dot(dir2).clamp(0.0, 1.0);
+        let sin = (1.0 - d * d).sqrt();
 
-            let min_dist = w * 1.1 / sin;
-            roads[r1_id].max_interface(id, min_dist);
-            roads[r2_id].max_interface(id, min_dist);
-        }
+        (w * 1.1 / sin).min(30.0)
     }
 
     pub fn empty_interface(width: f32) -> f32 {
@@ -170,16 +172,7 @@ impl Intersection {
         let id = self.id;
         for &r1_id in &self.roads {
             let r1 = unwrap_cont!(roads.get(r1_id));
-
-            let width1 = r1.width * 0.5;
-            let w = width1.hypot(width);
-            let dir1 = r1.dir_from(id);
-
-            let d = dir1.dot(dir).clamp(0.0, 1.0);
-            let sin = (1.0 - d * d).sqrt();
-
-            let min_dist = w * 1.1 / sin;
-            max_inter = max_inter.max(min_dist);
+            max_inter = max_inter.max(Self::interface_calc(r1.width, width, r1.dir_from(id), dir));
         }
         max_inter
     }
diff --git a/native_app/src/gui/roadbuild.rs b/native_app/src/gui/roadbuild.rs
index e0eaf290..c0b207b8 100644
--- a/native_app/src/gui/roadbuild.rs
+++ b/native_app/src/gui/roadbuild.rs
@@ -261,7 +261,7 @@ pub fn roadbuild(goria: &Egregoria, uiworld: &mut UiWorld) {
 
 fn check_angle(map: &Map, from: MapProject, to: Vec2, is_rail: bool) -> bool {
     let max_turn_angle = if is_rail {
-        10.0 * std::f32::consts::PI / 180.0
+        1.0 * std::f32::consts::PI / 180.0
     } else {
         30.0 * std::f32::consts::PI / 180.0
     };