From 777585317a2b05b35f22bec5d370ce7ddc37e65e Mon Sep 17 00:00:00 2001
From: Bryan Housel <bryan@mapbox.com>
Date: Mon, 12 Feb 2018 14:42:39 -0500
Subject: [PATCH] Better inference of u-turns via way

---
 modules/osm/intersection.js | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/modules/osm/intersection.js b/modules/osm/intersection.js
index 409471add..4f91320e9 100644
--- a/modules/osm/intersection.js
+++ b/modules/osm/intersection.js
@@ -604,7 +604,9 @@ export function osmInferRestriction(graph, from, to, projection) {
     if (fromNode === toNode)
         return 'no_u_turn';
     if ((angle < 23 || angle > 336) && fromOneWay && toOneWay)
-        return 'no_u_turn';
+        return 'no_u_turn';   // wider tolerance for u-turn if both ways are oneway
+    if ((angle < 40 || angle > 319) && fromOneWay && toOneWay && from.vertex !== to.vertex)
+        return 'no_u_turn';   // even wider tolerance for u-turn if there is a via way (from !== to)
     if (angle < 158)
         return 'no_right_turn';
     if (angle > 202)