From c2e9eb7d7bddf40236434733073ca944a13f1d74 Mon Sep 17 00:00:00 2001
From: Darkvater <darkvater@openttd.org>
Date: Sat, 20 May 2006 20:16:08 +0000
Subject: [PATCH] (svn r4931) - Backport from trunk (r4766):   Vehicles on a
 sloped tile under a bridge were affected by the bridge speed limit

---
 tunnelbridge_cmd.c | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/tunnelbridge_cmd.c b/tunnelbridge_cmd.c
index fa25cc28af..aba652c0c7 100644
--- a/tunnelbridge_cmd.c
+++ b/tunnelbridge_cmd.c
@@ -1208,6 +1208,23 @@ static inline DiagDirection GetBridgeRampDirection(TileIndex t) {return (DiagDir
 static inline bool IsTransportUnderBridge(TileIndex t) {return HASBIT(_m[t].m5, 5);}
 static inline uint GetBridgeAxis(TileIndex t) {return GB(_m[t].m5, 0, 1);}
 
+static uint GetTileMaxZ(TileIndex t)
+{
+	uint max;
+	uint h;
+
+	h = TileHeight(t);
+	max = h;
+	h = TileHeight(t + TileDiffXY(1, 0));
+	if (h > max) max = h;
+	h = TileHeight(t + TileDiffXY(0, 1));
+	if (h > max) max = h;
+	h = TileHeight(t + TileDiffXY(1, 1));
+	if (h > max) max = h;
+	return max * 8;
+}
+
+
 static uint GetSlopeZ_TunnelBridge(const TileInfo* ti)
 {
 	TileIndex tile = ti->tile;
@@ -1522,12 +1539,7 @@ static uint32 VehicleEnter_TunnelBridge(Vehicle *v, TileIndex tile, int x, int y
 		}
 	} else if (_m[tile].m5 & 0x80) {
 		if (v->type == VEH_Road || (v->type == VEH_Train && IsFrontEngine(v))) {
-			uint h;
-
-			if (GetTileSlope(tile, &h) != 0)
-				h += 8; // Compensate for possible foundation
-			if (!(_m[tile].m5 & 0x40) || // start/end tile of bridge
-					myabs(h - v->z_pos) > 2) { // high above the ground -> on the bridge
+			if (IsBridgeRamp(tile) || v->z_pos > GetTileMaxZ(tile)) {
 				/* modify speed of vehicle */
 				uint16 spd = _bridge[GetBridgeType(tile)].speed;
 				if (v->type == VEH_Road) spd *= 2;