Index: src/newgrf_engine.cpp
===================================================================
--- src/newgrf_engine.cpp	(Revision 19525)
+++ src/newgrf_engine.cpp	(Arbeitskopie)
@@ -607,21 +607,28 @@
 			}
 
 		case 0x45: { // Curvature info
-			/* Format: xxxTxBxF
+			/* Format: xttTbBfF
 			 * F - previous wagon to current wagon, 0 if vehicle is first
 			 * B - current wagon to next wagon, 0 if wagon is last
 			 * T - previous wagon to next wagon, 0 in an S-bend
+			 * tt,b,f returns the amount of dH between the adjacent wagon pairs. The dH is the difference in height between the surrounding vehicles
 			 */
 			if (v->type != VEH_TRAIN && v->type != VEH_ROAD) return 0;
 
 			const Vehicle *u_p = v->Previous();
 			const Vehicle *u_n = v->Next();
 			DirDiff f = (u_p == NULL) ?  DIRDIFF_SAME : DirDifference(u_p->direction, v->direction);
+			int    fz = (u_p == NULL) ?  0 : u_p->z_pos - v->z_pos;
 			DirDiff b = (u_n == NULL) ?  DIRDIFF_SAME : DirDifference(v->direction, u_n->direction);
+			int    bz = (u_p == NULL) ?  0 : v->z_pos - u_n->z_pos;
 			DirDiff t = ChangeDirDiff(f, b);
+			int    tz = fz-bz;
 
-			return ((t > DIRDIFF_REVERSE ? t | 8 : t) << 16) |
+			return ((tz & 0xFF) << 20) |
+			       ((t > DIRDIFF_REVERSE ? t | 8 : t) << 16) |
+			       ((bz & 0xF)  << 12) |
 			       ((b > DIRDIFF_REVERSE ? b | 8 : b) <<  8) |
+			       ((fz & 0xF)  <<  4) |
 			       ( f > DIRDIFF_REVERSE ? f | 8 : f);
 		}