summaryrefslogtreecommitdiff
path: root/src/tunnelbridge_cmd.cpp
blob: 6e8b88cbd486d80620e68ea1a53988f198c41931 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
/* $Id$ */

/** @file tunnelbridge_cmd.cpp
 * This file deals with tunnels and bridges (non-gui stuff)
 * @todo seperate this file into two
 */

#include "stdafx.h"
#include "openttd.h"
#include "rail_map.h"
#include "landscape.h"
#include "unmovable_map.h"
#include "viewport_func.h"
#include "command_func.h"
#include "town.h"
#include "variables.h"
#include "train.h"
#include "water_map.h"
#include "yapf/yapf.h"
#include "newgrf_sound.h"
#include "autoslope.h"
#include "tunnelbridge_map.h"
#include "strings_func.h"
#include "date_func.h"
#include "functions.h"
#include "vehicle_func.h"
#include "sound_func.h"
#include "tunnelbridge.h"
#include "engine_base.h"
#include "cheat_type.h"
#include "elrail_func.h"
#include "landscape_type.h"

#include "table/sprites.h"
#include "table/strings.h"
#include "table/bridge_land.h"

BridgeSpec _bridge[MAX_BRIDGES];
TileIndex _build_tunnel_endtile;

/** Reset the data been eventually changed by the grf loaded. */
void ResetBridges()
{
	/* First, free sprite table data */
	for (BridgeType i = 0; i < MAX_BRIDGES; i++) {
		if (_bridge[i].sprite_table != NULL) {
			for (BridgePieces j = BRIDGE_PIECE_NORTH; j < BRIDGE_PIECE_INVALID; j++) free(_bridge[i].sprite_table[j]);
			free(_bridge[i].sprite_table);
		}
	}

	/* Then, wipe out current bidges */
	memset(&_bridge, 0, sizeof(_bridge));
	/* And finally, reinstall default data */
	memcpy(&_bridge, &_orig_bridge, sizeof(_orig_bridge));
}

/** calculate the price factor for building a long bridge.
 * basically the cost delta is 1,1, 1, 2,2, 3,3,3, 4,4,4,4, 5,5,5,5,5, 6,6,6,6,6,6,  7,7,7,7,7,7,7,  8,8,8,8,8,8,8,8,
 */
int CalcBridgeLenCostFactor(int x)
{
	int n;
	int r;

	if (x < 2) return x;
	x -= 2;
	for (n = 0, r = 2;; n++) {
		if (x <= n) return r + x * n;
		r += n * n;
		x -= n;
	}
}

Foundation GetBridgeFoundation(Slope tileh, Axis axis)
{
	if ((tileh == SLOPE_FLAT) ||
	    (((tileh == SLOPE_NE) || (tileh == SLOPE_SW)) && (axis == AXIS_X)) ||
	    (((tileh == SLOPE_NW) || (tileh == SLOPE_SE)) && (axis == AXIS_Y))) return FOUNDATION_NONE;

	return (HasSlopeHighestCorner(tileh) ? InclinedFoundation(axis) : FlatteningFoundation(tileh));
}

/**
 * Determines if the track on a bridge ramp is flat or goes up/down.
 *
 * @param tileh Slope of the tile under the bridge head
 * @param axis Orientation of bridge
 * @return true iff the track is flat.
 */
bool HasBridgeFlatRamp(Slope tileh, Axis axis)
{
	ApplyFoundationToSlope(GetBridgeFoundation(tileh, axis), &tileh);
	/* If the foundation slope is flat the bridge has a non-flat ramp and vice versa. */
	return (tileh != SLOPE_FLAT);
}

static inline const PalSpriteID *GetBridgeSpriteTable(int index, BridgePieces table)
{
	const BridgeSpec *bridge = GetBridgeSpec(index);
	assert(table < BRIDGE_PIECE_INVALID);
	if (bridge->sprite_table == NULL || bridge->sprite_table[table] == NULL) {
		return _bridge_sprite_table[index][table];
	} else {
		return bridge->sprite_table[table];
	}
}


/**
 * Determines the foundation for the north bridge head, and tests if the resulting slope is valid.
 *
 * @param axis Axis of the bridge
 * @param tileh Slope of the tile under the north bridge head; returns slope on top of foundation
 * @param z TileZ corresponding to tileh, gets modified as well
 * @return Error or cost for bridge foundation
 */
static CommandCost CheckBridgeSlopeNorth(Axis axis, Slope *tileh, uint *z)
{
	Foundation f = GetBridgeFoundation(*tileh, axis);
	*z += ApplyFoundationToSlope(f, tileh);

	Slope valid_inclined = (axis == AXIS_X ? SLOPE_NE : SLOPE_NW);
	if ((*tileh != SLOPE_FLAT) && (*tileh != valid_inclined)) return CMD_ERROR;

	if (f == FOUNDATION_NONE) return CommandCost();

	return CommandCost(EXPENSES_CONSTRUCTION, _price.terraform);
}

/**
 * Determines the foundation for the south bridge head, and tests if the resulting slope is valid.
 *
 * @param axis Axis of the bridge
 * @param tileh Slope of the tile under the south bridge head; returns slope on top of foundation
 * @param z TileZ corresponding to tileh, gets modified as well
 * @return Error or cost for bridge foundation
 */
static CommandCost CheckBridgeSlopeSouth(Axis axis, Slope *tileh, uint *z)
{
	Foundation f = GetBridgeFoundation(*tileh, axis);
	*z += ApplyFoundationToSlope(f, tileh);

	Slope valid_inclined = (axis == AXIS_X ? SLOPE_SW : SLOPE_SE);
	if ((*tileh != SLOPE_FLAT) && (*tileh != valid_inclined)) return CMD_ERROR;

	if (f == FOUNDATION_NONE) return CommandCost();

	return CommandCost(EXPENSES_CONSTRUCTION, _price.terraform);
}

bool CheckBridge_Stuff(BridgeType bridge_type, uint bridge_len, DoCommandFlag flags)
{
	if (flags & DC_QUERY_COST) {
		return bridge_len <= (_settings_game.construction.longbridges ? 100U : 16U);
	}

	if (bridge_type >= MAX_BRIDGES) return false;

	const BridgeSpec *b = GetBridgeSpec(bridge_type);
	if (b->avail_year > _cur_year) return false;

	uint max = b->max_length;
	if (max >= 16 && _settings_game.construction.longbridges) max = 100;

	return b->min_length <= bridge_len && bridge_len <= max;
}

/** Build a Bridge
 * @param end_tile end tile
 * @param flags type of operation
 * @param p1 packed start tile coords (~ dx)
 * @param p2 various bitstuffed elements
 * - p2 = (bit  0- 7) - bridge type (hi bh)
 * - p2 = (bit  8-14) - rail type or road types.
 * - p2 = (bit 15-16) - transport type.
 */
CommandCost CmdBuildBridge(TileIndex end_tile, DoCommandFlag flags, uint32 p1, uint32 p2, const char *text)
{
	BridgeType bridge_type;
	RailType railtype = INVALID_RAILTYPE;
	RoadTypes roadtypes = ROADTYPES_NONE;
	uint x;
	uint y;
	uint sx;
	uint sy;
	TileIndex tile_start;
	TileIndex tile_end;
	Slope tileh_start;
	Slope tileh_end;
	uint z_start;
	uint z_end;
	TileIndex tile;
	TileIndexDiff delta;
	uint bridge_len;
	Axis direction;
	CommandCost cost(EXPENSES_CONSTRUCTION);
	CommandCost ret;
	bool replace_bridge = false;
	BridgeType replaced_bridge_type;
	TransportType transport_type;

	/* unpack parameters */
	bridge_type = GB(p2, 0, 8);

	if (p1 >= MapSize()) return CMD_ERROR;

	transport_type = (TransportType)GB(p2, 15, 2);

	/* type of bridge */
	switch (transport_type) {
		case TRANSPORT_ROAD:
			roadtypes = (RoadTypes)GB(p2, 8, 2);
			if (!AreValidRoadTypes(roadtypes) || !HasRoadTypesAvail(_current_company, roadtypes)) return CMD_ERROR;
			break;

		case TRANSPORT_RAIL:
			railtype = (RailType)GB(p2, 8, 7);
			if (!ValParamRailtype(railtype)) return CMD_ERROR;
			break;

		case TRANSPORT_WATER:
			break;

		default:
			/* Airports don't have tunnels. */
			return CMD_ERROR;
	}

	x = TileX(end_tile);
	y = TileY(end_tile);
	sx = TileX(p1);
	sy = TileY(p1);

	/* check if valid, and make sure that (x,y) are smaller than (sx,sy) */
	if (x == sx) {
		if (y == sy) return_cmd_error(STR_ERROR_CANNOT_START_AND_END_ON);
		direction = AXIS_Y;
		if (y > sy) Swap(y, sy);
	} else if (y == sy) {
		direction = AXIS_X;
		if (x > sx) Swap(x, sx);
	} else {
		return_cmd_error(STR_ERROR_START_AND_END_MUST_BE_IN);
	}

	bridge_len = sx + sy - x - y - 1;
	if (transport_type != TRANSPORT_WATER) {
		/* set and test bridge length, availability */
		if (!CheckBridge_Stuff(bridge_type, bridge_len, flags)) return_cmd_error(STR_ERROR_CAN_T_BUILD_BRIDGE_HERE);
	}

	/* retrieve landscape height and ensure it's on land */
	tile_start = TileXY(x, y);
	tile_end = TileXY(sx, sy);
	if (IsWaterTile(tile_start) || IsWaterTile(tile_end)) {
		return_cmd_error(STR_ERROR_ENDS_OF_BRIDGE_MUST_BOTH);
	}

	tileh_start = GetTileSlope(tile_start, &z_start);
	tileh_end = GetTileSlope(tile_end, &z_end);

	CommandCost terraform_cost_north = CheckBridgeSlopeNorth(direction, &tileh_start, &z_start);
	CommandCost terraform_cost_south = CheckBridgeSlopeSouth(direction, &tileh_end,   &z_end);

	if (z_start != z_end) return_cmd_error(STR_BRIDGEHEADS_NOT_SAME_HEIGHT);

	if (IsBridgeTile(tile_start) && IsBridgeTile(tile_end) &&
			GetOtherBridgeEnd(tile_start) == tile_end &&
			GetTunnelBridgeTransportType(tile_start) == transport_type) {
		/* Replace a current bridge. */

		/* If this is a railway bridge, make sure the railtypes match. */
		if (transport_type == TRANSPORT_RAIL && GetRailType(tile_start) != railtype) {
			return_cmd_error(STR_ERROR_MUST_DEMOLISH_BRIDGE_FIRST);
		}

		/* Do not replace town bridges with lower speed bridges. */
		if (!(flags & DC_QUERY_COST) && IsTileOwner(tile_start, OWNER_TOWN) &&
				GetBridgeSpec(bridge_type)->speed < GetBridgeSpec(GetBridgeType(tile_start))->speed) {
			Town *t = ClosestTownFromTile(tile_start, UINT_MAX);

			if (t == NULL) {
				return CMD_ERROR;
			} else {
				SetDParam(0, t->index);
				return_cmd_error(STR_ERROR_LOCAL_AUTHORITY_REFUSES_TO_ALLOW_THIS);
			}
		}

		/* Do not replace the bridge with the same bridge type. */
		if (!(flags & DC_QUERY_COST) && bridge_type == GetBridgeType(tile_start)) {
			return_cmd_error(STR_ERROR_ALREADY_BUILT);
		}

		/* Do not allow replacing another company's bridges. */
		if (!IsTileOwner(tile_start, _current_company) && !IsTileOwner(tile_start, OWNER_TOWN)) {
			return_cmd_error(STR_ERROR_AREA_IS_OWNED_BY_ANOTHER);
		}

		cost.AddCost((bridge_len + 1) * _price.clear_bridge); // The cost of clearing the current bridge.
		replace_bridge = true;
		replaced_bridge_type = GetBridgeType(tile_start);

		/* Do not remove road types when upgrading a bridge */
		roadtypes |= GetRoadTypes(tile_start);
	} else {
		/* Build a new bridge. */

		bool allow_on_slopes = (_settings_game.construction.build_on_slopes && transport_type != TRANSPORT_WATER);

		/* Try and clear the start landscape */
		ret = DoCommand(tile_start, 0, 0, flags, CMD_LANDSCAPE_CLEAR);
		if (CmdFailed(ret)) return ret;
		cost = ret;

		if (CmdFailed(terraform_cost_north) || (terraform_cost_north.GetCost() != 0 && !allow_on_slopes))
			return_cmd_error(STR_ERROR_LAND_SLOPED_IN_WRONG_DIRECTION);
		cost.AddCost(terraform_cost_north);

		/* Try and clear the end landscape */
		ret = DoCommand(tile_end, 0, 0, flags, CMD_LANDSCAPE_CLEAR);
		if (CmdFailed(ret)) return ret;
		cost.AddCost(ret);

		/* false - end tile slope check */
		if (CmdFailed(terraform_cost_south) || (terraform_cost_south.GetCost() != 0 && !allow_on_slopes))
			return_cmd_error(STR_ERROR_LAND_SLOPED_IN_WRONG_DIRECTION);
		cost.AddCost(terraform_cost_south);

		if (transport_type == TRANSPORT_WATER && (tileh_start == SLOPE_FLAT || tileh_end == SLOPE_FLAT)) return_cmd_error(STR_ERROR_LAND_SLOPED_IN_WRONG_DIRECTION);
	}

	if (!replace_bridge) {
		TileIndex Heads[] = {tile_start, tile_end};
		int i;

		for (i = 0; i < 2; i++) {
			if (MayHaveBridgeAbove(Heads[i])) {
				if (IsBridgeAbove(Heads[i])) {
					TileIndex north_head = GetNorthernBridgeEnd(Heads[i]);

					if (direction == GetBridgeAxis(Heads[i])) return_cmd_error(STR_ERROR_MUST_DEMOLISH_BRIDGE_FIRST);

					if (z_start + TILE_HEIGHT == GetBridgeHeight(north_head)) {
						return_cmd_error(STR_ERROR_MUST_DEMOLISH_BRIDGE_FIRST);
					}
				}
			}
		}
	}

	/* do the drill? */
	if (flags & DC_EXEC) {
		DiagDirection dir = AxisToDiagDir(direction);
		Owner owner = replace_bridge ? GetTileOwner(tile_start) : _current_company;

		switch (transport_type) {
			case TRANSPORT_RAIL:
				MakeRailBridgeRamp(tile_start, owner, bridge_type, dir,                 railtype);
				MakeRailBridgeRamp(tile_end,   owner, bridge_type, ReverseDiagDir(dir), railtype);
				break;

			case TRANSPORT_ROAD:
				MakeRoadBridgeRamp(tile_start, owner, bridge_type, dir,                 roadtypes);
				MakeRoadBridgeRamp(tile_end,   owner, bridge_type, ReverseDiagDir(dir), roadtypes);
				break;

			case TRANSPORT_WATER:
				MakeAqueductBridgeRamp(tile_start, owner, dir);
				MakeAqueductBridgeRamp(tile_end,   owner, ReverseDiagDir(dir));
				break;

			default:
				NOT_REACHED();
				break;
		}
		MarkTileDirtyByTile(tile_start);
		MarkTileDirtyByTile(tile_end);
	}

	delta = (direction == AXIS_X ? TileDiffXY(1, 0) : TileDiffXY(0, 1));
	for (tile = tile_start + delta; tile != tile_end; tile += delta) {
		if (GetTileMaxZ(tile) > z_start) return_cmd_error(STR_BRIDGE_TOO_LOW_FOR_TERRAIN);

		if (MayHaveBridgeAbove(tile) && IsBridgeAbove(tile) && !replace_bridge) {
			/* Disallow crossing bridges for the time being */
			return_cmd_error(STR_ERROR_MUST_DEMOLISH_BRIDGE_FIRST);
		}

		switch (GetTileType(tile)) {
			case MP_WATER:
				if (!IsWater(tile) && !IsCoast(tile)) goto not_valid_below;
				break;

			case MP_RAILWAY:
				if (!IsPlainRailTile(tile)) goto not_valid_below;
				break;

			case MP_ROAD:
				if (IsRoadDepot(tile)) goto not_valid_below;
				break;

			case MP_TUNNELBRIDGE:
				if (IsTunnel(tile)) break;
				if (replace_bridge) break;
				if (direction == DiagDirToAxis(GetTunnelBridgeDirection(tile))) goto not_valid_below;
				if (z_start < GetBridgeHeight(tile)) goto not_valid_below;
				break;

			case MP_UNMOVABLE:
				if (!IsOwnedLand(tile)) goto not_valid_below;
				break;

			case MP_CLEAR:
				break;

			default:
not_valid_below:;
				/* try and clear the middle landscape */
				ret = DoCommand(tile, 0, 0, flags, CMD_LANDSCAPE_CLEAR);
				if (CmdFailed(ret)) return ret;
				cost.AddCost(ret);
				break;
		}

		if (flags & DC_EXEC) {
			SetBridgeMiddle(tile, direction);
			MarkTileDirtyByTile(tile);
		}
	}

	if (flags & DC_EXEC && transport_type == TRANSPORT_RAIL) {
		Track track = AxisToTrack(direction);
		AddSideToSignalBuffer(tile_start, INVALID_DIAGDIR, _current_company);
		YapfNotifyTrackLayoutChange(tile_start, track);
	}

	/* for human player that builds the bridge he gets a selection to choose from bridges (DC_QUERY_COST)
	 * It's unnecessary to execute this command every time for every bridge. So it is done only
	 * and cost is computed in "bridge_gui.c". For AI, Towns this has to be of course calculated
	 */
	if (!(flags & DC_QUERY_COST) || (IsValidCompanyID(_current_company) && GetCompany(_current_company)->is_ai)) {
		bridge_len += 2; // begin and end tiles/ramps

		if (IsValidCompanyID(_current_company))
			bridge_len = CalcBridgeLenCostFactor(bridge_len);

		cost.AddCost((int64)bridge_len * _price.build_bridge * GetBridgeSpec(bridge_type)->price >> 8);

		/* Aqueducts are a little more expensive. */
		if (transport_type == TRANSPORT_WATER) cost.AddCost((int64)bridge_len * _price.clear_water);
	}

	return cost;
}


/** Build Tunnel.
 * @param start_tile start tile of tunnel
 * @param flags type of operation
 * @param p1 railtype or roadtypes. bit 9 set means road tunnel
 * @param p2 unused
 */
CommandCost CmdBuildTunnel(TileIndex start_tile, DoCommandFlag flags, uint32 p1, uint32 p2, const char *text)
{
	TileIndexDiff delta;
	TileIndex end_tile;
	DiagDirection direction;
	Slope start_tileh;
	Slope end_tileh;
	TransportType transport_type = (TransportType)GB(p1, 9, 1);
	uint start_z;
	uint end_z;
	CommandCost cost(EXPENSES_CONSTRUCTION);
	CommandCost ret;

	_build_tunnel_endtile = 0;
	if (transport_type == TRANSPORT_RAIL) {
		if (!ValParamRailtype((RailType)p1)) return CMD_ERROR;
	} else {
		const RoadTypes rts = (RoadTypes)GB(p1, 0, 2);
		if (!AreValidRoadTypes(rts) || !HasRoadTypesAvail(_current_company, rts)) return CMD_ERROR;
	}

	start_tileh = GetTileSlope(start_tile, &start_z);
	direction = GetInclinedSlopeDirection(start_tileh);
	if (direction == INVALID_DIAGDIR) return_cmd_error(STR_ERROR_SITE_UNSUITABLE_FOR_TUNNEL);

	if (IsWaterTile(start_tile)) return_cmd_error(STR_ERROR_CAN_T_BUILD_ON_WATER);

	ret = DoCommand(start_tile, 0, 0, flags, CMD_LANDSCAPE_CLEAR);
	if (CmdFailed(ret)) return ret;

	/* XXX - do NOT change 'ret' in the loop, as it is used as the price
	 * for the clearing of the entrance of the tunnel. Assigning it to
	 * cost before the loop will yield different costs depending on start-
	 * position, because of increased-cost-by-length: 'cost += cost >> 3' */

	delta = TileOffsByDiagDir(direction);
	DiagDirection tunnel_in_way_dir;
	if (DiagDirToAxis(direction) == AXIS_Y) {
		tunnel_in_way_dir = (TileX(start_tile) < (MapMaxX() / 2)) ? DIAGDIR_SW : DIAGDIR_NE;
	} else {
		tunnel_in_way_dir = (TileY(start_tile) < (MapMaxX() / 2)) ? DIAGDIR_SE : DIAGDIR_NW;
	}

	end_tile = start_tile;

	/** Tile shift coeficient. Will decrease for very long tunnels to avoid exponential growth of price*/
	int tiles_coef = 3;
	/** Number of tiles from start of tunnel */
	int tiles = 0;
	/** Number of tiles at which the cost increase coefficient per tile is halved */
	int tiles_bump = 25;

	for (;;) {
		end_tile += delta;
		if (!IsValidTile(end_tile)) return_cmd_error(STR_TUNNEL_THROUGH_MAP_BORDER);
		end_tileh = GetTileSlope(end_tile, &end_z);

		if (start_z == end_z) break;

		if (!_cheats.crossing_tunnels.value && IsTunnelInWayDir(end_tile, start_z, tunnel_in_way_dir)) {
			return_cmd_error(STR_ERROR_ANOTHER_TUNNEL_IN_THE_WAY);
		}

		tiles++;
		if (tiles == tiles_bump) {
			tiles_coef++;
			tiles_bump *= 2;
		}

		cost.AddCost(_price.build_tunnel);
		cost.AddCost(cost.GetCost() >> tiles_coef); // add a multiplier for longer tunnels
	}

	/* Add the cost of the entrance */
	cost.AddCost(_price.build_tunnel);
	cost.AddCost(ret);

	/* if the command fails from here on we want the end tile to be highlighted */
	_build_tunnel_endtile = end_tile;

	if (IsWaterTile(end_tile)) return_cmd_error(STR_ERROR_CAN_T_BUILD_ON_WATER);

	/* slope of end tile must be complementary to the slope of the start tile */
	if (end_tileh != ComplementSlope(start_tileh)) {
		/* Check if there is a structure on the terraformed tile. Do not add the cost, that will be done by the terraforming
		 * Note: Currently the town rating is also affected by this clearing-test. So effectivly the player is punished twice for clearing
		 *       the tree on end_tile.
		 */
		ret = DoCommand(end_tile, 0, 0, DC_AUTO, CMD_LANDSCAPE_CLEAR);
		if (CmdFailed(ret)) return_cmd_error(STR_ERROR_UNABLE_TO_EXCAVATE_LAND);

		ret = DoCommand(end_tile, end_tileh & start_tileh, 0, flags, CMD_TERRAFORM_LAND);
		if (CmdFailed(ret)) return_cmd_error(STR_ERROR_UNABLE_TO_EXCAVATE_LAND);
	} else {
		ret = DoCommand(end_tile, 0, 0, flags, CMD_LANDSCAPE_CLEAR);
		if (CmdFailed(ret)) return ret;
	}
	cost.AddCost(_price.build_tunnel);
	cost.AddCost(ret);

	if (flags & DC_EXEC) {
		if (transport_type == TRANSPORT_RAIL) {
			MakeRailTunnel(start_tile, _current_company, direction,                 (RailType)GB(p1, 0, 4));
			MakeRailTunnel(end_tile,   _current_company, ReverseDiagDir(direction), (RailType)GB(p1, 0, 4));
			AddSideToSignalBuffer(start_tile, INVALID_DIAGDIR, _current_company);
			YapfNotifyTrackLayoutChange(start_tile, DiagDirToDiagTrack(direction));
		} else {
			MakeRoadTunnel(start_tile, _current_company, direction,                 (RoadTypes)GB(p1, 0, 2));
			MakeRoadTunnel(end_tile,   _current_company, ReverseDiagDir(direction), (RoadTypes)GB(p1, 0, 2));
		}
	}

	return cost;
}


static inline bool CheckAllowRemoveTunnelBridge(TileIndex tile)
{
	/* Floods can remove anything as well as the scenario editor */
	if (_current_company == OWNER_WATER || _game_mode == GM_EDITOR) return true;

	switch (GetTunnelBridgeTransportType(tile)) {
		case TRANSPORT_ROAD: {
			RoadTypes rts = GetRoadTypes(tile);
			Owner road_owner = _current_company;
			Owner tram_owner = _current_company;

			if (HasBit(rts, ROADTYPE_ROAD)) road_owner = GetRoadOwner(tile, ROADTYPE_ROAD);
			if (HasBit(rts, ROADTYPE_TRAM)) tram_owner = GetRoadOwner(tile, ROADTYPE_TRAM);

			/* We can remove unowned road and if the town allows it */
			if (road_owner == OWNER_TOWN && !(_settings_game.construction.extra_dynamite || _cheats.magic_bulldozer.value)) return CheckTileOwnership(tile);
			if (road_owner == OWNER_NONE || road_owner == OWNER_TOWN) road_owner = _current_company;
			if (tram_owner == OWNER_NONE) tram_owner = _current_company;

			return CheckOwnership(road_owner) && CheckOwnership(tram_owner);
		}

		case TRANSPORT_RAIL:
		case TRANSPORT_WATER:
			return CheckOwnership(GetTileOwner(tile));

		default: NOT_REACHED();
	}
}

static CommandCost DoClearTunnel(TileIndex tile, DoCommandFlag flags)
{
	Town *t = NULL;
	TileIndex endtile;

	if (!CheckAllowRemoveTunnelBridge(tile)) return CMD_ERROR;

	endtile = GetOtherTunnelEnd(tile);

	if (HasVehicleOnTunnelBridge(tile, endtile)) return CMD_ERROR;

	_build_tunnel_endtile = endtile;

	if (IsTileOwner(tile, OWNER_TOWN) && _game_mode != GM_EDITOR) {
		t = ClosestTownFromTile(tile, UINT_MAX); // town penalty rating

		/* Check if you are allowed to remove the tunnel owned by a town
		 * Removal depends on difficulty settings */
		if (!CheckforTownRating(flags, t, TUNNELBRIDGE_REMOVE)) {
			SetDParam(0, t->index);
			return_cmd_error(STR_ERROR_LOCAL_AUTHORITY_REFUSES_TO_ALLOW_THIS);
		}
	}

	/* checks if the owner is town then decrease town rating by RATING_TUNNEL_BRIDGE_DOWN_STEP until
	 * you have a "Poor" (0) town rating */
	if (IsTileOwner(tile, OWNER_TOWN) && _game_mode != GM_EDITOR) {
		ChangeTownRating(t, RATING_TUNNEL_BRIDGE_DOWN_STEP, RATING_TUNNEL_BRIDGE_MINIMUM, flags);
	}

	if (flags & DC_EXEC) {
		if (GetTunnelBridgeTransportType(tile) == TRANSPORT_RAIL) {
			/* We first need to request values before calling DoClearSquare */
			DiagDirection dir = GetTunnelBridgeDirection(tile);
			Track track = DiagDirToDiagTrack(dir);
			Owner owner = GetTileOwner(tile);

			Vehicle *v = NULL;
			if (GetTunnelBridgeReservation(tile)) {
				v = GetTrainForReservation(tile, track);
				if (v != NULL) FreeTrainTrackReservation(v);
			}

			DoClearSquare(tile);
			DoClearSquare(endtile);

			/* cannot use INVALID_DIAGDIR for signal update because the tunnel doesn't exist anymore */
			AddSideToSignalBuffer(tile,    ReverseDiagDir(dir), owner);
			AddSideToSignalBuffer(endtile, dir,                 owner);

			YapfNotifyTrackLayoutChange(tile,    track);
			YapfNotifyTrackLayoutChange(endtile, track);

			if (v != NULL) TryPathReserve(v);
		} else {
			DoClearSquare(tile);
			DoClearSquare(endtile);
		}
	}
	return CommandCost(EXPENSES_CONSTRUCTION, _price.clear_tunnel * (GetTunnelBridgeLength(tile, endtile) + 2));
}


static CommandCost DoClearBridge(TileIndex tile, DoCommandFlag flags)
{
	DiagDirection direction;
	TileIndexDiff delta;
	TileIndex endtile;
	Town *t = NULL;

	if (!CheckAllowRemoveTunnelBridge(tile)) return CMD_ERROR;

	endtile = GetOtherBridgeEnd(tile);

	if (HasVehicleOnTunnelBridge(tile, endtile)) return CMD_ERROR;

	direction = GetTunnelBridgeDirection(tile);
	delta = TileOffsByDiagDir(direction);

	if (IsTileOwner(tile, OWNER_TOWN) && _game_mode != GM_EDITOR) {
		t = ClosestTownFromTile(tile, UINT_MAX); // town penalty rating

		/* Check if you are allowed to remove the bridge owned by a town
		 * Removal depends on difficulty settings */
		if (!CheckforTownRating(flags, t, TUNNELBRIDGE_REMOVE)) {
			SetDParam(0, t->index);
			return_cmd_error(STR_ERROR_LOCAL_AUTHORITY_REFUSES_TO_ALLOW_THIS);
		}
	}

	/* checks if the owner is town then decrease town rating by RATING_TUNNEL_BRIDGE_DOWN_STEP until
	 * you have a "Poor" (0) town rating */
	if (IsTileOwner(tile, OWNER_TOWN) && _game_mode != GM_EDITOR) {
		ChangeTownRating(t, RATING_TUNNEL_BRIDGE_DOWN_STEP, RATING_TUNNEL_BRIDGE_MINIMUM, flags);
	}

	if (flags & DC_EXEC) {
		/* read this value before actual removal of bridge */
		bool rail = GetTunnelBridgeTransportType(tile) == TRANSPORT_RAIL;
		Owner owner = GetTileOwner(tile);
		uint height = GetBridgeHeight(tile);
		Vehicle *v = NULL;

		if (rail && GetTunnelBridgeReservation(tile)) {
			v = GetTrainForReservation(tile, DiagDirToDiagTrack(direction));
			if (v != NULL) FreeTrainTrackReservation(v);
		}

		DoClearSquare(tile);
		DoClearSquare(endtile);
		for (TileIndex c = tile + delta; c != endtile; c += delta) {
			/* do not let trees appear from 'nowhere' after removing bridge */
			if (IsNormalRoadTile(c) && GetRoadside(c) == ROADSIDE_TREES) {
				uint minz = GetTileMaxZ(c) + 3 * TILE_HEIGHT;
				if (height < minz) SetRoadside(c, ROADSIDE_PAVED);
			}
			ClearBridgeMiddle(c);
			MarkTileDirtyByTile(c);
		}

		if (rail) {
			/* cannot use INVALID_DIAGDIR for signal update because the bridge doesn't exist anymore */
			AddSideToSignalBuffer(tile,    ReverseDiagDir(direction), owner);
			AddSideToSignalBuffer(endtile, direction,                 owner);

			Track track = DiagDirToDiagTrack(direction);
			YapfNotifyTrackLayoutChange(tile,    track);
			YapfNotifyTrackLayoutChange(endtile, track);

			if (v != NULL) TryPathReserve(v, true);
		}
	}

	return CommandCost(EXPENSES_CONSTRUCTION, (GetTunnelBridgeLength(tile, endtile) + 2) * _price.clear_bridge);
}

static CommandCost ClearTile_TunnelBridge(TileIndex tile, DoCommandFlag flags)
{
	if (IsTunnel(tile)) {
		if (flags & DC_AUTO) return_cmd_error(STR_ERROR_MUST_DEMOLISH_TUNNEL_FIRST);
		return DoClearTunnel(tile, flags);
	} else { // IsBridge(tile)
		if (flags & DC_AUTO) return_cmd_error(STR_ERROR_MUST_DEMOLISH_BRIDGE_FIRST);
		return DoClearBridge(tile, flags);
	}

	return CMD_ERROR;
}

/**
 * Draws the pillars under high bridges.
 *
 * @param psid Image and palette of a bridge pillar.
 * @param ti #TileInfo of current bridge-middle-tile.
 * @param axis Orientation of bridge.
 * @param type Bridge type.
 * @param x Sprite X position of front pillar.
 * @param y Sprite Y position of front pillar.
 * @param z_bridge Absolute height of bridge bottom.
 */
static void DrawBridgePillars(const PalSpriteID *psid, const TileInfo *ti, Axis axis, bool drawfarpillar, int x, int y, int z_bridge)
{
	/* Do not draw bridge pillars if they are invisible */
	if (IsInvisibilitySet(TO_BRIDGES)) return;

	SpriteID image = psid->sprite;

	if (image != 0) {
		/* "side" specifies the side the pillars stand on.
		 * The length of the pillars is then set to the height of the bridge over the corners of this edge.
		 *
		 *                axis==AXIS_X  axis==AXIS_Y
		 *   side==false      SW            NW
		 *   side==true       NE            SE
		 *
		 * I have no clue, why this was done this way.
		 */
		bool side = HasBit(image, 0);

		/* "dir" means the edge the pillars stand on */
		DiagDirection dir = AxisToDiagDir(axis);
		if (side != (axis == AXIS_Y)) dir = ReverseDiagDir(dir);

		/* Determine ground height under pillars */
		int front_height = ti->z;
		int back_height = ti->z;
		GetSlopeZOnEdge(ti->tileh, dir, &front_height, &back_height);

		/* x and y size of bounding-box of pillars */
		int w = (axis == AXIS_X ? 16 : 2);
		int h = (axis == AXIS_X ? 2 : 16);
		/* sprite position of back facing pillar */
		int x_back = x - (axis == AXIS_X ? 0 : 9);
		int y_back = y - (axis == AXIS_X ? 9 : 0);

		for (int cur_z = z_bridge; cur_z >= front_height || cur_z >= back_height; cur_z -= TILE_HEIGHT) {
			/* Draw front facing pillar */
			if (cur_z >= front_height) {
				AddSortableSpriteToDraw(image, psid->pal, x, y, w, h, BB_HEIGHT_UNDER_BRIDGE - 5, cur_z, IsTransparencySet(TO_BRIDGES), 0, 0, -5);
			}

			/* Draw back facing pillar, but not the highest part directly under the bridge-floor */
			if (drawfarpillar && cur_z >= back_height && cur_z < z_bridge - TILE_HEIGHT) {
				AddSortableSpriteToDraw(image, psid->pal, x_back, y_back, w, h, BB_HEIGHT_UNDER_BRIDGE - 5, cur_z, IsTransparencySet(TO_BRIDGES), 0, 0, -5);
			}
		}
	}
}

/**
 * Draws the trambits over an already drawn (lower end) of a bridge.
 * @param x       the x of the bridge
 * @param y       the y of the bridge
 * @param z       the z of the bridge
 * @param offset  number representing whether to level or sloped and the direction
 * @param overlay do we want to still see the road?
 * @param head    are we drawing bridge head?
 */
static void DrawBridgeTramBits(int x, int y, byte z, int offset, bool overlay, bool head)
{
	static const SpriteID tram_offsets[2][6] = { { 107, 108, 109, 110, 111, 112 }, { 4, 5, 15, 16, 17, 18 } };
	static const SpriteID back_offsets[6]    =   {  95,  96,  99, 102, 100, 101 };
	static const SpriteID front_offsets[6]   =   {  97,  98, 103, 106, 104, 105 };

	static const uint size_x[6] = {  1, 16, 16,  1, 16,  1 };
	static const uint size_y[6] = { 16,  1,  1, 16,  1, 16 };
	static const uint front_bb_offset_x[6] = { 15,  0,  0, 15,  0, 15 };
	static const uint front_bb_offset_y[6] = {  0, 15, 15,  0, 15,  0 };

	/* The sprites under the vehicles are drawn as SpriteCombine. StartSpriteCombine() has already been called
	 * The bounding boxes here are the same as for bridge front/roof */
	if (head || !IsInvisibilitySet(TO_BRIDGES)) {
		AddSortableSpriteToDraw(SPR_TRAMWAY_BASE + tram_offsets[overlay][offset], PAL_NONE,
			x, y, size_x[offset], size_y[offset], 0x28, z,
			!head && IsTransparencySet(TO_BRIDGES));
	}

	/* Do not draw catenary if it is set invisible */
	if (!IsInvisibilitySet(TO_CATENARY)) {
		AddSortableSpriteToDraw(SPR_TRAMWAY_BASE + back_offsets[offset], PAL_NONE,
			x, y, size_x[offset], size_y[offset], 0x28, z,
			IsTransparencySet(TO_CATENARY));
	}

	/* Start a new SpriteCombine for the front part */
	EndSpriteCombine();
	StartSpriteCombine();

	/* For sloped sprites the bounding box needs to be higher, as the pylons stop on a higher point */
	if (!IsInvisibilitySet(TO_CATENARY)) {
		AddSortableSpriteToDraw(SPR_TRAMWAY_BASE + front_offsets[offset], PAL_NONE,
			x, y, size_x[offset] + front_bb_offset_x[offset], size_y[offset] + front_bb_offset_y[offset], 0x28, z,
			IsTransparencySet(TO_CATENARY), front_bb_offset_x[offset], front_bb_offset_y[offset]);
	}
}

/**
 * Draws a tunnel of bridge tile.
 * For tunnels, this is rather simple, as you only needa draw the entrance.
 * Bridges are a bit more complex. base_offset is where the sprite selection comes into play
 * and it works a bit like a bitmask.<p> For bridge heads:
 * @param ti TileInfo of the structure to draw
 * <ul><li>Bit 0: direction</li>
 * <li>Bit 1: northern or southern heads</li>
 * <li>Bit 2: Set if the bridge head is sloped</li>
 * <li>Bit 3 and more: Railtype Specific subset</li>
 * </ul>
 * Please note that in this code, "roads" are treated as railtype 1, whilst the real railtypes are 0, 2 and 3
 */
static void DrawTile_TunnelBridge(TileInfo *ti)
{
	SpriteID image;
	TransportType transport_type = GetTunnelBridgeTransportType(ti->tile);
	DiagDirection tunnelbridge_direction = GetTunnelBridgeDirection(ti->tile);

	if (IsTunnel(ti->tile)) {
		/* Front view of tunnel bounding boxes:
		 *
		 *   122223  <- BB_Z_SEPARATOR
		 *   1    3
		 *   1    3                1,3 = empty helper BB
		 *   1    3                  2 = SpriteCombine of tunnel-roof and catenary (tram & elrail)
		 *
		 */

		static const int _tunnel_BB[4][12] = {
			/*  tunnnel-roof  |  Z-separator  | tram-catenary
			 * w  h  bb_x bb_y| x   y   w   h |bb_x bb_y w h */
			{  1,  0, -15, -14,  0, 15, 16,  1, 0, 1, 16, 15 }, // NE
			{  0,  1, -14, -15, 15,  0,  1, 16, 1, 0, 15, 16 }, // SE
			{  1,  0, -15, -14,  0, 15, 16,  1, 0, 1, 16, 15 }, // SW
			{  0,  1, -14, -15, 15,  0,  1, 16, 1, 0, 15, 16 }, // NW
		};
		const int *BB_data = _tunnel_BB[tunnelbridge_direction];

		bool catenary = false;

		if (transport_type == TRANSPORT_RAIL) {
			image = GetRailTypeInfo(GetRailType(ti->tile))->base_sprites.tunnel;
		} else {
			image = SPR_TUNNEL_ENTRY_REAR_ROAD;
		}

		if (HasTunnelBridgeSnowOrDesert(ti->tile)) image += 32;

		image += tunnelbridge_direction * 2;
		DrawGroundSprite(image, PAL_NONE);

		/* PBS debugging, draw reserved tracks darker */
		if (_game_mode != GM_MENU && _settings_client.gui.show_track_reservation && (transport_type == TRANSPORT_RAIL && GetTunnelBridgeReservation(ti->tile))) {
			const RailtypeInfo *rti = GetRailTypeInfo(GetRailType(ti->tile));
			DrawGroundSprite(DiagDirToAxis(tunnelbridge_direction) == AXIS_X ? rti->base_sprites.single_y : rti->base_sprites.single_x, PALETTE_CRASH);
		}

		if (transport_type == TRANSPORT_ROAD) {
			RoadTypes rts = GetRoadTypes(ti->tile);

			if (HasBit(rts, ROADTYPE_TRAM)) {
				static const SpriteID tunnel_sprites[2][4] = { { 28, 78, 79, 27 }, {  5, 76, 77,  4 } };

				DrawGroundSprite(SPR_TRAMWAY_BASE + tunnel_sprites[rts - ROADTYPES_TRAM][tunnelbridge_direction], PAL_NONE);

				/* Do not draw wires if they are invisible */
				if (!IsInvisibilitySet(TO_CATENARY)) {
					catenary = true;
					StartSpriteCombine();
					AddSortableSpriteToDraw(SPR_TRAMWAY_TUNNEL_WIRES + tunnelbridge_direction, PAL_NONE, ti->x, ti->y, BB_data[10], BB_data[11], TILE_HEIGHT, ti->z, IsTransparencySet(TO_CATENARY), BB_data[8], BB_data[9], BB_Z_SEPARATOR);
				}
			}
		} else if (HasCatenaryDrawn(GetRailType(ti->tile))) {
			/* Maybe draw pylons on the entry side */
			DrawCatenary(ti);

			catenary = true;
			StartSpriteCombine();
			/* Draw wire above the ramp */
			DrawCatenaryOnTunnel(ti);
		}

		AddSortableSpriteToDraw(image + 1, PAL_NONE, ti->x + TILE_SIZE - 1, ti->y + TILE_SIZE - 1, BB_data[0], BB_data[1], TILE_HEIGHT, ti->z, false, BB_data[2], BB_data[3], BB_Z_SEPARATOR);

		if (catenary) EndSpriteCombine();

		/* Add helper BB for sprite sorting, that separate the tunnel from things beside of it */
		AddSortableSpriteToDraw(SPR_EMPTY_BOUNDING_BOX, PAL_NONE, ti->x             , ti->y             , BB_data[6], BB_data[7], TILE_HEIGHT, ti->z);
		AddSortableSpriteToDraw(SPR_EMPTY_BOUNDING_BOX, PAL_NONE, ti->x + BB_data[4], ti->y + BB_data[5], BB_data[6], BB_data[7], TILE_HEIGHT, ti->z);

		DrawBridgeMiddle(ti);
	} else { // IsBridge(ti->tile)
		const PalSpriteID *psid;
		int base_offset;
		bool ice = HasTunnelBridgeSnowOrDesert(ti->tile);

		if (transport_type == TRANSPORT_RAIL) {
			base_offset = GetRailTypeInfo(GetRailType(ti->tile))->bridge_offset;
			assert(base_offset != 8); // This one is used for roads
		} else {
			base_offset = 8;
		}

		/* as the lower 3 bits are used for other stuff, make sure they are clear */
		assert( (base_offset & 0x07) == 0x00);

		DrawFoundation(ti, GetBridgeFoundation(ti->tileh, DiagDirToAxis(tunnelbridge_direction)));

		/* HACK Wizardry to convert the bridge ramp direction into a sprite offset */
		base_offset += (6 - tunnelbridge_direction) % 4;

		if (ti->tileh == SLOPE_FLAT) base_offset += 4; // sloped bridge head

		/* Table number BRIDGE_PIECE_HEAD always refers to the bridge heads for any bridge type */
		if (transport_type != TRANSPORT_WATER) {
			psid = &GetBridgeSpriteTable(GetBridgeType(ti->tile), BRIDGE_PIECE_HEAD)[base_offset];
		} else {
			psid = _aqueduct_sprites + base_offset;
		}

		if (!ice) {
			DrawClearLandTile(ti, 3);
		} else {
			DrawGroundSprite(SPR_FLAT_SNOWY_TILE + _tileh_to_sprite[ti->tileh], PAL_NONE);
		}

		/* draw ramp */

		/* Draw Trambits as SpriteCombine */
		if (transport_type == TRANSPORT_ROAD) StartSpriteCombine();

		/* HACK set the height of the BB of a sloped ramp to 1 so a vehicle on
		 * it doesn't disappear behind it
		 */
		/* Bridge heads are drawn solid no matter how invisibility/transparency is set */
		AddSortableSpriteToDraw(psid->sprite, psid->pal, ti->x, ti->y, 16, 16, ti->tileh == SLOPE_FLAT ? 0 : 8, ti->z);

		if (_settings_client.gui.show_track_reservation && transport_type == TRANSPORT_RAIL && GetTunnelBridgeReservation(ti->tile)) {
			const RailtypeInfo *rti = GetRailTypeInfo(GetRailType(ti->tile));
			if (HasBridgeFlatRamp(ti->tileh, DiagDirToAxis(tunnelbridge_direction))) {
				AddSortableSpriteToDraw(DiagDirToAxis(tunnelbridge_direction) == AXIS_X ? rti->base_sprites.single_y : rti->base_sprites.single_x, PALETTE_CRASH, ti->x, ti->y, 16, 16, 0, ti->z + 8);
			} else {
				AddSortableSpriteToDraw(rti->base_sprites.single_sloped + tunnelbridge_direction, PALETTE_CRASH, ti->x, ti->y, 16, 16, 8, ti->z);
			}
		}

		if (transport_type == TRANSPORT_ROAD) {
			RoadTypes rts = GetRoadTypes(ti->tile);

			if (HasBit(rts, ROADTYPE_TRAM)) {
				uint offset = tunnelbridge_direction;
				uint z = ti->z;
				if (ti->tileh != SLOPE_FLAT) {
					offset = (offset + 1) & 1;
					z += TILE_HEIGHT;
				} else {
					offset += 2;
				}
				/* DrawBridgeTramBits() calls EndSpriteCombine() and StartSpriteCombine() */
				DrawBridgeTramBits(ti->x, ti->y, z, offset, HasBit(rts, ROADTYPE_ROAD), true);
			}
			EndSpriteCombine();
		} else if (transport_type == TRANSPORT_RAIL) {
			if (HasCatenaryDrawn(GetRailType(ti->tile))) {
				DrawCatenary(ti);
			}
		}

		DrawBridgeMiddle(ti);
	}
}


/** Compute bridge piece. Computes the bridge piece to display depending on the position inside the bridge.
 * bridges pieces sequence (middle parts).
 * Note that it is not covering the bridge heads, which are always referenced by the same sprite table.
 * bridge len 1: BRIDGE_PIECE_NORTH
 * bridge len 2: BRIDGE_PIECE_NORTH  BRIDGE_PIECE_SOUTH
 * bridge len 3: BRIDGE_PIECE_NORTH  BRIDGE_PIECE_MIDDLE_ODD   BRIDGE_PIECE_SOUTH
 * bridge len 4: BRIDGE_PIECE_NORTH  BRIDGE_PIECE_INNER_NORTH  BRIDGE_PIECE_INNER_SOUTH  BRIDGE_PIECE_SOUTH
 * bridge len 5: BRIDGE_PIECE_NORTH  BRIDGE_PIECE_INNER_NORTH  BRIDGE_PIECE_MIDDLE_EVEN  BRIDGE_PIECE_INNER_SOUTH  BRIDGE_PIECE_SOUTH
 * bridge len 6: BRIDGE_PIECE_NORTH  BRIDGE_PIECE_INNER_NORTH  BRIDGE_PIECE_INNER_SOUTH  BRIDGE_PIECE_INNER_NORTH  BRIDGE_PIECE_INNER_SOUTH  BRIDGE_PIECE_SOUTH
 * bridge len 7: BRIDGE_PIECE_NORTH  BRIDGE_PIECE_INNER_NORTH  BRIDGE_PIECE_INNER_SOUTH  BRIDGE_PIECE_MIDDLE_ODD   BRIDGE_PIECE_INNER_NORTH  BRIDGE_PIECE_INNER_SOUTH  BRIDGE_PIECE_SOUTH
 * #0 - always as first, #1 - always as last (if len>1)
 * #2,#3 are to pair in order
 * for odd bridges: #5 is going in the bridge middle if on even position, #4 on odd (counting from 0)
 * @param north Northernmost tile of bridge
 * @param south Southernmost tile of bridge
 * @return Index of bridge piece
 */
static BridgePieces CalcBridgePiece(uint north, uint south)
{
	if (north == 1) {
		return BRIDGE_PIECE_NORTH;
	} else if (south == 1) {
		return BRIDGE_PIECE_SOUTH;
	} else if (north < south) {
		return north & 1 ? BRIDGE_PIECE_INNER_SOUTH : BRIDGE_PIECE_INNER_NORTH;
	} else if (north > south) {
		return south & 1 ? BRIDGE_PIECE_INNER_NORTH : BRIDGE_PIECE_INNER_SOUTH;
	} else {
		return north & 1 ? BRIDGE_PIECE_MIDDLE_EVEN : BRIDGE_PIECE_MIDDLE_ODD;
	}
}


void DrawBridgeMiddle(const TileInfo *ti)
{
	/* Sectional view of bridge bounding boxes:
	 *
	 *  1           2                                1,2 = SpriteCombine of Bridge front/(back&floor) and TramCatenary
	 *  1           2                                  3 = empty helper BB
	 *  1     7     2                                4,5 = pillars under higher bridges
	 *  1 6 88888 6 2                                  6 = elrail-pylons
	 *  1 6 88888 6 2                                  7 = elrail-wire
	 *  1 6 88888 6 2  <- TILE_HEIGHT                  8 = rail-vehicle on bridge
	 *  3333333333333  <- BB_Z_SEPARATOR
	 *                 <- unused
	 *    4       5    <- BB_HEIGHT_UNDER_BRIDGE
	 *    4       5
	 *    4       5
	 *
	 */

	/* Z position of the bridge sprites relative to bridge height (downwards) */
	static const int BRIDGE_Z_START = 3;

	if (!IsBridgeAbove(ti->tile)) return;

	TileIndex rampnorth = GetNorthernBridgeEnd(ti->tile);
	TileIndex rampsouth = GetSouthernBridgeEnd(ti->tile);
	TransportType transport_type = GetTunnelBridgeTransportType(rampsouth);

	Axis axis = GetBridgeAxis(ti->tile);
	BridgePieces piece = CalcBridgePiece(
		GetTunnelBridgeLength(ti->tile, rampnorth) + 1,
		GetTunnelBridgeLength(ti->tile, rampsouth) + 1
	);

	const PalSpriteID *psid;
	bool drawfarpillar;
	if (transport_type != TRANSPORT_WATER) {
		BridgeType type =  GetBridgeType(rampsouth);
		drawfarpillar = !HasBit(GetBridgeSpec(type)->flags, 0);

		uint base_offset;
		if (transport_type == TRANSPORT_RAIL) {
			base_offset = GetRailTypeInfo(GetRailType(rampsouth))->bridge_offset;
		} else {
			base_offset = 8;
		}

		psid = base_offset + GetBridgeSpriteTable(type, piece);
	} else {
		drawfarpillar = true;
		psid = _aqueduct_sprites;
	}

	if (axis != AXIS_X) psid += 4;

	int x = ti->x;
	int y = ti->y;
	uint bridge_z = GetBridgeHeight(rampsouth);
	uint z = bridge_z - BRIDGE_Z_START;

	/* Add a bounding box, that separates the bridge from things below it. */
	AddSortableSpriteToDraw(SPR_EMPTY_BOUNDING_BOX, PAL_NONE, x, y, 16, 16, 1, bridge_z - TILE_HEIGHT + BB_Z_SEPARATOR);

	/* Draw Trambits as SpriteCombine */
	if (transport_type == TRANSPORT_ROAD) StartSpriteCombine();

	/* Draw floor and far part of bridge*/
	if (!IsInvisibilitySet(TO_BRIDGES)) {
		if (axis == AXIS_X) {
			AddSortableSpriteToDraw(psid->sprite, psid->pal, x, y, 16, 1, 0x28, z, IsTransparencySet(TO_BRIDGES), 0, 0, BRIDGE_Z_START);
		} else {
			AddSortableSpriteToDraw(psid->sprite, psid->pal, x, y, 1, 16, 0x28, z, IsTransparencySet(TO_BRIDGES), 0, 0, BRIDGE_Z_START);
		}
	}

	psid++;

	if (transport_type == TRANSPORT_ROAD) {
		RoadTypes rts = GetRoadTypes(rampsouth);

		if (HasBit(rts, ROADTYPE_TRAM)) {
			/* DrawBridgeTramBits() calls EndSpriteCombine() and StartSpriteCombine() */
			DrawBridgeTramBits(x, y, bridge_z, axis ^ 1, HasBit(rts, ROADTYPE_ROAD), false);
		} else {
			EndSpriteCombine();
			StartSpriteCombine();
		}
	} else if (transport_type == TRANSPORT_RAIL) {
		if (HasCatenaryDrawn(GetRailType(rampsouth))) {
			DrawCatenaryOnBridge(ti);
		}
	}

	/* draw roof, the component of the bridge which is logically between the vehicle and the camera */
	if (!IsInvisibilitySet(TO_BRIDGES)) {
		if (axis == AXIS_X) {
			y += 12;
			if (psid->sprite & SPRITE_MASK) AddSortableSpriteToDraw(psid->sprite, psid->pal, x, y, 16, 4, 0x28, z, IsTransparencySet(TO_BRIDGES), 0, 3, BRIDGE_Z_START);
		} else {
			x += 12;
			if (psid->sprite & SPRITE_MASK) AddSortableSpriteToDraw(psid->sprite, psid->pal, x, y, 4, 16, 0x28, z, IsTransparencySet(TO_BRIDGES), 3, 0, BRIDGE_Z_START);
		}
	}

	/* Draw TramFront as SpriteCombine */
	if (transport_type == TRANSPORT_ROAD) EndSpriteCombine();

	/* Do not draw anything more if bridges are invisible */
	if (IsInvisibilitySet(TO_BRIDGES)) return;

	psid++;
	if (ti->z + 5 == z) {
		/* draw poles below for small bridges */
		if (psid->sprite != 0) {
			SpriteID image = psid->sprite;
			SpriteID pal   = psid->pal;
			if (IsTransparencySet(TO_BRIDGES)) {
				SetBit(image, PALETTE_MODIFIER_TRANSPARENT);
				pal = PALETTE_TO_TRANSPARENT;
			}

			DrawGroundSpriteAt(image, pal, x, y, z);
		}
	} else if (_settings_client.gui.bridge_pillars) {
		/* draw pillars below for high bridges */
		DrawBridgePillars(psid, ti, axis, drawfarpillar, x, y, z);
	}
}


static uint GetSlopeZ_TunnelBridge(TileIndex tile, uint x, uint y)
{
	uint z;
	Slope tileh = GetTileSlope(tile, &z);

	x &= 0xF;
	y &= 0xF;

	if (IsTunnel(tile)) {
		uint pos = (DiagDirToAxis(GetTunnelBridgeDirection(tile)) == AXIS_X ? y : x);

		/* In the tunnel entrance? */
		if (5 <= pos && pos <= 10) return z;
	} else { // IsBridge(tile)
		DiagDirection dir = GetTunnelBridgeDirection(tile);
		uint pos = (DiagDirToAxis(dir) == AXIS_X ? y : x);

		z += ApplyFoundationToSlope(GetBridgeFoundation(tileh, DiagDirToAxis(dir)), &tileh);

		/* On the bridge ramp? */
		if (5 <= pos && pos <= 10) {
			uint delta;

			if (tileh != SLOPE_FLAT) return z + TILE_HEIGHT;

			switch (dir) {
				default: NOT_REACHED();
				case DIAGDIR_NE: delta = (TILE_SIZE - 1 - x) / 2; break;
				case DIAGDIR_SE: delta = y / 2; break;
				case DIAGDIR_SW: delta = x / 2; break;
				case DIAGDIR_NW: delta = (TILE_SIZE - 1 - y) / 2; break;
			}
			return z + 1 + delta;
		}
	}

	return z + GetPartialZ(x, y, tileh);
}

static Foundation GetFoundation_TunnelBridge(TileIndex tile, Slope tileh)
{
	return IsTunnel(tile) ? FOUNDATION_NONE : GetBridgeFoundation(tileh, DiagDirToAxis(GetTunnelBridgeDirection(tile)));
}


static void GetAcceptedCargo_TunnelBridge(TileIndex tile, AcceptedCargo ac)
{
	/* not used */
}

static void GetTileDesc_TunnelBridge(TileIndex tile, TileDesc *td)
{
	TransportType tt = GetTunnelBridgeTransportType(tile);

	if (IsTunnel(tile)) {
		td->str = (tt == TRANSPORT_RAIL) ? STR_TUNNEL_DESCRIPTION_RAILROAD : STR_TUNNEL_DESCRIPTION_ROAD;
	} else { // IsBridge(tile)
		td->str = (tt == TRANSPORT_WATER) ? STR_BRIDGE_DESCRIPTION_AQUEDUCT : GetBridgeSpec(GetBridgeType(tile))->transport_name[tt];
	}
	td->owner[0] = GetTileOwner(tile);

	Owner road_owner = INVALID_OWNER;
	Owner tram_owner = INVALID_OWNER;
	RoadTypes rts = GetRoadTypes(tile);
	if (HasBit(rts, ROADTYPE_ROAD)) road_owner = GetRoadOwner(tile, ROADTYPE_ROAD);
	if (HasBit(rts, ROADTYPE_TRAM)) tram_owner = GetRoadOwner(tile, ROADTYPE_TRAM);

	/* Is there a mix of owners? */
	if ((tram_owner != INVALID_OWNER && tram_owner != td->owner[0]) ||
			(road_owner != INVALID_OWNER && road_owner != td->owner[0])) {
		uint i = 1;
		if (road_owner != INVALID_OWNER) {
			td->owner_type[i] = STR_LAND_AREA_INFORMATION_ROAD_OWNER;
			td->owner[i] = road_owner;
			i++;
		}
		if (tram_owner != INVALID_OWNER) {
			td->owner_type[i] = STR_LAND_AREA_INFORMATION_TRAM_OWNER;
			td->owner[i] = tram_owner;
		}
	}
}


static void AnimateTile_TunnelBridge(TileIndex tile)
{
	/* not used */
}

static void TileLoop_TunnelBridge(TileIndex tile)
{
	bool snow_or_desert = HasTunnelBridgeSnowOrDesert(tile);
	switch (_settings_game.game_creation.landscape) {
		case LT_ARCTIC:
			if (snow_or_desert != (GetTileZ(tile) > GetSnowLine())) {
				SetTunnelBridgeSnowOrDesert(tile, !snow_or_desert);
				MarkTileDirtyByTile(tile);
			}
			break;

		case LT_TROPIC:
			if (GetTropicZone(tile) == TROPICZONE_DESERT && !snow_or_desert) {
				SetTunnelBridgeSnowOrDesert(tile, true);
				MarkTileDirtyByTile(tile);
			}
			break;

		default:
			break;
	}
}

static bool ClickTile_TunnelBridge(TileIndex tile)
{
	/* not used */
	return false;
}


static TrackStatus GetTileTrackStatus_TunnelBridge(TileIndex tile, TransportType mode, uint sub_mode, DiagDirection side)
{
	TransportType transport_type = GetTunnelBridgeTransportType(tile);
	if (transport_type != mode || (transport_type == TRANSPORT_ROAD && (GetRoadTypes(tile) & sub_mode) == 0)) return 0;

	DiagDirection dir = GetTunnelBridgeDirection(tile);
	if (side != INVALID_DIAGDIR && side != ReverseDiagDir(dir)) return 0;
	return CombineTrackStatus(TrackBitsToTrackdirBits(DiagDirToDiagTrackBits(dir)), TRACKDIR_BIT_NONE);
}

static void ChangeTileOwner_TunnelBridge(TileIndex tile, Owner old_owner, Owner new_owner)
{
	for (RoadType rt = ROADTYPE_ROAD; rt < ROADTYPE_END; rt++) {
		/* Update all roadtypes, no matter if they are present */
		if (GetRoadOwner(tile, rt) == old_owner) {
			SetRoadOwner(tile, rt, new_owner == INVALID_OWNER ? OWNER_NONE : new_owner);
		}
	}

	if (!IsTileOwner(tile, old_owner)) return;

	if (new_owner != INVALID_OWNER) {
		SetTileOwner(tile, new_owner);
	} else {
		if (CmdFailed(DoCommand(tile, 0, 0, DC_EXEC | DC_BANKRUPT, CMD_LANDSCAPE_CLEAR))) {
			/* When clearing the bridge/tunnel failed there are still vehicles on/in
			 * the bridge/tunnel. As all *our* vehicles are already removed, they
			 * must be of another owner. Therefore this can't be rail tunnel/bridge.
			 * In that case we can safely reassign the ownership to OWNER_NONE. */
			assert(GetTunnelBridgeTransportType(tile) != TRANSPORT_RAIL);
			SetTileOwner(tile, OWNER_NONE);
		}
	}
}


static const byte _tunnel_fractcoord_1[4]    = {0x8E, 0x18, 0x81, 0xE8};
static const byte _tunnel_fractcoord_2[4]    = {0x81, 0x98, 0x87, 0x38};
static const byte _tunnel_fractcoord_3[4]    = {0x82, 0x88, 0x86, 0x48};
static const byte _exit_tunnel_track[4]      = {1, 2, 1, 2};

/** Get the trackdir of the exit of a tunnel */
static const Trackdir _road_exit_tunnel_state[DIAGDIR_END] = {
	TRACKDIR_X_SW, TRACKDIR_Y_NW, TRACKDIR_X_NE, TRACKDIR_Y_SE
};
static const byte _road_exit_tunnel_frame[4] = {2, 7, 9, 4};

static const byte _tunnel_fractcoord_4[4]    = {0x52, 0x85, 0x98, 0x29};
static const byte _tunnel_fractcoord_5[4]    = {0x92, 0x89, 0x58, 0x25};
static const byte _tunnel_fractcoord_6[4]    = {0x92, 0x89, 0x56, 0x45};
static const byte _tunnel_fractcoord_7[4]    = {0x52, 0x85, 0x96, 0x49};

static VehicleEnterTileStatus VehicleEnter_TunnelBridge(Vehicle *v, TileIndex tile, int x, int y)
{
	int z = GetSlopeZ(x, y) - v->z_pos;

	if (abs(z) > 2) return VETSB_CANNOT_ENTER;
	const DiagDirection dir = GetTunnelBridgeDirection(tile);

	if (IsTunnel(tile)) {
		byte fc;
		DiagDirection vdir;

		if (v->type == VEH_TRAIN) {
			fc = (x & 0xF) + (y << 4);

			vdir = DirToDiagDir(v->direction);

			if (v->u.rail.track != TRACK_BIT_WORMHOLE && dir == vdir) {
				if (IsFrontEngine(v) && fc == _tunnel_fractcoord_1[dir]) {
					if (!PlayVehicleSound(v, VSE_TUNNEL) && RailVehInfo(v->engine_type)->engclass == 0) {
						SndPlayVehicleFx(SND_05_TRAIN_THROUGH_TUNNEL, v);
					}
					return VETSB_CONTINUE;
				}
				if (fc == _tunnel_fractcoord_2[dir]) {
					v->tile = tile;
					v->u.rail.track = TRACK_BIT_WORMHOLE;
					v->vehstatus |= VS_HIDDEN;
					return VETSB_ENTERED_WORMHOLE;
				}
			}

			if (dir == ReverseDiagDir(vdir) && fc == _tunnel_fractcoord_3[dir] && z == 0) {
				/* We're at the tunnel exit ?? */
				v->tile = tile;
				v->u.rail.track = (TrackBits)_exit_tunnel_track[dir];
				assert(v->u.rail.track);
				v->vehstatus &= ~VS_HIDDEN;
				return VETSB_ENTERED_WORMHOLE;
			}
		} else if (v->type == VEH_ROAD) {
			fc = (x & 0xF) + (y << 4);
			vdir = DirToDiagDir(v->direction);

			/* Enter tunnel? */
			if (v->u.road.state != RVSB_WORMHOLE && dir == vdir) {
				if (fc == _tunnel_fractcoord_4[dir] ||
						fc == _tunnel_fractcoord_5[dir]) {
					v->tile = tile;
					v->u.road.state = RVSB_WORMHOLE;
					v->vehstatus |= VS_HIDDEN;
					return VETSB_ENTERED_WORMHOLE;
				} else {
					return VETSB_CONTINUE;
				}
			}

			if (dir == ReverseDiagDir(vdir) && (
						/* We're at the tunnel exit ?? */
						fc == _tunnel_fractcoord_6[dir] ||
						fc == _tunnel_fractcoord_7[dir]
					) &&
					z == 0) {
				v->tile = tile;
				v->u.road.state = _road_exit_tunnel_state[dir];
				v->u.road.frame = _road_exit_tunnel_frame[dir];
				v->vehstatus &= ~VS_HIDDEN;
				return VETSB_ENTERED_WORMHOLE;
			}
		}
	} else { // IsBridge(tile)

		if (v->IsPrimaryVehicle() && v->type != VEH_SHIP) {
			/* modify speed of vehicle */
			uint16 spd = GetBridgeSpec(GetBridgeType(tile))->speed;

			if (v->type == VEH_ROAD) spd *= 2;
			if (v->cur_speed > spd) v->cur_speed = spd;
		}

		if (DirToDiagDir(v->direction) == dir) {
			switch (dir) {
				default: NOT_REACHED();
				case DIAGDIR_NE: if ((x & 0xF) != 0)             return VETSB_CONTINUE; break;
				case DIAGDIR_SE: if ((y & 0xF) != TILE_SIZE - 1) return VETSB_CONTINUE; break;
				case DIAGDIR_SW: if ((x & 0xF) != TILE_SIZE - 1) return VETSB_CONTINUE; break;
				case DIAGDIR_NW: if ((y & 0xF) != 0)             return VETSB_CONTINUE; break;
			}
			switch (v->type) {
				case VEH_TRAIN:
					v->u.rail.track = TRACK_BIT_WORMHOLE;
					ClrBit(v->u.rail.flags, VRF_GOINGUP);
					ClrBit(v->u.rail.flags, VRF_GOINGDOWN);
					break;

				case VEH_ROAD:
					v->u.road.state = RVSB_WORMHOLE;
					break;

				case VEH_SHIP:
					v->u.ship.state = TRACK_BIT_WORMHOLE;
					break;

				default: NOT_REACHED();
			}
			return VETSB_ENTERED_WORMHOLE;
		} else if (DirToDiagDir(v->direction) == ReverseDiagDir(dir)) {
			v->tile = tile;
			switch (v->type) {
				case VEH_TRAIN:
					if (v->u.rail.track == TRACK_BIT_WORMHOLE) {
						v->u.rail.track = (DiagDirToAxis(dir) == AXIS_X ? TRACK_BIT_X : TRACK_BIT_Y);
						return VETSB_ENTERED_WORMHOLE;
					}
					break;

				case VEH_ROAD:
					if (v->u.road.state == RVSB_WORMHOLE) {
						v->u.road.state = _road_exit_tunnel_state[dir];
						v->u.road.frame = 0;
						return VETSB_ENTERED_WORMHOLE;
					}
					break;

				case VEH_SHIP:
					if (v->u.ship.state == TRACK_BIT_WORMHOLE) {
						v->u.ship.state = (DiagDirToAxis(dir) == AXIS_X ? TRACK_BIT_X : TRACK_BIT_Y);
						return VETSB_ENTERED_WORMHOLE;
					}
					break;

				default: NOT_REACHED();
			}
		}
	}
	return VETSB_CONTINUE;
}

static CommandCost TerraformTile_TunnelBridge(TileIndex tile, DoCommandFlag flags, uint z_new, Slope tileh_new)
{
	if (_settings_game.construction.build_on_slopes && AutoslopeEnabled() && IsBridge(tile) && GetTunnelBridgeTransportType(tile) != TRANSPORT_WATER) {
		DiagDirection direction = GetTunnelBridgeDirection(tile);
		Axis axis = DiagDirToAxis(direction);
		CommandCost res;
		uint z_old;
		Slope tileh_old = GetTileSlope(tile, &z_old);

		/* Check if new slope is valid for bridges in general (so we can safely call GetBridgeFoundation()) */
		if ((direction == DIAGDIR_NW) || (direction == DIAGDIR_NE)) {
			CheckBridgeSlopeSouth(axis, &tileh_old, &z_old);
			res = CheckBridgeSlopeSouth(axis, &tileh_new, &z_new);
		} else {
			CheckBridgeSlopeNorth(axis, &tileh_old, &z_old);
			res = CheckBridgeSlopeNorth(axis, &tileh_new, &z_new);
		}

		/* Surface slope is valid and remains unchanged? */
		if (!CmdFailed(res) && (z_old == z_new) && (tileh_old == tileh_new)) return CommandCost(EXPENSES_CONSTRUCTION, _price.terraform);
	}

	return DoCommand(tile, 0, 0, flags, CMD_LANDSCAPE_CLEAR);
}

extern const TileTypeProcs _tile_type_tunnelbridge_procs = {
	DrawTile_TunnelBridge,           // draw_tile_proc
	GetSlopeZ_TunnelBridge,          // get_slope_z_proc
	ClearTile_TunnelBridge,          // clear_tile_proc
	GetAcceptedCargo_TunnelBridge,   // get_accepted_cargo_proc
	GetTileDesc_TunnelBridge,        // get_tile_desc_proc
	GetTileTrackStatus_TunnelBridge, // get_tile_track_status_proc
	ClickTile_TunnelBridge,          // click_tile_proc
	AnimateTile_TunnelBridge,        // animate_tile_proc
	TileLoop_TunnelBridge,           // tile_loop_clear
	ChangeTileOwner_TunnelBridge,    // change_tile_owner_clear
	NULL,                            // get_produced_cargo_proc
	VehicleEnter_TunnelBridge,       // vehicle_enter_tile_proc
	GetFoundation_TunnelBridge,      // get_foundation_proc
	TerraformTile_TunnelBridge,      // terraform_tile_proc
};