re-implented trailing calculations of train

pom.xml

@@ -4,7 +4,7 @@
 	<modelVersion>4.0.0</modelVersion>
 	<groupId>de.srsoftware</groupId>
 	<artifactId>web4rail</artifactId>
-	<version>0.9.20</version>
+	<version>0.10.1</version>
 	<name>Web4Rail</name>
 	<packaging>jar</packaging>
 	<description>Java Model Railway Control</description>

resources/translations/Application.de.translation

@@ -32,6 +32,7 @@ Emergency : Notfall
 FinishRoute : Route abschließen
 FreeStartBlock : Start-Block freigeben
 Hardware settings : Hardware-Einstellungen
+Height : Höhe
 Help : Hilfe
 inverted : invertiert
 learn : lernen
@@ -103,4 +104,5 @@ Was not able to assign {} to {}! : Konnte {} nicht an {} zuweisen!
 Was not able to lock {} : Konnte {} nicht reservieren
 Was not able to set all signals! : Konnte nicht alle Signale stellen!
 Was not able to set all turnouts! : Konnte nicht alle Weichen stellen!
-WEST : Westen
+WEST : Westen
+Width : Breite

src/main/java/de/srsoftware/web4rail/BaseClass.java

@@ -0,0 +1,11 @@
+package de.srsoftware.web4rail;
+
+public class BaseClass implements Constants{
+	public static boolean isNull(Object o) {
+		return o==null;
+	}
+
+	public static boolean isSet(Object o) {
+		return o != null;
+	}
+}

src/main/java/de/srsoftware/web4rail/Plan.java

@@ -237,7 +237,7 @@ public class Plan implements Constants{
 	private String analyze() {
 		Vector<Route> routes = new Vector<Route>();
 		for (Block block : blocks) {
-			for (Connector con : block.startPoints()) routes.addAll(follow(new Route().start(block,con.from.inverse()),con));
+			for (Connector con : block.startPoints()) routes.addAll(follow(new Route().begin(block,con.from.inverse()),con));
 		}
 		this.routes.clear();
 		for (Tile tile : tiles.values()) tile.routes().clear();
@@ -586,7 +586,7 @@ public class Plan implements Constants{
 	private void remove(Tile tile) {
 		removeTile(tile.x,tile.y);
 		if (tile instanceof Block) blocks.remove(tile);
-		for (int i=1; i<tile.len(); i++) removeTile(tile.x+i, tile.y); // remove shadow tiles
+		for (int i=1; i<tile.width(); i++) removeTile(tile.x+i, tile.y); // remove shadow tiles
 		for (int i=1; i<tile.height(); i++) removeTile(tile.x, tile.y+i); // remove shadow tiles
 		if (tile != null) stream("remove "+tile.id());
 	}
@@ -649,7 +649,7 @@ public class Plan implements Constants{
 	public void set(int x,int y,Tile tile) throws IOException {
 		if (tile == null) return;
 		if (tile instanceof Block) blocks.add((Block) tile);
-		for (int i=1; i<tile.len(); i++) set(x+i,y,new Shadow(tile));
+		for (int i=1; i<tile.width(); i++) set(x+i,y,new Shadow(tile));
 		for (int i=1; i<tile.height(); i++) set(x,y+i,new Shadow(tile));
 		setIntern(x,y,tile);
 		place(tile);		

src/main/java/de/srsoftware/web4rail/Route.java

@@ -4,7 +4,6 @@ import java.io.BufferedWriter;
 import java.io.FileInputStream;
 import java.io.FileWriter;
 import java.io.IOException;
-import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.List;
@@ -26,7 +25,6 @@ import de.srsoftware.web4rail.actions.Action.Context;
 import de.srsoftware.web4rail.actions.ActionList;
 import de.srsoftware.web4rail.actions.ActivateRoute;
 import de.srsoftware.web4rail.actions.FinishRoute;
-import de.srsoftware.web4rail.actions.FreePreviousBlocks;
 import de.srsoftware.web4rail.actions.SetSignalsToStop;
 import de.srsoftware.web4rail.actions.SetSpeed;
 import de.srsoftware.web4rail.conditions.Condition;
@@ -36,6 +34,7 @@ import de.srsoftware.web4rail.tags.Checkbox;
 import de.srsoftware.web4rail.tags.Fieldset;
 import de.srsoftware.web4rail.tags.Form;
 import de.srsoftware.web4rail.tags.Input;
+import de.srsoftware.web4rail.tags.Label;
 import de.srsoftware.web4rail.tiles.Block;
 import de.srsoftware.web4rail.tiles.Contact;
 import de.srsoftware.web4rail.tiles.Shadow;
@@ -49,7 +48,7 @@ import de.srsoftware.web4rail.tiles.Turnout.State;
  * @author Stephan Richter, SRSoftware
  *
  */
-public class Route implements Constants{
+public class Route extends BaseClass{
 	private static final Logger LOG = LoggerFactory.getLogger(Route.class);
 	static final String NAME = "name";
 	static final String PATH = "path";
@@ -88,14 +87,14 @@ public class Route implements Constants{
 	 */
 	public static Object action(HashMap<String, String> params,Plan plan) throws IOException {
 		Route route = plan.route(Integer.parseInt(params.get(ID)));
-		if (route == null) return t("Unknown route: {}",params.get(ID));
+		if (isNull(route)) return t("Unknown route: {}",params.get(ID));
 		switch (params.get(ACTION)) {
 			case ACTION_DROP:
 				String message = plan.remove(route);
 				String tileId = params.get(Tile.class.getSimpleName());
-				if (tileId != null) {
+				if (isSet(tileId)) {
 					Tile tile = plan.get(tileId, false);
-					if (tile != null) {
+					if (isSet(tile)) {
 						plan.stream(message);
 						return tile.propMenu();
 					}
@@ -113,7 +112,7 @@ public class Route implements Constants{
 
 	private Object dropCodition(HashMap<String, String> params) {
 		String condId = params.get(REALM_CONDITION);
-		if (condId != null) {
+		if (isSet(condId)) {
 			int cid = Integer.parseInt(condId);
 			for (Condition condition : conditions) {
 				if (condition.id() == cid) {
@@ -130,12 +129,7 @@ public class Route implements Constants{
 	 * @throws IOException 
 	 */
 	public void activate() throws IOException {
-		for (Tile tile : path) {
+		// TODO
-			if (!(tile instanceof Block)) tile.trainHead(train);
-		}
-		train.heading(endDirection.inverse());
-		endBlock.trainHead(train);
-		startBlock.trailingTrain(train);
 	}
 	
 	/**
@@ -167,7 +161,7 @@ public class Route implements Constants{
 	 */
 	public void add(String trigger, Action action) {
 		ActionList actions = triggers.get(trigger);
-		if (actions == null) {
+		if (isNull(actions)) {
 			actions = new ActionList();
 			triggers.put(trigger, actions);
 		}
@@ -224,7 +218,7 @@ public class Route implements Constants{
 			for (Contact c : contacts) {
 				Tag link = Plan.addLink(c,c.toString(),list);
 				ActionList actions = triggers.get(c.trigger());
-				if (actions == null) {
+				if (isNull(actions)) {
 					actions = new ActionList();
 					triggers.put(c.trigger(), actions);
 				}
@@ -240,9 +234,7 @@ public class Route implements Constants{
 		new Input(REALM,REALM_ROUTE).hideIn(form);
 		new Input(ID,id()).hideIn(form);
 		if (params.containsKey(CONTEXT)) new Input(CONTEXT,params.get(CONTEXT)).hideIn(form);
-		Tag label = new Tag("label").content(t("name:")+NBSP);
+		new Input(NAME, name()).style("width: 80%").addTo(new Label(t("name:")+NBSP)).addTo(form);
-		new Input(NAME, name()).style("width: 80%").addTo(label);
-		label.addTo(form);
 		new Checkbox(DISABLED, t("disabled"), disabled).addTo(form);
 		
 		new Button(t("Apply"),form).addTo(form).addTo(win);
@@ -281,6 +273,18 @@ public class Route implements Constants{
 		return true;
 	}
 	
+	public Route begin(Block block,Direction from) {
+		// add those fields to clone, too!
+		contacts = new Vector<Contact>();
+		signals = new Vector<Signal>();
+		path = new Vector<Tile>();
+		turnouts = new HashMap<>();
+		startBlock = block;
+		startDirection = from;
+		path.add(block);
+		return this;
+	}
+	
 	protected Route clone() {
 		Route clone = new Route();
 		clone.startBlock = startBlock;
@@ -305,7 +309,6 @@ public class Route implements Constants{
 			Contact lastContact = contacts.lastElement(); 
 			add(lastContact.trigger(), new SetSpeed()); 
 			add(lastContact.trigger(), new FinishRoute());
-			add(lastContact.trigger(), new FreePreviousBlocks());
 		}
 	}
 
@@ -315,13 +318,14 @@ public class Route implements Constants{
 	 * @param trainHead
 	 */
 	public void contact(Contact contact) {
+		traceTrainFrom(contact);
 		LOG.debug("{} on {} activated {}.",train,this,contact);
 		ActionList actions = triggers.get(contact.trigger());
-		if (actions == null) return;
+		if (isNull(actions)) return;
 		Context context = new Context(contact);
 		actions.fire(context);
 	}
-	
+
 	public Vector<Contact> contacts() {
 		return new Vector<>(contacts);
 	}
@@ -335,8 +339,11 @@ public class Route implements Constants{
 	}	
 	
 	public void finish() {
-		reset();
+		setSignals(Signal.STOP);
-		train.block(endBlock, false);
+		for (Tile tile : path) tile.setRoute(null);
+		Tile lastTile = path.lastElement();
+		if (lastTile instanceof Contact) lastTile.set(null);
+		train.set(endBlock);
 		train.heading(endDirection.inverse());
 	}
 	
@@ -344,7 +351,7 @@ public class Route implements Constants{
 		return setupActions.fire(context);
 	}
 	
-	public boolean free() {
+	public boolean isFree() {
 		for (int i=1; i<path.size(); i++) { 
 			if (!path.get(i).isFree()) return false;
 		}
@@ -414,7 +421,7 @@ public class Route implements Constants{
 		if (!setupActions.isEmpty()) json.put(ACTIONS, setupActions.json());
 		
 		String name = name();		
-		if (name != null) json.put(NAME, name);
+		if (isSet(name)) json.put(NAME, name);
 		
 		if (disabled) json.put(DISABLED, true);
 
@@ -428,8 +435,8 @@ public class Route implements Constants{
 		endDirection = Direction.valueOf(json.getString(END_DIRECTION));
 		for (Object tileId : pathIds) {
 			Tile tile = plan.get((String) tileId,false);
-			if (startBlock == null) {
+			if (isNull(startBlock)) {
-				start((Block) tile, startDirection);
+				begin((Block) tile, startDirection);
 			} else if (tile instanceof Block) { // make sure, endDirection is set on last block
 				add(tile,endDirection);
 			} else {
@@ -482,19 +489,25 @@ public class Route implements Constants{
 		for (int i=0; i<arr.length(); i++) {
 			JSONObject json = arr.getJSONObject(i);
 			Condition condition = Condition.create(json.getString(TYPE));
-			if (condition != null) conditions.add(condition.load(json));
+			if (isSet(condition)) conditions.add(condition.load(json));
 		}
 	}
 	
-	public boolean lock() {		
+	public boolean lock() {
-		ArrayList<Tile> lockedTiles = new ArrayList<Tile>();
+		Vector<Tile> alreadyLocked = new Vector<Tile>();
-		try {
+		boolean success = true;
-			for (Tile tile : path) lockedTiles.add(tile.setRoute(this));
+		for (Tile tile : path) {
-		} catch (IllegalStateException e) {
+			try {
-			for (Tile tile: lockedTiles) tile.unlock();
+				tile.setRoute(this);
-			return false;
+			} catch (IllegalStateException e) {
+				success = false;
+				break;
+			}			
 		}
-		return true;
+		if (!success) for (Tile tile :alreadyLocked) {
+			tile.setRoute(null);
+		}
+		return success;
 	}
 	
 	public List<Route> multiply(int size) {
@@ -505,7 +518,7 @@ public class Route implements Constants{
 	
 	public String name() {
 		String name = names.get(id());
-		if (name == null) {			
+		if (isNull(name)) {			
 			name = generateName();
 			name(name);
 		}
@@ -518,7 +531,7 @@ public class Route implements Constants{
 	
 	public Vector<Tile> path() {
 		Vector<Tile> result = new Vector<Tile>();
-		if (path != null) result.addAll(path);
+		if (isSet(path)) result.addAll(path);
 		return result;
 	}
 	
@@ -533,18 +546,9 @@ public class Route implements Constants{
 		return win;
 	}
 	
-	public void reset() {
+	public boolean reset() {
-		new SetSignalsToStop().fire(new Context(this));
+		// TODO
-		for (Tile tile : path) {
+		return false;
-			if (!(tile instanceof Block)) tile.unlock();
-		}
-		if (endBlock.route() == this) endBlock.setRoute(null);
-		if (startBlock.route() == this) startBlock.setRoute(null);
-		if (train != null) {
-			train.heading(startDirection);
-			train.block(startBlock, false);
-			if (train.route == this) train.route = null;
-		}
 	}
 
 	public static void saveAll(Collection<Route> routes, String filename) throws IOException {
@@ -561,14 +565,14 @@ public class Route implements Constants{
 	}
 
 	public void setLast(State state) {
-		if (state == null || state == State.UNDEF) return;
+		if (isNull(state) || state == State.UNDEF) return;
 		Tile lastTile = path.lastElement();
 		if (lastTile instanceof Turnout) addTurnout((Turnout) lastTile,state);
 	}
 	
 	public boolean setSignals(String state) {
 		for (Signal signal : signals) {
-			if (!signal.state(state == null ? Signal.GO : state)) return false;
+			if (!signal.state(isNull(state) ? Signal.GO : state)) return false;
 		}
 		return true;
 	}
@@ -588,18 +592,6 @@ public class Route implements Constants{
 		}
 		return true;
 	}
-	
-	public Route start(Block block,Direction from) {
-		// add those fields to clone, too!
-		contacts = new Vector<Contact>();
-		signals = new Vector<Signal>();
-		path = new Vector<Tile>();
-		turnouts = new HashMap<>();
-		startBlock = block;
-		startDirection = from;
-		path.add(block);
-		return this;
-	}
 
 	public Block startBlock() {
 		return startBlock;
@@ -614,27 +606,35 @@ public class Route implements Constants{
 		return getClass().getSimpleName()+"("+name()+")";
 	}
 	
-	public boolean train(Train train) {
+	private void traceTrainFrom(Tile tile) {
-		if (this.train != null && this.train != train) return false;
+		Vector<Tile> trace = new Vector<Tile>();
-		this.train = train;
+		for (Tile t:path) {
+			trace.add(t);
+			if (t == tile) break;
+		}
+		train.addToTrace(trace);
+	}
+	
+	public boolean train(Train newTrain) {
+		if (isSet(train) && newTrain != train) return false;
+		train = newTrain;
 		return true;
 	}
 	
 	public Route unlock() throws IOException {
-		setSignals(Signal.STOP);
+		// TODO
-		for (Tile tile : path) tile.unlock();
 		return this;
 	}
 
 	public Object update(HashMap<String, String> params,Plan plan) {
 		LOG.debug("update({})",params);
 		String name = params.get(NAME);
-		if (name != null) name(name);
+		if (isSet(name)) name(name);
 		
 		disabled = "on".equals(params.get(DISABLED));
 		
 		Condition condition = Condition.create(params.get(REALM_CONDITION));
-		if (condition != null) {
+		if (isSet(condition)) {
 			conditions.add(condition);
 			return properties(params);
 		}

src/main/java/de/srsoftware/web4rail/actions/Action.java

@@ -14,7 +14,7 @@ import org.slf4j.LoggerFactory;
 import de.keawe.tools.translations.Translation;
 import de.srsoftware.tools.Tag;
 import de.srsoftware.web4rail.Application;
-import de.srsoftware.web4rail.Constants;
+import de.srsoftware.web4rail.BaseClass;
 import de.srsoftware.web4rail.Plan;
 import de.srsoftware.web4rail.Route;
 import de.srsoftware.web4rail.Window;
@@ -23,7 +23,7 @@ import de.srsoftware.web4rail.tags.Label;
 import de.srsoftware.web4rail.tags.Select;
 import de.srsoftware.web4rail.tiles.Contact;
 
-public abstract class Action implements Constants {
+public abstract class Action extends BaseClass {
 	private static final HashMap<Integer,Action> actions = new HashMap<Integer, Action>();
 	public static final Logger LOG = LoggerFactory.getLogger(Action.class);
 	private static final String PREFIX = Action.class.getPackageName();
@@ -50,6 +50,17 @@ public abstract class Action implements Constants {
 			this.route = route;
 			train = route.train;
 		}
+		
+		@Override
+		public String toString() {
+			StringBuffer sb = new StringBuffer(getClass().getSimpleName());
+			sb.append("(");
+			sb.append(t("Train: {}",train));
+			if (isSet(route))   sb.append(", "+t("Route: {}",route));
+			if (isSet(contact)) sb.append(", "+t("Contact: {}",contact));
+			sb.append(")");
+			return sb.toString();
+		}
 	}
 	
 	public Action() {
@@ -59,7 +70,6 @@ public abstract class Action implements Constants {
 	
 	public static Action create(String type) {
 		try {
-			if (type.equals("FreeStartBlock")) type = FreePreviousBlocks.class.getSimpleName();
 			return (Action) Class.forName(PREFIX+"."+type).getDeclaredConstructor().newInstance();
 		} catch (Exception e) {
 			e.printStackTrace();
@@ -92,7 +102,6 @@ public abstract class Action implements Constants {
 			ConditionalAction.class,
 			SetSpeed.class,
 			SetSignalsToStop.class,
-			FreePreviousBlocks.class,
 			FinishRoute.class,
 			TurnTrain.class,
 			StopAuto.class,

src/main/java/de/srsoftware/web4rail/actions/FreePreviousBlocks.java

@@ -1,12 +0,0 @@
-package de.srsoftware.web4rail.actions;
-
-import java.io.IOException;
-
-public class FreePreviousBlocks extends Action {
-
-	@Override
-	public boolean fire(Context context) throws IOException {
-		if (context.train != null) context.train.resetPreviousBlocks();
-		return false;
-	}
-}

src/main/java/de/srsoftware/web4rail/moving/Train.java

@@ -8,6 +8,7 @@ import java.io.IOException;
 import java.util.Collection;
 import java.util.HashMap;
 import java.util.HashSet;
+import java.util.LinkedList;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Random;
@@ -22,7 +23,7 @@ import org.slf4j.LoggerFactory;
 import de.keawe.tools.translations.Translation;
 import de.srsoftware.tools.Tag;
 import de.srsoftware.web4rail.Application;
-import de.srsoftware.web4rail.Constants;
+import de.srsoftware.web4rail.BaseClass;
 import de.srsoftware.web4rail.Plan;
 import de.srsoftware.web4rail.Plan.Direction;
 import de.srsoftware.web4rail.Route;
@@ -36,8 +37,9 @@ import de.srsoftware.web4rail.tags.Input;
 import de.srsoftware.web4rail.tags.Label;
 import de.srsoftware.web4rail.tags.Select;
 import de.srsoftware.web4rail.tiles.Block;
+import de.srsoftware.web4rail.tiles.Tile;
 
-public class Train implements Comparable<Train>,Constants {
+public class Train extends BaseClass implements Comparable<Train> {
 	private static final Logger LOG = LoggerFactory.getLogger(Train.class);
 
 	public static final String HEAD = "train_head";
@@ -71,7 +73,7 @@ public class Train implements Comparable<Train>,Constants {
 
 
 	private Block block = null;
-	private Vector<Block> previousBlocks = new Vector<Block>();
+	LinkedList<Tile> trace = new LinkedList<Tile>();
 		
 	private class Autopilot extends Thread{
 		boolean stop = false;
@@ -81,7 +83,7 @@ public class Train implements Comparable<Train>,Constants {
 			try {
 				stop = false;
 				while (true) {
-					if (route == null) {
+					if (isNull(route)) {
 						Thread.sleep(2000);
 						if (stop) return;
 						Train.this.start();
@@ -107,7 +109,7 @@ public class Train implements Comparable<Train>,Constants {
 	}
 	
 	public Train(Locomotive loco, Integer id) {
-		if (id == null) id = Application.createId();
+		if (isNull(id)) id = Application.createId();
 		this.id = id;
 		add(loco);
 		trains.put(id, this);
@@ -115,7 +117,7 @@ public class Train implements Comparable<Train>,Constants {
 
 	public static Object action(HashMap<String, String> params, Plan plan) throws IOException {
 		String action = params.get(ACTION);
-		if (action == null) return t("No action passed to Train.action!");
+		if (isNull(action)) return t("No action passed to Train.action!");
 		if (!params.containsKey(Train.ID)) {
 			switch (action) {
 				case ACTION_PROPS:
@@ -127,7 +129,7 @@ public class Train implements Comparable<Train>,Constants {
 		}
 		int id = Integer.parseInt(params.get(Train.ID));
 		Train train = trains.get(id);
-		if (train == null) return(t("No train with id {}!",id));
+		if (isNull(train)) return(t("No train with id {}!",id));
 		switch (action) {
 			case ACTION_ADD:
 				return train.addCar(params);
@@ -151,17 +153,18 @@ public class Train implements Comparable<Train>,Constants {
 		return t("Unknown action: {}",params.get(ACTION));
 	}
 
-	private Route chooseRoute(Context context) {		HashSet<Route> routes = block.routes();
+	private Route chooseRoute(Context context) {		
+		HashSet<Route> routes = block.routes();
 		Vector<Route> availableRoutes = new Vector<Route>();
 		for (Route rt : routes) {
 			if (rt == route) continue; // andere Route als zuvor wählen
 			if (rt.path().firstElement() != block) continue; // keine Route wählen, die nicht vom aktuellen Block des Zuges startet
-			if (direction != null && rt.startDirection != direction) { // Route ist entgegen der Startrichtung des Zuges
+			if (isSet(direction) && rt.startDirection != direction) { // Route ist entgegen der Startrichtung des Zuges
 				if (!pushPull || !block.turnAllowed) { // Zug ist kein Wendezug oder Block erlaubt kein Wenden
 					continue;
 				}
 			}
-			if (!rt.free()) { // keine belegten Routen wählen
+			if (!rt.isFree()) { // keine belegten Routen wählen
 				LOG.debug("{} is not free!",rt);
 				continue;
 			}
@@ -180,7 +183,7 @@ public class Train implements Comparable<Train>,Constants {
 
 	public String directedName() {
 		String result = name();
-		if (direction == null) return result;
+		if (isNull(direction)) return result;
 		switch (direction) {
 		case NORTH:
 		case WEST:
@@ -194,9 +197,9 @@ public class Train implements Comparable<Train>,Constants {
 
 	private Object dropCar(HashMap<String, String> params) {
 		String carId = params.get(CAR_ID);
-		if (carId != null) cars.remove(Car.get(carId));
+		if (isSet(carId)) cars.remove(Car.get(carId));
 		String locoId = params.get(LOCO_ID);
-		if (locoId != null) locos.remove(Car.get(locoId));
+		if (isSet(locoId)) locos.remove(Car.get(locoId));
 		return props();
 	}
 
@@ -204,7 +207,7 @@ public class Train implements Comparable<Train>,Constants {
 		LOG.debug("addCar({})",params);
 		if (!params.containsKey(CAR_ID)) return t("No car id passed to Train.addCar!");
 		Car car = Car.get(params.get(CAR_ID));
-		if (car == null) return t("No car with id \"{}\" known!",params.get(CAR_ID));
+		if (isNull(car)) return t("No car with id \"{}\" known!",params.get(CAR_ID));
 		if (car instanceof Locomotive) {
 			locos.add((Locomotive) car);
 		} else cars.add(car);
@@ -212,7 +215,7 @@ public class Train implements Comparable<Train>,Constants {
 	}
 
 	public void add(Car car) {
-		if (car == null) return;
+		if (isNull(car)) return;
 		if (car instanceof Locomotive) {
 			locos.add((Locomotive) car);
 		} else cars.add(car);
@@ -220,29 +223,13 @@ public class Train implements Comparable<Train>,Constants {
 	}
 	
 	private String automatic() {
-		if (autopilot == null) {
+		if (isNull(autopilot)) {
 			autopilot = new Autopilot();
 			autopilot.start();
 		}
 		return t("{} now in auto-mode",this);
 	}
 	
-	public Block block() {
-		return block;
-	}
-	
-	public Train block(Block block, boolean resetPreviousBlocks) {
-		if (this.block == block) return this; // nothing to update
-		if (this.block != null) {
-			this.block.trailingTrain(this);
-			previousBlocks.add(this.block);
-		}
-		this.block = block;
-		block.trainHead(this);
-		if (resetPreviousBlocks) resetPreviousBlocks();
-		return this;
-	}
-
 	private Tag carList() {
 		Tag locoProp = new Tag("li").content(t("Cars:"));
 		Tag locoList = new Tag("ul").clazz("carlist");
@@ -273,7 +260,7 @@ public class Train implements Comparable<Train>,Constants {
 	
 	private static Object create(HashMap<String, String> params, Plan plan) {
 		Locomotive loco = (Locomotive) Locomotive.get(params.get(Train.LOCO_ID));
-		if (loco == null) return t("unknown locomotive: {}",params.get(ID));
+		if (isNull(loco)) return t("unknown locomotive: {}",params.get(ID));
 		Train train = new Train(loco).plan(plan);
 		if (params.containsKey(NAME)) train.name(params.get(NAME));
 		return train;
@@ -286,7 +273,7 @@ public class Train implements Comparable<Train>,Constants {
 	
 	public Train heading(Direction dir) {
 		direction = dir;
-		if (block != null) plan.place(block);
+		if (isSet(block)) plan.place(block);
 		return this;
 	}	
 	
@@ -294,10 +281,10 @@ public class Train implements Comparable<Train>,Constants {
 		JSONObject json = new JSONObject();
 		json.put(ID, id);
 		json.put(NAME,name);
-		if (route != null) json.put(ROUTE, route.id());
+		if (isSet(route)) json.put(ROUTE, route.id());
-		if (direction != null) json.put(DIRECTION, direction);
+		if (isSet(direction)) json.put(DIRECTION, direction);
 		json.put(PUSH_PULL, pushPull);
-		if (name != null)json.put(NAME, name);
+		if (isSet(name))json.put(NAME, name);
 		Vector<Integer> locoIds = new Vector<Integer>();
 		for (Locomotive loco : locos) locoIds.add(loco.id());
 		json.put(LOCOS, locoIds);
@@ -326,7 +313,7 @@ public class Train implements Comparable<Train>,Constants {
 	public static void loadAll(String filename, Plan plan) throws IOException {
 		BufferedReader file = new BufferedReader(new FileReader(filename));
 		String line = file.readLine();
-		while (line != null) {
+		while (isSet(line)) {
 			JSONObject json = new JSONObject(line);
 			
 			int id = json.getInt(ID);
@@ -405,7 +392,7 @@ public class Train implements Comparable<Train>,Constants {
 	}
 
 	public String name() {
-		return (name != null ? name : locos.firstElement().name());
+		return (isSet(name) ? name : locos.firstElement().name());
 	}
 	
 	private Train name(String newName) {
@@ -441,11 +428,11 @@ public class Train implements Comparable<Train>,Constants {
 		carList().addTo(propList);
 		new Tag("li").content(t("length: {}",length())).addTo(propList);
 		
-		if (block != null) {
+		if (isSet(block)) {
 			new Tag("li").content(t("Current location: {}",block)).addTo(propList);
 			Tag actions = new Tag("li").clazz().content(t("Actions:")+NBSP);
 			new Button(t("start"),"train("+id+",'"+ACTION_START+"')").addTo(actions);
-			if (autopilot == null) {
+			if (isNull(autopilot)) {
 				new Button(t("auto"),"train("+id+",'"+ACTION_AUTO+"')").addTo(actions);
 			} else {
 				new Button(t("quit autopilot"),"train("+id+",'"+ACTION_QUIT+"')").addTo(actions);
@@ -453,10 +440,10 @@ public class Train implements Comparable<Train>,Constants {
 			actions.addTo(propList);
 
 		}
-		if (route != null) {
+		if (isSet(route)) {
 			new Tag("li").content(t("Current route: {}",route)).addTo(propList);
 		}
-		if (direction != null) new Tag("li").content(t("Direction: heading {}",direction)).addTo(propList);
+		if (isSet(direction)) new Tag("li").content(t("Direction: heading {}",direction)).addTo(propList);
 		
 		Tag tagList = new Tag("ul");
 		for (String tag : tags()) new Tag("li").content(tag).addTo(tagList);
@@ -474,26 +461,13 @@ public class Train implements Comparable<Train>,Constants {
 	}
 
 	public Object quitAutopilot() {
-		if (autopilot != null) {
+		if (isSet(autopilot)) {
 			autopilot.stop = true;
 			autopilot = null;
 			return t("{} stopping at next block.",this);
 		} else return t("autopilot not active.");
 	}
 
-	public void removeFromBlock(Block block) {
-		if (block.trainHead() == this) block.trainHead(null);
-		if (this.block == block) this.block = null;
-		previousBlocks.remove(block);		
-	}
-	
-	public void resetPreviousBlocks() {
-		for (Block block : previousBlocks) {
-			if (block.trainHead() == this || block.trailingTrain() == this) block.unlock();
-		}
-		previousBlocks.clear();
-	}
-
 	public static void saveAll(String filename) throws IOException {
 		BufferedWriter file = new BufferedWriter(new FileWriter(filename));
 		for (Entry<Integer, Train> entry:trains.entrySet()) {
@@ -504,7 +478,7 @@ public class Train implements Comparable<Train>,Constants {
 	}
 	
 	public static Select selector(Train preselected,Collection<Train> exclude) {
-		if (exclude == null) exclude = new Vector<Train>();
+		if (isNull(exclude)) exclude = new Vector<Train>();
 		Select select = new Select(Train.HEAD);
 		new Tag("option").attr("value","0").content(t("unset")).addTo(select);
 		for (Train train : Train.list()) {			
@@ -522,21 +496,23 @@ public class Train implements Comparable<Train>,Constants {
 	}
 	
 	public String start() throws IOException {
-		if (block == null) return t("{} not in a block",this);
+		if (isNull(block)) return t("{} not in a block",this);
-		if (route != null) route.reset(); // reset route previously chosen
+		Context context = isSet(route) ? new Context( route ) : new Context( this);
-		Context context = new Context(this);
-		route = chooseRoute(context);
-		if (route == null) return t("No free routes from {}",block);
 		
+		if (isSet(context.route)) context.route.reset(); // reset route previously chosen
+		
+		route = chooseRoute(context);
+		if (isNull(route)) return t("No free routes from {}",block);		
 		if (!route.lock()) return t("Was not able to lock {}",route);
+		
 		if (direction != route.startDirection) turn();
 		
 		String error = null;
 		if (!route.setTurnouts()) error = t("Was not able to set all turnouts!");
-		if (error == null && !route.fireSetupActions(context)) error = t("Was not able to fire all setup actions of route!");
+		if (isNull(error) && !route.fireSetupActions(context)) error = t("Was not able to fire all setup actions of route!");
-		if (error == null && !route.setSignals(null)) error = t("Was not able to set all signals!");
+		if (isNull(error) && !route.setSignals(null)) error = t("Was not able to set all signals!");
-		if (error == null && !route.train(this)) error = t("Was not able to assign {} to {}!",this,route);
+		if (isNull(error) && !route.train(this)) error = t("Was not able to assign {} to {}!",this,route);
-		if (error != null) {
+		if (isSet(error)) {
 			route.reset();
 			return error;
 		}
@@ -547,13 +523,6 @@ public class Train implements Comparable<Train>,Constants {
 	private Object stopNow() {
 		quitAutopilot();
 		setSpeed(0);
-		if (route != null) try {
-			route.unlock();
-			route.endBlock().trainHead(null);
-			route.startBlock().trainHead(this);
-		} catch (IOException e) {
-			e.printStackTrace();			
-		}
 		route = null;
 		return t("Stopped {}.",this);
 	}
@@ -564,16 +533,15 @@ public class Train implements Comparable<Train>,Constants {
 	
 	@Override
 	public String toString() {
-		return name != null ? name : locos.firstElement().name();
+		return isSet(name) ? name : locos.firstElement().name();
 	}
 	
 	public Object turn() {
 		LOG.debug("train.turn()");
-		if (direction != null) {
+		if (isSet(direction)) {
 			direction = direction.inverse();
 			for (Locomotive loco : locos) loco.turn(); 
 		}
-		if (block != null) plan.place(block.trainHead(this));
 		return t("{} turned.",this);
 	}
 
@@ -593,4 +561,48 @@ public class Train implements Comparable<Train>,Constants {
 
 		return this;
 	}
+
+	public void set(Block newBlock) {
+		block = newBlock;
+		if (isSet(block)) block.set(this);
+	}
+
+	public Tile headPos() {
+		return trace.getFirst();
+	}
+
+	public void addToTrace(Vector<Tile> newTiles) {
+		boolean active = trace.isEmpty();
+		for (Tile tile : newTiles) {
+			if (active) {
+				trace.addFirst(tile);
+				System.err.println(trace);
+			} else {
+				Tile dummy = trace.getFirst();
+				if (dummy == tile) {
+					active = true;
+				};
+			}			
+		}
+		showTrace();
+	}
+
+	public void showTrace() {
+ 		int remainingLength = length();
+		for (int i=0; i<trace.size(); i++) {
+			Tile tile = trace.get(i);
+			if (remainingLength>0) {
+				remainingLength-=tile.length();
+				tile.set(this);
+			} else {
+				tile.set(null);
+				trace.remove(i);
+				i--; // do not move to next index: remove shifted the next index towards us
+			}
+		}
+	}
+
+	public void dropTrace() {
+		while (!trace.isEmpty()) trace.removeFirst().set(null);
+	}
 }

src/main/java/de/srsoftware/web4rail/tiles/Block.java

@@ -22,7 +22,6 @@ public abstract class Block extends StretchableTile{
 	
 	private static final String ALLOW_TURN = "allowTurn";
 	public boolean turnAllowed = false;
-	private Train trailingTrain = null;
 		
 	@Override
 	public JSONObject config() {
@@ -30,11 +29,6 @@ public abstract class Block extends StretchableTile{
 		config.put(NAME, name);
 		return config;
 	}
-	
-	@Override
-	public boolean isFree() {
-		return super.isFree() && trailingTrain == null;
-	}
 		
 	@Override
 	public JSONObject json() {
@@ -61,7 +55,7 @@ public abstract class Block extends StretchableTile{
 		
 		new Checkbox(ALLOW_TURN,t("Turn allowed"),turnAllowed).addTo(new Tag("p")).addTo(form);
 
-		Select select = Train.selector(trainHead, null);
+		Select select = Train.selector(train, null);
 		select.addTo(new Label(t("Train:")+NBSP)).addTo(new Tag("p")).addTo(form);
 		
 		return form;
@@ -71,10 +65,10 @@ public abstract class Block extends StretchableTile{
 	public Tag propMenu() {
 		Tag window = super.propMenu();
 		
-		if (trainHead != null) {
+		if (isSet(train)) {
-			window.children().insertElementAt(new Button(t("stop"),"train("+trainHead.id+",'"+ACTION_STOP+"')"), 1);
+			window.children().insertElementAt(new Button(t("stop"),"train("+train.id+",'"+ACTION_STOP+"')"), 1);
-			window.children().insertElementAt(new Button(t("start"),"train("+trainHead.id+",'"+ACTION_START+"')"), 1);
+			window.children().insertElementAt(new Button(t("start"),"train("+train.id+",'"+ACTION_START+"')"), 1);
-			window.children().insertElementAt(trainHead.link("span"), 1);
+			window.children().insertElementAt(train.link("span"), 1);
 			window.children().insertElementAt(new Tag("h4").content(t("Train:")), 1);
 		}
 		return window;
@@ -84,12 +78,11 @@ public abstract class Block extends StretchableTile{
 
 	@Override
 	public Tag tag(Map<String, Object> replacements) throws IOException {
-		if (replacements == null) replacements = new HashMap<String, Object>();
+		if (isNull(replacements)) replacements = new HashMap<String, Object>();
 		replacements.put("%text%",name);
-		if (trailingTrain != null) replacements.put("%text%","("+trailingTrain.name()+")");
+		if (isSet(train)) replacements.put("%text%",train.directedName());
-		if (trainHead != null) replacements.put("%text%",trainHead.directedName());
 		Tag tag = super.tag(replacements);
-		if (trainHead != null || trailingTrain != null) tag.clazz(tag.get("class")+" occupied");
+		if (isSet(train)) tag.clazz(tag.get("class")+" occupied");
 		return tag;
 	}
 	
@@ -103,32 +96,19 @@ public abstract class Block extends StretchableTile{
 		return getClass().getSimpleName()+"("+name+") @ ("+x+","+y+")";
 	}
 	
-	public void trailingTrain(Train train) {
-		trailingTrain = train;
-		this.trainHead = null;
-		plan.place(this);
-	}
-
-	public Train trailingTrain() {
-		return trailingTrain;
-	}
-
-	@Override
-	public void unlock() {
-		trailingTrain = null;
-		super.unlock();
-	}
-	
 	@Override
 	public Tile update(HashMap<String, String> params) throws IOException {		
 		if (params.containsKey(NAME)) name=params.get(NAME);
 		if (params.containsKey(Train.HEAD)) {
 			int trainId = Integer.parseInt(params.get(Train.HEAD));
 			if (trainId == 0) {
-				trainHead(null);
+				train = null;
 			} else {
-				Train t = Train.get(trainId);
+				Train dummy = Train.get(trainId);
-				if (t != null) trainHead = t.block(this,true);
+				if (isSet(dummy) && dummy != train) {
+					dummy.set(this);
+					dummy.dropTrace();
+				}
 			}
 		}
 		turnAllowed = params.containsKey(ALLOW_TURN) && params.get(ALLOW_TURN).equals("on");

src/main/java/de/srsoftware/web4rail/tiles/BlockH.java

@@ -15,7 +15,7 @@ public class BlockH extends Block{
 	public Map<Connector, State> connections(Direction from) {
 		switch (from) {
 			case WEST:
-				return Map.of(new Connector(x+len(),y,Direction.WEST),State.UNDEF);
+				return Map.of(new Connector(x+width(),y,Direction.WEST),State.UNDEF);
 			case EAST:
 				return Map.of(new Connector(x-1,y,Direction.EAST),State.UNDEF);
 			default:
@@ -24,12 +24,17 @@ public class BlockH extends Block{
 	}
 		
 	@Override
-	public int len() {
+	public int width() {
-		return length;
+		return stretch;
 	}
 	
 	@Override
 	public List<Connector> startPoints() {
-		return List.of(new Connector(x-1, y, Direction.EAST),new Connector(x+len(), y, Direction.WEST));
+		return List.of(new Connector(x-1, y, Direction.EAST),new Connector(x+width(), y, Direction.WEST));
+	}
+
+	@Override
+	protected String stretchType() {
+		return t("Width");
 	}
 }

src/main/java/de/srsoftware/web4rail/tiles/BlockV.java

@@ -25,11 +25,16 @@ public class BlockV extends Block{
 	
 	@Override
 	public int height() {
-		return length;
+		return stretch;
 	}
 	
 	@Override
 	public List<Connector> startPoints() {
 		return List.of(new Connector(x,y-1,Direction.SOUTH),new Connector(x,y+height(),Direction.NORTH));
+	}
+
+	@Override
+	protected String stretchType() {
+		return t("Height");
 	}	
 }

src/main/java/de/srsoftware/web4rail/tiles/CrossH.java

@@ -24,7 +24,7 @@ public class CrossH extends Cross{
 	}
 	
 	@Override
-	public int len() {
+	public int width() {
 		return 2;
 	}
 	

src/main/java/de/srsoftware/web4rail/tiles/StraightH.java

@@ -15,7 +15,7 @@ public class StraightH extends StretchableTile{
 		if (oneWay == from) return new HashMap<>();
 		switch (from) {
 			case WEST:
-				return Map.of(new Connector(x+len(),y,Direction.WEST),State.UNDEF);
+				return Map.of(new Connector(x+width(),y,Direction.WEST),State.UNDEF);
 			case EAST:
 				return Map.of(new Connector(x-1,y,Direction.EAST),State.UNDEF);
 			default:
@@ -24,12 +24,17 @@ public class StraightH extends StretchableTile{
 	}
 	
 	@Override
-	public int len() {
+	public int width() {
-		return length;
+		return stretch;
 	}
 	
 	@Override
 	public List<Direction> possibleDirections() {
 		return List.of(Direction.EAST,Direction.WEST);
 	}
+	
+	@Override
+	protected String stretchType() {
+		return t("Width");
+	}	
 }

src/main/java/de/srsoftware/web4rail/tiles/StraightV.java

@@ -25,11 +25,16 @@ public class StraightV extends StretchableTile{
 	
 	@Override
 	public int height() {
-		return length;
+		return stretch;
 	}
 	
 	@Override
 	public List<Direction> possibleDirections() {
 		return List.of(Direction.NORTH,Direction.SOUTH);
 	}
+	
+	@Override
+	protected String stretchType() {
+		return t("Height");
+	}	
 }

src/main/java/de/srsoftware/web4rail/tiles/StretchableTile.java

@@ -7,61 +7,64 @@ import java.util.Map.Entry;
 import org.json.JSONObject;
 
 import de.srsoftware.tools.Tag;
+import de.srsoftware.web4rail.tags.Input;
+import de.srsoftware.web4rail.tags.Label;
 
 public abstract class StretchableTile extends Tile {
-	private static final String LENGTH = "length";
+	private static final String STRETCH_LENGTH = "stretch";
-	public int length = 1;
+	public int stretch = 1;
 	
 	@Override
 	public JSONObject config() {
 		JSONObject config = super.config();
-		if (length != 1) config.put(LENGTH, length);
+		if (stretch != 1) config.put(STRETCH_LENGTH, stretch);
 		return config;
 	}
 	
 	@Override
 	public JSONObject json() {
 		JSONObject json = super.json();
-		if (length > 1) json.put(LENGTH, length);
+		if (stretch > 1) json.put(STRETCH_LENGTH, stretch);
 		return json;
 	}
 	
 	@Override
 	protected Tile load(JSONObject json) throws IOException {
 		super.load(json);
-		if (json.has(LENGTH)) length = json.getInt(LENGTH);
+		if (json.has(STRETCH_LENGTH)) stretch = json.getInt(STRETCH_LENGTH);
 		return this;
 	}
 	
 	@Override
 	public Tag propForm(String id) {
 		Tag form = super.propForm(id);
-		new Tag("h4").content(t("Length")).addTo(form);
+		new Tag("h4").content(stretchType()).addTo(form);
-		Tag label = new Tag("label").content(t("length:")+NBSP);
+		
-		new Tag("input").attr("type", "number").attr("name","length").attr("value", length).addTo(label);		
+		new Input(STRETCH_LENGTH, stretch).numeric().addTo(new Label(stretchType()+":"+NBSP)).addTo(new Tag("p")).addTo(form);
-		label.addTo(new Tag("p")).addTo(form);
 		
 		return form;
 	}
 	
-	private void setLength(String value) {
+	private void stretch(String value) {
 		try {
-			setLength(Integer.parseInt(value));
+			stretch(Integer.parseInt(value));
 		} catch (NumberFormatException nfe) {
 			LOG.warn("{} is not a valid length!",value);
 		}
 	}
 
-	public void setLength(int len) {
+	public void stretch(int len) {
-		this.length = Math.max(1, len);
+		this.stretch = Math.max(1, len);
 	}
 	
+	protected abstract String stretchType();
+	
 	@Override
 	public Tile update(HashMap<String, String> params) throws IOException {
 		for (Entry<String, String> entry : params.entrySet()) {
 			switch (entry.getKey()) {
-				case LENGTH:
+				case STRETCH_LENGTH:
-					setLength(entry.getValue());
+					stretch(entry.getValue());
 					break;
 			}
 		}

src/main/java/de/srsoftware/web4rail/tiles/Tile.java

@@ -23,8 +23,8 @@ import org.slf4j.LoggerFactory;
 import de.keawe.tools.translations.Translation;
 import de.srsoftware.tools.Tag;
 import de.srsoftware.web4rail.Application;
+import de.srsoftware.web4rail.BaseClass;
 import de.srsoftware.web4rail.Connector;
-import de.srsoftware.web4rail.Constants;
 import de.srsoftware.web4rail.Plan;
 import de.srsoftware.web4rail.Plan.Direction;
 import de.srsoftware.web4rail.Route;
@@ -36,10 +36,12 @@ import de.srsoftware.web4rail.tags.Form;
 import de.srsoftware.web4rail.tags.Input;
 import de.srsoftware.web4rail.tags.Radio;
 
-public abstract class Tile implements Constants{
+public abstract class Tile extends BaseClass{
 	protected static Logger LOG = LoggerFactory.getLogger(Tile.class);	
+	private static int DEFAUT_LENGTH = 5;
 	
 	public    static final String ID         = "id";
+	private   static final String LENGTH     = "length";
 	private   static final String LOCKED     = "locked";
 	private   static final String OCCUPIED   = "occupied";
 	private   static final String ONEW_WAY   = "one_way";
@@ -48,16 +50,17 @@ public abstract class Tile implements Constants{
 	private   static final String TYPE       = "type";
 	private   static final String X          = "x";
 	private   static final String Y          = "y";
+
 	
 	
-	private  boolean          disabled  = false;
+	private   boolean         disabled  = false;
+	private   int             length    = DEFAUT_LENGTH;
 	protected Direction       oneWay    = null;
 	protected Plan            plan      = null;;
 	protected Route           route     = null;
 	private   HashSet<Route>  routes    = new HashSet<>();
 	protected HashSet<Shadow> shadows   = new HashSet<>();
-	protected Train           trainHead = null;	
+	protected Train           train     = null;	
-	protected Train           trainTail = null;
 	public    Integer         x         = null;
 	public    Integer         y         = null;
 
@@ -66,8 +69,8 @@ public abstract class Tile implements Constants{
 		classes.add("tile");
 		classes.add(getClass().getSimpleName());
 		if (isSet(route)) classes.add(LOCKED);
-		if (isSet(trainHead) || isSet(trainTail)) classes.add(OCCUPIED);
+		if (isSet(train)) classes.add(OCCUPIED);
-		if (disabled) classes.add(DISABLED);
+		if (disabled)     classes.add(DISABLED);
 		return classes;
 	}
 
@@ -93,7 +96,7 @@ public abstract class Tile implements Constants{
 	}
 
 	public boolean isFree() {
-		return !(disabled || isSet(route) || isSet(trainHead) || isSet(trainTail));
+		return !(disabled || isSet(route) || isSet(train));
 	}
 	
 	public int height() {
@@ -115,14 +118,6 @@ public abstract class Tile implements Constants{
 		tile.load(json);
 		plan.set(tile.x, tile.y, tile);
 	}
-	
-	protected static boolean isNull(Object o) {
-		return o==null;
-	}
-
-	protected static boolean isSet(Object o) {
-		return o != null;
-	}
 
 	public JSONObject json() {
 		JSONObject json = new JSONObject();
@@ -132,13 +127,18 @@ public abstract class Tile implements Constants{
 		if (isSet(route))     json.put(ROUTE, route.id());
 		if (isSet(oneWay))    json.put(ONEW_WAY, oneWay);
 		if (disabled)         json.put(DISABLED, true);
-		if (isSet(trainHead)) json.put(Train.HEAD, trainHead.id);
+		if (isSet(train))     json.put(REALM_TRAIN, train.id);
-		if (isSet(trainTail)) json.put(Train.TAIL, trainTail.id);
+		json.put(LENGTH, length);
 		return json;
 	}
 	
-	public int len() {
+	public int length() {
-		return 1;
+		return length;
+	}
+	
+	public Tile length(int newLength) {
+		length = newLength;
+		return this;
 	}
 	
 	public static void loadAll(String filename, Plan plan) throws IOException {		
@@ -163,10 +163,10 @@ public abstract class Tile implements Constants{
 		JSONObject pos = json.getJSONObject(POS);
 		x = pos.getInt(X);
 		y = pos.getInt(Y);
-		if (json.has(ONEW_WAY))   oneWay    = Direction.valueOf(json.getString(ONEW_WAY));
+		if (json.has(DISABLED))    disabled  = json.getBoolean(DISABLED);
-		if (json.has(DISABLED))   disabled  = json.getBoolean(DISABLED);
+		if (json.has(LENGTH))	   length    = json.getInt(LENGTH);
-		if (json.has(Train.HEAD)) trainHead = Train.get(json.getInt(Train.HEAD));
+		if (json.has(ONEW_WAY))    oneWay    = Direction.valueOf(json.getString(ONEW_WAY));
-		if (json.has(Train.TAIL)) trainTail = Train.get(json.getInt(Train.TAIL));
+		if (json.has(REALM_TRAIN)) train = Train.get(json.getInt(REALM_TRAIN));
 		return this;
 	}
 		
@@ -195,7 +195,6 @@ public abstract class Tile implements Constants{
 		new Input(REALM, REALM_PLAN).hideIn(form);
 		new Input(ID,id()).hideIn(form);
 
-
 		List<Direction> pd = possibleDirections();
 		if (!pd.isEmpty()) {
 			new Tag("h4").content(t("One way:")).addTo(form);
@@ -211,6 +210,8 @@ public abstract class Tile implements Constants{
 		Window window = new Window("tile-properties",t("Properties of {} @ ({},{})",title(),x,y));
 		String formId = "tile-properties-"+id();
 		Tag form = propForm(formId);
+		new Tag("h4").content(t("Length")).addTo(form);
+		new Input(LENGTH,length).numeric().addTo(form);
 		new Tag("h4").content(t("Availability")).addTo(form);
 		new Checkbox(DISABLED, t("disabled"), disabled).addTo(form);
 		new Button(t("Apply"),"submitForm('"+formId+"')").addTo(form);
@@ -285,7 +286,7 @@ public abstract class Tile implements Constants{
 	}
 
 	public Tag tag(Map<String,Object> replacements) throws IOException {
-		int width = 100*len();
+		int width = 100*width();
 		int height = 100*height();
 		if (isNull(replacements)) replacements = new HashMap<String, Object>();
 		replacements.put("%width%",width);
@@ -298,7 +299,7 @@ public abstract class Tile implements Constants{
 				.attr("name", getClass().getSimpleName())				
 				.attr("viewbox", "0 0 "+width+" "+height);
 				if (isSet(x)) style="left: "+(30*x)+"px; top: "+(30*y)+"px;";
-				if (len()>1) style+=" width: "+(30*len())+"px;";
+				if (width()>1) style+=" width: "+(30*width())+"px;";
 				if (height()>1) style+=" height: "+(30*height())+"px;";
 		
 		if (!style.isEmpty()) svg.style(style);
@@ -355,20 +356,19 @@ public abstract class Tile implements Constants{
 		return t("{}({},{})",getClass().getSimpleName(),x,y) ;
 	}
 	
-	public Train trainHead() {
+	public Train train() {
-		return trainHead;
+		return train;
 	}
 	
-	public Tile trainHead(Train train) {
+	public Tile set(Train newTrain) {
-		if (this.trainHead == train) return this; // nothing to update
+		if (newTrain == train) return this; // nothing to update
-		this.trainHead = train;		
+		this.train = newTrain;		
 		return plan.place(this);
 	}	
 
 	public void unlock() {
-		route     = null;
+		route = null;
-		trainHead = null;
+		train = null;
-		trainTail = null;
 		plan.place(this);
 	}
 
@@ -383,7 +383,13 @@ public abstract class Tile implements Constants{
 			}
 		}
 		disabled = "on".equals(params.get(DISABLED));
+		String len = params.get(LENGTH);
+		if (isSet(len)) length(Integer.parseInt(len));
 		plan.stream(tag(null).toString());
 		return this;
 	}
+	
+	public int width() {
+		return 1;
+	}
 }