Count requests instead of accesses

Change counter semantic to avoid starvation.

ds/trains0.xml

@@ -135,8 +135,8 @@ id_tAB tail()
 			<name x="331" y="94">Free</name>
 		</location>
 		<location id="id9" x="212" y="-68">
-			<name x="221" y="-59">OnlyAB</name>
-			<label kind="comments" x="280" y="-59">At least one train on AB ;
+			<name x="238" y="-59">OnlyAB</name>
+			<label kind="comments" x="297" y="-59">At least one train on AB ;
 and no train blocked on B</label>
 		</location>
 		<location id="id10" x="212" y="263">
@@ -144,18 +144,35 @@ and no train blocked on B</label>
 		</location>
 		<location id="id11" x="-153" y="-68">
 			<name x="-272" y="-68">RequestFromB</name>
-			<label kind="comments" x="-493" y="-102">Waiting for AB trains to leave shared section;
+			<label kind="comments" x="-484" y="-42">Waiting for AB trains to leave shared section;
 some other trains are waiting on B.</label>
 		</location>
 		<location id="id12" x="-153" y="263">
-			<name x="-280" y="254">RequestFromA</name>
+			<name x="-272" y="246">RequestFromA</name>
 		</location>
 		<init ref="id8"/>
 		<transition>
+			<source ref="id11"/>
+			<target ref="id11"/>
+			<label kind="select" x="-263" y="-221">e:id_tAB</label>
+			<label kind="synchronisation" x="-263" y="-204">accesAB[e]!</label>
+			<nail x="-187" y="-187"/>
+			<nail x="-263" y="-187"/>
+		</transition>
+		<transition>
+			<source ref="id12"/>
+			<target ref="id12"/>
+			<label kind="select" x="-255" y="323">e:id_tBA</label>
+			<label kind="synchronisation" x="-255" y="340">accesBA[e] !</label>
+			<nail x="-196" y="323"/>
+			<nail x="-256" y="323"/>
+		</transition>
+		<transition>
 			<source ref="id8"/>
 			<target ref="id9"/>
 			<label kind="select" x="144" y="17">e:id_tAB</label>
 			<label kind="synchronisation" x="102" y="34">requestAB[e] ?</label>
+			<label kind="assignment" x="161" y="51">ab ++</label>
 			<nail x="212" y="59"/>
 		</transition>
 		<transition>
@@ -163,6 +180,7 @@ some other trains are waiting on B.</label>
 			<target ref="id10"/>
 			<label kind="select" x="144" y="136">e:id_tBA</label>
 			<label kind="synchronisation" x="102" y="153">requestBA[e] ?</label>
+			<label kind="assignment" x="161" y="170">ba ++</label>
 			<nail x="212" y="144"/>
 		</transition>
 		<transition>
@@ -188,24 +206,27 @@ some other trains are waiting on B.</label>
 		<transition>
 			<source ref="id10"/>
 			<target ref="id12"/>
-			<label kind="select" x="-8" y="229">e:id_tAB</label>
-			<label kind="synchronisation" x="-8" y="246">requestAB[e] ?</label>
+			<label kind="select" x="-42" y="212">e:id_tAB</label>
+			<label kind="synchronisation" x="-42" y="229">requestAB[e] ?</label>
+			<label kind="assignment" x="-42" y="246">ab ++</label>
 		</transition>
 		<transition>
 			<source ref="id10"/>
 			<target ref="id10"/>
-			<label kind="select" x="93" y="339">e:id_tBA</label>
-			<label kind="synchronisation" x="93" y="356">requestBA[e] ?</label>
-			<nail x="170" y="331"/>
-			<nail x="102" y="331"/>
+			<label kind="select" x="323" y="263">e:id_tBA</label>
+			<label kind="synchronisation" x="323" y="280">requestBA[e] ?</label>
+			<label kind="assignment" x="323" y="298">ba ++</label>
+			<nail x="314" y="323"/>
+			<nail x="314" y="263"/>
 		</transition>
 		<transition>
 			<source ref="id9"/>
 			<target ref="id9"/>
-			<label kind="select" x="93" y="-229">e:id_tAB</label>
-			<label kind="synchronisation" x="93" y="-212">requestAB[e] ?</label>
-			<nail x="178" y="-187"/>
-			<nail x="102" y="-187"/>
+			<label kind="select" x="331" y="-153">e:id_tAB</label>
+			<label kind="synchronisation" x="331" y="-136">requestAB[e] ?</label>
+			<label kind="assignment" x="331" y="-119">ab ++</label>
+			<nail x="323" y="-153"/>
+			<nail x="323" y="-68"/>
 		</transition>
 		<transition>
 			<source ref="id11"/>
@@ -225,8 +246,9 @@ some other trains are waiting on B.</label>
 		<transition>
 			<source ref="id9"/>
 			<target ref="id11"/>
-			<label kind="select" x="8" y="-102">e:id_tBA</label>
-			<label kind="synchronisation" x="8" y="-85">requestBA[e] ?</label>
+			<label kind="select" x="-34" y="-119">e:id_tBA</label>
+			<label kind="synchronisation" x="-34" y="-102">requestBA[e] ?</label>
+			<label kind="assignment" x="-34" y="-85">ba ++</label>
 		</transition>
 		<transition>
 			<source ref="id10"/>
@@ -240,20 +262,18 @@ some other trains are waiting on B.</label>
 		<transition>
 			<source ref="id10"/>
 			<target ref="id10"/>
-			<label kind="select" x="357" y="263">e:id_tBA</label>
-			<label kind="synchronisation" x="357" y="280">accesBA[e] !</label>
-			<label kind="assignment" x="357" y="297">ba ++</label>
-			<nail x="348" y="263"/>
-			<nail x="348" y="331"/>
+			<label kind="select" x="110" y="340">e:id_tBA</label>
+			<label kind="synchronisation" x="110" y="357">accesBA[e] !</label>
+			<nail x="195" y="331"/>
+			<nail x="110" y="331"/>
 		</transition>
 		<transition>
 			<source ref="id9"/>
 			<target ref="id9"/>
-			<label kind="select" x="340" y="-153">e:id_tAB</label>
-			<label kind="synchronisation" x="340" y="-136">accesAB[e] !</label>
-			<label kind="assignment" x="340" y="-119">ab++</label>
-			<nail x="331" y="-68"/>
-			<nail x="331" y="-178"/>
+			<label kind="select" x="85" y="-229">e:id_tAB</label>
+			<label kind="synchronisation" x="85" y="-212">accesAB[e] !</label>
+			<nail x="187" y="-187"/>
+			<nail x="85" y="-187"/>
 		</transition>
 		<transition>
 			<source ref="id9"/>