Make the acces chanel urgent

And add them to counter testing transition.

The purpose is to prevent the starvation.

But it does not seem to work.

ds/trains0.xml

@@ -15,7 +15,8 @@ typedef int[0,NBA-1] id_tBA;
 
 int ab=0, ba=0;
 
-chan        accesAB[NAB], accesBA[NBA], libAB[NAB], libBA[NBA], requestAB[NAB], requestBA[NBA];
+chan        libAB[NAB], libBA[NBA], requestAB[NAB], requestBA[NBA];
+urgent chan accesAB[NAB], accesBA[NBA];
 
 </declaration>
 	<template>
@@ -188,7 +189,9 @@ some other trains are waiting on B.</label>
 		<transition>
 			<source ref="id12"/>
 			<target ref="id9"/>
+			<label kind="select" x="-221" y="153">e:id_tAB</label>
 			<label kind="guard" x="-221" y="136">ba == 0</label>
+			<label kind="synchronisation" x="-246" y="170">accesAB[e] !</label>
 			<nail x="-153" y="144"/>
 		</transition>
 		<transition>
@@ -233,7 +236,9 @@ some other trains are waiting on B.</label>
 		<transition>
 			<source ref="id11"/>
 			<target ref="id10"/>
-			<label kind="guard" x="-221" y="42">ab == 0</label>
+			<label kind="select" x="-221" y="17">e:id_tBA</label>
+			<label kind="guard" x="-221" y="0">ab == 0</label>
+			<label kind="synchronisation" x="-246" y="34">accesBA[e] !</label>
 			<nail x="-153" y="50"/>
 		</transition>
 		<transition>