diff --git a/src/app/services/formulaire.service.ts b/src/app/services/formulaire.service.ts
index 9e3879d8ada618982c1343abe86977b6d6e587ef..3cb284a73316c3b3af529e91ea66439e084f72cb 100644
--- a/src/app/services/formulaire.service.ts
+++ b/src/app/services/formulaire.service.ts
@@ -14,7 +14,14 @@ import {
     Props,
     Cloisons,
     CloisonAval,
-    SPP
+    SPP,
+    PreBarrage,
+    PbBassin,
+    PbBassinParams,
+    LoiDebit,
+    PbCloison,
+    CreateStructure,
+    Structure
 } from "jalhyd";
 
 import { ApplicationSetupService } from "./app-setup.service";
@@ -418,6 +425,32 @@ export class FormulaireService extends Observable {
             newDownWall.addChild(newDownwallDevice);
             f.pabNub.downWall = newDownWall;
         }
+
+        // when creating a new PreBarrage, add one basin and two walls with one
+        // device each (when loading session, those items are already present)
+        if (
+            f instanceof FormulairePrebarrage
+            && f.currentNub instanceof PreBarrage
+            && f.currentNub.children.length === 0
+        ) {
+            // 1 basin
+            f.currentNub.addChild(new PbBassin(new PbBassinParams(13.80, 95)));
+            // 1st wall
+            f.currentNub.addChild(new PbCloison(undefined, f.currentNub.children[0] as PbBassin));
+            const s1: Structure = CreateStructure(LoiDebit.WeirCunge80);
+            s1.prms.ZDV.singleValue = 95.30;
+            s1.getParameter("L").singleValue = 0.4;
+            s1.getParameter("CdGR").singleValue = 1.04;
+            f.currentNub.children[1].addChild(s1);
+            // 2nd wall
+            f.currentNub.addChild(new PbCloison(f.currentNub.children[0] as PbBassin, undefined));
+            const s2: Structure = CreateStructure(LoiDebit.WeirCunge80);
+            s2.prms.ZDV.singleValue = 95.30;
+            s2.getParameter("L").singleValue = 0.4;
+            s2.getParameter("CdGR").singleValue = 1.04;
+            f.currentNub.children[2].addChild(s2);
+        }
+
         this.notifyObservers({
             "action": "createForm",
             "form": f