diff --git a/src/modules/simu/simuv5/collide.cpp b/src/modules/simu/simuv5/collide.cpp
index 638b13809..3f57a27dd 100644
--- a/src/modules/simu/simuv5/collide.cpp
+++ b/src/modules/simu/simuv5/collide.cpp
@@ -418,10 +418,30 @@ static void SimCarCollideResponse(void * /*dummy*/, DtObjectRef obj1, DtObjectRe
     }
 }
 
+// Static object and shape list.
+// TODO: Dynamic implementation.
+static DtShapeRef fixedobjects[100];
+// Id to the next free slot in fixedobjects.
+static size_t fixedid;
+
+static bool isFixedObject(DtObjectRef obj)
+{
+    for (size_t i = 0; i < fixedid; i++)
+    {
+        if (obj == &(fixedobjects[i]))
+            return true;
+    }
+    return false;
+}
+
 // Collision response for walls.
 // TODO: Separate common code with car-car collision response.
 static void SimCarWallCollideResponse(void *clientdata, DtObjectRef obj1, DtObjectRef obj2, const DtCollData *collData)
 {
+    // ignore wall with wall collision
+    if (isFixedObject(obj1) && isFixedObject(obj2))
+        return;
+
     tCar* car;		// The car colliding with the wall.
     float nsign;	// Normal direction correction for collision plane.
     sgVec2 p;		// Cars collision point delivered by solid.
@@ -569,17 +589,9 @@ void SimCollideRemoveCar(tCar *car, int nbcars)
     }
 }
 
-// Static object and shape list.
-// TODO: Dynamic implementation.
-static DtShapeRef fixedobjects[100];
-// Id to the next free slot in fixedobjects.
-static unsigned int fixedid;
-
 void SimCarCollideShutdown(int nbcars)
 {
-    int i;
-
-    for (i = 0; i < nbcars; i++)
+    for (int i = 0; i < nbcars; i++)
     {
         // Check if car has not been removed already (wrecked).
         if (SimCarTable[i].shape != NULL)
@@ -589,8 +601,7 @@ void SimCarCollideShutdown(int nbcars)
         }
     }
 
-    unsigned int j;
-    for (j = 0; j < fixedid; j++)
+    for (size_t j = 0; j < fixedid; j++)
     {
         dtClearObjectResponse(&fixedobjects[j]);
         dtDeleteObject(&fixedobjects[j]);
@@ -637,9 +648,19 @@ static tTrackSeg *getFirstWallStart(tTrackSeg *start, int side)
     return NULL;
 }
 
-// Create the left walls, start must point to a segment with a wall on the left and a leading
-// non wall segment.
-// FIXME: Does not work for a closed ring "by design".
+static tdble distance(const t3Dd &p1, const t3Dd &p2)
+{
+    tdble dx = p1.x - p2.x;
+    tdble dy = p1.y - p2.y;
+    tdble dz = p1.z - p2.z;
+
+    return sqrt(dx * dx + dy * dy + dz * dz);
+}
+
+// Create the walls, start must point to a segment with a wall.
+//
+// Solid has problems when 2 walls touch so we nolonger break up walls that have changes
+// in height or width. This should not be a problem as long as cars stay on the ground.
 void buildWalls(tTrackSeg *start, int side) {
 
     if (start == NULL) {
@@ -665,12 +686,8 @@ void buildWalls(tTrackSeg *start, int side) {
             t3Dd evr = s->vertex[TR_ER];
             static float weps = 0.01f;
 
-            // Close the start with a ploygon?
-            if (p == NULL || p->style != TR_WALL ||
-                (fabs(p->vertex[TR_EL].x - svl.x) > weps) ||
-                (fabs(p->vertex[TR_ER].x - svr.x) > weps) ||
-                (fabs(h - p->height) > weps) ||
-                fixedid == 0)
+            // Close the wall start with a ploygon?
+            if (p == NULL || p->style != TR_WALL || fixedid == 0)
             {
                 // Enough space in array?
                 if (fixedid >= sizeof(fixedobjects)/sizeof(fixedobjects[0]))
@@ -698,6 +715,13 @@ void buildWalls(tTrackSeg *start, int side) {
                 dtEnd();
             }
 
+            // fill in hole if width changes
+            if (p != NULL && p->style == TR_WALL && (distance(p->vertex[TR_EL], svl) > weps || distance(p->vertex[TR_ER], svr) > weps))
+            {
+                // TODO: we can get away with not adding this polygon if the change of width
+                // is small but it will be a problem if the hole is bigger than a car.
+            }
+
             // Build sides, left, top, right. Depending on how we want to use it we
             // can remove top perhaps.
             // TODO: do we want the top poly?
@@ -732,10 +756,7 @@ void buildWalls(tTrackSeg *start, int side) {
             }
 
             // Close the end with a ploygon?
-            if (n == NULL || n->style != TR_WALL ||
-                (fabs(n->vertex[TR_SL].x - evl.x) > weps) ||
-                (fabs(n->vertex[TR_SR].x - evr.x) > weps) ||
-                (fabs(h - n->height) > weps))
+            if (n == NULL || n->style != TR_WALL)
             {
                 if (close == true)
                 {
@@ -754,7 +775,6 @@ void buildWalls(tTrackSeg *start, int side) {
                     GfError("Shape not open %s, line %d\n", __FILE__, __LINE__);
                 }
             }
-
         }
 
         current = current->next;
@@ -799,8 +819,7 @@ SimCarCollideInit(tTrack *track)
         buildWalls(firstleft, TR_SIDE_LFT);
         buildWalls(firstright, TR_SIDE_RGT);
 
-        unsigned int i;
-        for (i = 0; i < fixedid; i++) {
+        for (size_t i = 0; i < fixedid; i++) {
             dtCreateObject(&fixedobjects[i], fixedobjects[i]);
             dtSetObjectResponse(&fixedobjects[i], SimCarWallCollideResponse, DT_SMART_RESPONSE, &fixedobjects[i]);
         }