diff --git a/core/edgetypes/street.c b/core/edgetypes/street.c
index 3fcaf280..c84cafed 100644
--- a/core/edgetypes/street.c
+++ b/core/edgetypes/street.c
@@ -109,7 +109,10 @@ streetWalkGeneral(EdgePayload* superthis, State* state, WalkOptions* options, in
   Street* this = (Street*)superthis;
   State* ret = stateDup( state );
   
-  float average_grade = (this->rise-this->fall)/this->length;
+  float average_grade = 0;
+  if (this->length > 0) {
+    average_grade = (this->rise-this->fall)/this->length;
+  }
   float average_speed = speed_from_grade(options, average_grade);
   
   long delta_t = this->length / average_speed;
diff --git a/core/servicecalendar.h b/core/servicecalendar.h
index 34dea300..4526a43b 100644
--- a/core/servicecalendar.h
+++ b/core/servicecalendar.h
@@ -82,8 +82,4 @@ spPrintPeriod( ServicePeriod* this ) ;
 inline long
 spNormalizeTime( ServicePeriod* this, int timezone_offset, long time ) ;
 
-struct Timezone {
-    TimezonePeriod* head;
-} ; 
-
 #endif
diff --git a/core/timezone.h b/core/timezone.h
index 3b5bd53b..9d1febde 100644
--- a/core/timezone.h
+++ b/core/timezone.h
@@ -8,6 +8,10 @@ struct TimezonePeriod {
   TimezonePeriod* next_period;
 } ;
 
+struct Timezone {
+    TimezonePeriod* head;
+} ; 
+
 Timezone*
 tzNew(void);
 
diff --git a/pygs/graphserver/compiler/gdb_import_gtfs.py b/pygs/graphserver/compiler/gdb_import_gtfs.py
index 58c3e435..f91458f6 100644
--- a/pygs/graphserver/compiler/gdb_import_gtfs.py
+++ b/pygs/graphserver/compiler/gdb_import_gtfs.py
@@ -219,17 +219,15 @@ def gdb_load_gtfsdb(gdb, agency_namespace, gtfsdb, cursor, agency_id=None, maxtr
         acceptable_service_ids = None
 
     compiler = GTFSGraphCompiler( gtfsdb, agency_namespace, agency_id, reporter )
-    c = gdb.get_cursor()
     v_added = set([])
     for fromv_label, tov_label, edge in compiler.gtfsdb_to_edges( maxtrips, service_ids=acceptable_service_ids ):
         if fromv_label not in v_added:
-            gdb.add_vertex( fromv_label, c )
+            gdb.add_vertex( fromv_label, cursor )
             v_added.add(fromv_label)
         if tov_label not in v_added:
-            gdb.add_vertex( tov_label, c )
+            gdb.add_vertex( tov_label, cursor )
             v_added.add(tov_label)
-        gdb.add_edge( fromv_label, tov_label, edge, c )
-    gdb.commit()
+        gdb.add_edge( fromv_label, tov_label, edge, cursor )
 
 def graph_load_gtfsdb( agency_namespace, gtfsdb, agency_id=None, maxtrips=None, reporter=sys.stdout ):
     compiler = GTFSGraphCompiler( gtfsdb, agency_namespace, agency_id, reporter )
diff --git a/pygs/graphserver/core.py b/pygs/graphserver/core.py
index 626f64e0..76cd2b49 100644
--- a/pygs/graphserver/core.py
+++ b/pygs/graphserver/core.py
@@ -323,6 +323,8 @@ def vertices(self):
         for i in range(count.value):
             v = SPTVertex.from_pointer(arr[i])
             verts.append(v)
+	del arr
+	libc.free(p_va)
         return verts
     
     @property
@@ -1489,7 +1491,6 @@ def __repr__(self):
         return "<Crossing %s>"%list(self.get_all_crossings())
         
 class Combination(EdgePayload):
-    
     n = cproperty( lgs.comboN, c_int )
     
     def __init__(self, cap):
@@ -1506,7 +1507,7 @@ def to_xml(self):
         return "<Combination n=%d />"%self.n
         
     def __getstate__(self):
-        return [ self.get( i ).soul for i in range(self.n) ]
+        raise NotImplementedError("A Combination's state is the set of rowids of the rows storing its constituants in the graphdb, which it doesn't know.")
     
     @classmethod
     def reconstitute(cls, state, graphdb):
diff --git a/pygs/graphserver/graphdb.py b/pygs/graphserver/graphdb.py
index 62b215fd..0f5e5587 100644
--- a/pygs/graphserver/graphdb.py
+++ b/pygs/graphserver/graphdb.py
@@ -25,9 +25,9 @@ def __init__(self, sqlite_filename, overwrite=False):
         
     def setup(self):
         c = self.conn.cursor()
-        c.execute( "CREATE TABLE vertices (label)" )
-        c.execute( "CREATE TABLE payloads (id TEXT UNIQUE ON CONFLICT IGNORE, type TEXT, state TEXT)" )
-        c.execute( "CREATE TABLE edges (vertex1 TEXT, vertex2 TEXT, epid TEXT)" )
+        c.execute( "CREATE TABLE vertices (label TEXT UNIQUE ON CONFLICT IGNORE)" )
+        c.execute( "CREATE TABLE payloads (id INTEGER PRIMARY KEY, type TEXT, state TEXT)" )
+        c.execute( "CREATE TABLE edges (vertex1 TEXT, vertex2 TEXT, epid INTEGER)" )
         c.execute( "CREATE TABLE resources (name TEXT UNIQUE ON CONFLICT IGNORE, image TEXT)" )
     
         self.conn.commit()
@@ -36,12 +36,21 @@ def setup(self):
     def put_edge_payload(self, edgepayload, cc):
         
         if edgepayload.__class__ == Combination:
+	    edge_state = []
+
             for component in edgepayload.components:
-                self.put_edge_payload( component, cc )
-        
-        cc.execute( "INSERT INTO payloads VALUES (?, ?, ?)", ( str(edgepayload.soul), cPickle.dumps( edgepayload.__class__ ), cPickle.dumps( edgepayload.__getstate__() ) ) )
+                rowid = self.put_edge_payload( component, cc )
+
+		edge_state.append( rowid )
+        else:
+	    edge_state = edgepayload.__getstate__()
+
         
-        return str(edgepayload.soul)
+        cc.execute( "INSERT INTO payloads (type, state) VALUES (?, ?)", 
+	            ( cPickle.dumps( edgepayload.__class__ ), 
+		      cPickle.dumps( edge_state ) ) )
+
+	return cc.lastrowid
         
     def get_edge_payload(self, id):
         queryresult = list(self.execute( "SELECT id, type, state FROM payloads WHERE id=?", (id,) ))
@@ -70,10 +79,12 @@ def populate(self, graph, reporter=None):
             c.execute( "INSERT INTO vertices VALUES (?)", (vv.label,) )
             for ee in vv.outgoing:
                 epid = self.put_edge_payload( ee.payload, c )
+
                 c.execute( "INSERT INTO edges VALUES (?, ?, ?)", (ee.from_v.label, ee.to_v.label, epid) )
-                
+
                 if hasattr(ee.payload, "__resources__"):
                     for name, resource in ee.payload.__resources__():
+
                         self.store( name, resource, c )
         
         self.conn.commit()