diff --git a/liberty/EquivCells.cc b/liberty/EquivCells.cc
index 953202ee..6afca9c9 100644
--- a/liberty/EquivCells.cc
+++ b/liberty/EquivCells.cc
@@ -29,6 +29,8 @@
 
 namespace sta {
 
+using std::max;
+
 typedef UnorderedMap<unsigned, LibertyCellSeq*> LibertyCellHashMap;
 typedef Set<LibertyCell*> LibertyCellSet;
 
@@ -116,6 +118,13 @@ struct CellDriveResistanceLess
   }
 };
 
+static float
+cellDriveResistance(const LibertyCell *cell)
+{
+  return max(cell->driveResistance(TransRiseFall::rise()),
+	     cell->driveResistance(TransRiseFall::fall()));
+}
+
 static void
 sortCellEquivs(LibertyCellSet &cell_equivs)
 {
@@ -135,30 +144,6 @@ sortCellEquivs(LibertyCellSet &cell_equivs)
   }
 }
 
-// Use the worst "drive" for all the timing arcs in the cell.
-static float
-cellDriveResistance(const LibertyCell *cell)
-{
-  float max_drive = 0.0;
-  LibertyCellTimingArcSetIterator set_iter(cell);
-  while (set_iter.hasNext()) {
-    TimingArcSet *set = set_iter.next();
-    if (!set->role()->isTimingCheck()) {
-      TimingArcSetArcIterator arc_iter(set);
-      while (arc_iter.hasNext()) {
-	TimingArc *arc = arc_iter.next();
-	GateTimingModel *model = dynamic_cast<GateTimingModel*>(arc->model());
-	if (model) {
-	  float drive = model->driveResistance(cell, nullptr);
-	  if (drive > max_drive)
-	    max_drive = drive;
-	}
-      }
-    }
-  }
-  return max_drive;
-}
-
 static unsigned
 hashCell(const LibertyCell *cell)
 {
diff --git a/liberty/Liberty.cc b/liberty/Liberty.cc
index 9d0a289f..7a3f03d2 100644
--- a/liberty/Liberty.cc
+++ b/liberty/Liberty.cc
@@ -1477,6 +1477,30 @@ LibertyCell::setEquivCells(LibertyCellSeq *equiv_cells)
   equiv_cells_ = equiv_cells;
 }
 
+// Use the worst "drive" for all the timing arcs in the cell.
+float
+LibertyCell::driveResistance(const TransRiseFall *tr) const
+{
+  float max_drive = 0.0;
+  LibertyCellTimingArcSetIterator set_iter(this);
+  while (set_iter.hasNext()) {
+    TimingArcSet *set = set_iter.next();
+    if (!set->role()->isTimingCheck()) {
+      TimingArcSetArcIterator arc_iter(set);
+      while (arc_iter.hasNext()) {
+	TimingArc *arc = arc_iter.next();
+	GateTimingModel *model = dynamic_cast<GateTimingModel*>(arc->model());
+	if (model) {
+	  float drive = model->driveResistance(this, nullptr);
+	  if (drive > max_drive)
+	    max_drive = drive;
+	}
+      }
+    }
+  }
+  return max_drive;
+}
+
 LibertyCell *
 LibertyCell::higherDrive() const
 {
diff --git a/liberty/Liberty.hh b/liberty/Liberty.hh
index 9d1c8a91..f1809fc1 100644
--- a/liberty/Liberty.hh
+++ b/liberty/Liberty.hh
@@ -496,6 +496,7 @@ public:
   // Internal.
   LibertyCellSeq *equivCellsRaw() { return equiv_cells_; }
   void setEquivCells(LibertyCellSeq *equiv_cells);
+  float driveResistance(const TransRiseFall *tr) const;
   void setHigherDrive(LibertyCell *cell);
   void setLowerDrive(LibertyCell *cell);
   bool isBuffer() const;
diff --git a/search/Property.cc b/search/Property.cc
index b90e0941..7598298d 100644
--- a/search/Property.cc
+++ b/search/Property.cc
@@ -527,12 +527,18 @@ getProperty(const LibertyCell *cell,
     return PropertyValue(cell->filename());
   else if (stringEqual(property, "library"))
     return PropertyValue(cell->libertyLibrary());
+  else if (stringEqual(property, "drive_resistance_rise"))
+    return PropertyValue(cell->driveResistance(TransRiseFall::rise()));
+  else if (stringEqual(property, "drive_resistance_fall"))
+    return PropertyValue(cell->driveResistance(TransRiseFall::fall()));
   else if (stringEqual(property, "higher_drive"))
     return PropertyValue(cell->higherDrive());
   else if (stringEqual(property, "lower_drive"))
     return PropertyValue(cell->lowerDrive());
   else if (stringEqual(property, "is_buffer"))
     return PropertyValue(cell->isBuffer());
+  else if (stringEqual(property, "dont_use"))
+    return PropertyValue(cell->dontUse());
   else
     throw PropertyUnknown("liberty cell", property);
 }