--- a/rail_cmd.c	Tue Nov 07 18:42:31 2006 +0000
+++ b/rail_cmd.c	Tue Nov 07 22:34:59 2006 +0000
@@ -273,7 +273,7 @@
 				return CMD_ERROR;
 			}
 			if (!IsTileOwner(tile, _current_player) ||
-					GetRailType(tile) != p1) {
+					!IsCompatibleRail(GetRailType(tile), p1)) {
 				// Get detailed error message
 				return DoCommand(tile, 0, 0, flags, CMD_LANDSCAPE_CLEAR);
 			}
@@ -282,6 +282,15 @@
 			if (CmdFailed(ret)) return ret;
 			cost += ret;
 
+			/* XXX Assume a 'higher' railtype has preference. This means we
+			 * will convert from normal rail to electrified rail, but not
+			 * the other way around. */
+			if (GetRailType(tile) < p1) {
+				ret = DoCommand(tile, tile, p1, flags, CMD_CONVERT_RAIL);
+				if (CmdFailed(ret)) return ret;
+				cost += ret;
+			}
+
 			if (flags & DC_EXEC) {
 				SetRailGroundType(tile, RAIL_GROUND_BARREN);
 				_m[tile].m5 |= trackbit;