diff --git a/images/tiler-server/config/providers/transport_lines.toml b/images/tiler-server/config/providers/transport_lines.toml
index bd481324..a4c1ee9a 100644
--- a/images/tiler-server/config/providers/transport_lines.toml
+++ b/images/tiler-server/config/providers/transport_lines.toml
@@ -7,15 +7,15 @@ sql = """
 SELECT 
     ST_AsMVTGeom(geometry, !BBOX!) AS geometry, 
     ABS(osm_id) AS osm_id, 
-    NULLIF(type, '') AS type, 
-    NULLIF(tunnel, '') AS tunnel, 
-    NULLIF(bridge, '') AS bridge, 
-    NULLIF(ref, '') AS ref,
-    NULLIF(service, '') AS service,
-    NULLIF(name, '') AS name,
-    NULLIF(electrified, '') AS electrified, 
-    NULLIF(highspeed, '') AS highspeed, 
-    NULLIF(usage, '') AS usage, 
+    type, 
+    tunnel, 
+    bridge, 
+    ref,
+    service,
+    name,
+    electrified, 
+    highspeed, 
+    usage, 
     NULLIF(start_date, '') AS start_date, 
     NULLIF(end_date, '') AS end_date, 
     isodatetodecimaldate(pad_date(start_date, 'start'), FALSE) AS start_decdate, 
@@ -36,14 +36,16 @@ sql = """
 SELECT 
     ST_AsMVTGeom(geometry, !BBOX!) AS geometry, 
     ABS(osm_id) AS osm_id,
-    NULLIF(ref, '') AS ref, 
-    NULLIF(class, '') AS class, 
-    NULLIF(type, '') AS type, 
-    NULLIF(service, '') AS service,
-    NULLIF(name, '') AS name,
-    NULLIF(electrified, '') AS electrified, 
-    NULLIF(highspeed, '') AS highspeed, 
-    NULLIF(usage, '') AS usage, 
+    ref, 
+    class, 
+    type, 
+    tunnel, 
+    bridge, 
+    service,
+    name,
+    electrified, 
+    highspeed, 
+    usage, 
     NULLIF(start_date, '') AS start_date, 
     NULLIF(end_date, '') AS end_date, 
     isodatetodecimaldate(pad_date(start_date, 'start'), FALSE) AS start_decdate, 
@@ -64,14 +66,16 @@ sql = """
 SELECT 
     ST_AsMVTGeom(geometry, !BBOX!) AS geometry, 
     ABS(osm_id) AS osm_id, 
-    NULLIF(ref, '') AS ref, 
-    NULLIF(class, '') AS class, 
-    NULLIF(type, '') AS type, 
-    NULLIF(service, '') AS service, 
-    NULLIF(name, '') AS name,
-    NULLIF(electrified, '') AS electrified, 
-    NULLIF(highspeed, '') AS highspeed, 
-    NULLIF(usage, '') AS usage, 
+    ref, 
+    class, 
+    type, 
+    tunnel, 
+    bridge, 
+    service, 
+    name,
+    electrified, 
+    highspeed, 
+    usage, 
     NULLIF(start_date, '') AS start_date, 
     NULLIF(end_date, '') AS end_date, 
     isodatetodecimaldate(pad_date(start_date, 'start'), FALSE) AS start_decdate, 
@@ -92,14 +96,16 @@ sql = """
 SELECT 
     ST_AsMVTGeom(geometry, !BBOX!) AS geometry, 
     ABS(osm_id) AS osm_id, 
-    NULLIF(ref, '') AS ref, 
-    NULLIF(class, '') AS class, 
-    NULLIF(type, '') AS type, 
-    NULLIF(service, '') AS service, 
-    NULLIF(name, '') AS name,
-    NULLIF(electrified, '') AS electrified, 
-    NULLIF(highspeed, '') AS highspeed, 
-    NULLIF(usage, '') AS usage, 
+    ref, 
+    class, 
+    tunnel, 
+    bridge, 
+    type, 
+    service, 
+    name,
+    electrified, 
+    highspeed, 
+    usage, 
     NULLIF(start_date, '') AS start_date, 
     NULLIF(end_date, '') AS end_date, 
     isodatetodecimaldate(pad_date(start_date, 'start'), FALSE) AS start_decdate, 
@@ -120,14 +126,16 @@ sql = """
 SELECT 
     ST_AsMVTGeom(geometry, !BBOX!) AS geometry, 
     ABS(osm_id) AS osm_id,  
-    NULLIF(ref, '') AS ref, 
-    NULLIF(class, '') AS class, 
-    NULLIF(type, '') AS type, 
-    NULLIF(service, '') AS service, 
-    NULLIF(name, '') AS name,
-    NULLIF(electrified, '') AS electrified, 
-    NULLIF(highspeed, '') AS highspeed, 
-    NULLIF(usage, '') AS usage, 
+    ref, 
+    class, 
+    type, 
+    tunnel, 
+    bridge, 
+    service, 
+    name,
+    electrified, 
+    highspeed, 
+    usage, 
     NULLIF(start_date, '') AS start_date, 
     NULLIF(end_date, '') AS end_date, 
     isodatetodecimaldate(pad_date(start_date, 'start'), FALSE) AS start_decdate,