diff --git a/src/main/java/org/mtransit/parser/DefaultAgencyTools.java b/src/main/java/org/mtransit/parser/DefaultAgencyTools.java
index b23120d..923dd69 100644
--- a/src/main/java/org/mtransit/parser/DefaultAgencyTools.java
+++ b/src/main/java/org/mtransit/parser/DefaultAgencyTools.java
@@ -966,13 +966,22 @@ public void forgetOriginalTripId(@NotNull String gOriginalTripId) {
 		this.tripIdToCleanupTripId.remove(gOriginalTripId);
 	}
 
+	private boolean directionSplitterUseful = false; // opt-in feature
+
 	@Override
-	public boolean directionSplitterEnabled() {
-		return Configs.getRouteConfig().isDirectionSplitterEnabled(getTodayDateInt());
+	public void setDirectionSplitterUseful(boolean enabled) {
+		this.directionSplitterUseful = enabled;
 	}
 
 	@Override
 	public boolean directionSplitterEnabled(long routeId) {
+		if (Configs.getRouteConfig().getDirectionSplitterEnabled() == null // not set
+				&& !Configs.getRouteConfig().getDirectionSplitterDisabledUntil().containsKey(routeId) // not disabled for this route
+		) {
+			if (this.directionSplitterUseful) {
+				return true;
+			}
+		}
 		return Configs.getRouteConfig().isDirectionSplitterEnabled(getTodayDateInt(), routeId);
 	}
 
diff --git a/src/main/java/org/mtransit/parser/config/gtfs/data/RouteConfig.kt b/src/main/java/org/mtransit/parser/config/gtfs/data/RouteConfig.kt
index 5263b90..6fbb04f 100644
--- a/src/main/java/org/mtransit/parser/config/gtfs/data/RouteConfig.kt
+++ b/src/main/java/org/mtransit/parser/config/gtfs/data/RouteConfig.kt
@@ -99,7 +99,7 @@ data class RouteConfig(
     @SerialName("direction_headsign_ignore_trip_headsign")
     val directionHeadsignIgnoreTripHeadsign: Boolean = false, // OPT-IN feature
     @SerialName("direction_splitter_enabled")
-    val directionSplitterEnabled: Boolean = false, // OPT-IN feature
+    val directionSplitterEnabled: Boolean? = null, // OPT-IN feature
     @SerialName("direction_splitter_disabled_until")
     val directionSplitterDisabledUntil: Map<Long, String> = emptyMap(), // OPT-IN feature
     @SerialName("direction_finder_enabled")
@@ -475,7 +475,7 @@ data class RouteConfig(
 
     @JvmOverloads
     fun isDirectionSplitterEnabled(todayDate: Int, routeId: Long? = null) =
-        directionSplitterEnabled && !isAllowedUntil(directionSplitterDisabledUntil[routeId], todayDate)
+        directionSplitterEnabled == true && !isAllowedUntil(directionSplitterDisabledUntil[routeId], todayDate)
 
     fun isDirectionIdOverrideEnabled(todayDate: Int, routeId: Long) =
         directionIdOverrideEnabled[routeId] == true || isAllowedUntil(directionIdOverrideEnabledUntil[routeId], todayDate)
diff --git a/src/main/java/org/mtransit/parser/gtfs/GAgencyTools.java b/src/main/java/org/mtransit/parser/gtfs/GAgencyTools.java
index d24a5c9..db0a7b5 100644
--- a/src/main/java/org/mtransit/parser/gtfs/GAgencyTools.java
+++ b/src/main/java/org/mtransit/parser/gtfs/GAgencyTools.java
@@ -202,7 +202,7 @@ public interface GAgencyTools {
 
 	void forgetOriginalTripId(@NotNull String gTripOriginalId);
 
-	boolean directionSplitterEnabled();
+	void setDirectionSplitterUseful(boolean enabled);
 
 	boolean directionSplitterEnabled(long routeId);
 
diff --git a/src/main/java/org/mtransit/parser/gtfs/GReader.java b/src/main/java/org/mtransit/parser/gtfs/GReader.java
index a085c0e..c00953d 100644
--- a/src/main/java/org/mtransit/parser/gtfs/GReader.java
+++ b/src/main/java/org/mtransit/parser/gtfs/GReader.java
@@ -106,8 +106,13 @@ public static GSpec readGtfsZipFile(
 			if (!calendarsOnly) {
 				GTFSDataBase.setAutoCommit(false);
 				final PreparedStatement insertTripsPrepared = USE_PREPARED_STATEMENT ? GTFSDataBase.prepareInsertTrip(agencyTools.allowDuplicateKeyError()) : null;
-				readFile(gtfsDir, GTrip.FILENAME, true, line ->
-						processTrip(agencyTools, gSpec, line, insertTripsPrepared, skipDataCleanup)
+				readFile(gtfsDir, GTrip.FILENAME, true,
+						line -> processTrip(agencyTools, gSpec, line, insertTripsPrepared, skipDataCleanup),
+						columnNames -> {
+							if (!columnNames.contains(GTrip.DIRECTION_ID)) {
+								agencyTools.setDirectionSplitterUseful(true); // direction IDs not provided
+							}
+						}
 				);
 				if (insertTripsPrepared != null) {
 					GTFSDataBase.executePreparedStatement(insertTripsPrepared);
diff --git a/src/main/java/org/mtransit/parser/gtfs/data/GTrip.kt b/src/main/java/org/mtransit/parser/gtfs/data/GTrip.kt
index 9fdd85b..9cd08bc 100644
--- a/src/main/java/org/mtransit/parser/gtfs/data/GTrip.kt
+++ b/src/main/java/org/mtransit/parser/gtfs/data/GTrip.kt
@@ -136,7 +136,7 @@ data class GTrip(
         internal const val SERVICE_ID = "service_id"
         private const val TRIP_HEADSIGN = "trip_headsign"
         private const val TRIP_SHORT_NAME = "trip_short_name"
-        private const val DIRECTION_ID = "direction_id"
+        internal const val DIRECTION_ID = "direction_id"
         private const val BLOCK_ID = "block_id"
         private const val SHAPE_ID = "shape_id"
         private const val WHEELCHAIR_ACCESSIBLE = "wheelchair_accessible"