feat: Add stopsWithRegularTransfers build config parameter

Introduces a new build configuration parameter
`stopsWithRegularTransfers` that allows operators to explicitly
list stop IDs for which regular transfers are always
pre-computed during graph build, even if the stop has no
scheduled trips in the static data.

This is needed for stops that are normally unused in static
GTFS/NeTEx data but may be visited at runtime via real-time
updates (e.g. a platform a train can be re-routed to). Without
this, such stops are excluded from transfer pre-computation.

The parameter is marked experimental and is intended as a
temporary workaround until automatic transfer updates based on
real-time updates are implemented.

Author: t2gran

application/src/main/java/org/opentripplanner/graph_builder/module/transfer/DirectTransferGenerator.java

@@ -11,6 +11,7 @@
 import java.util.Objects;
 import java.util.Set;
 import java.util.concurrent.atomic.AtomicInteger;
+import org.opentripplanner.core.model.id.FeedScopedId;
 import org.opentripplanner.framework.application.OTPFeature;
 import org.opentripplanner.graph_builder.issue.api.DataImportIssueStore;
 import org.opentripplanner.graph_builder.issues.StopNotLinkedForTransfers;
@@ -53,6 +54,7 @@ public class DirectTransferGenerator implements GraphBuilderModule {
 
   private final Duration defaultMaxTransferDuration;
 
+  private final Set<FeedScopedId> includeStopsWithRegularTransfers;
   private final List<RouteRequest> transferRequests;
   private final Map<StreetMode, TransferParametersForMode> transferParametersForMode;
   private final Graph graph;
@@ -61,7 +63,8 @@ public class DirectTransferGenerator implements GraphBuilderModule {
   private final DataImportIssueStore issueStore;
 
   /**
-   * Constructor used in tests. This initializes transferParametersForMode as an empty map.
+   * Constructor used in tests. This initializes transferParametersForMode as an empty map and
+   * stopsWithRegularTransfers as an empty set.
    */
   public DirectTransferGenerator(
     Graph graph,
@@ -75,6 +78,7 @@ public DirectTransferGenerator(
     this.timetableRepository = timetableRepository;
     this.issueStore = issueStore;
     this.defaultMaxTransferDuration = defaultMaxTransferDuration;
+    this.includeStopsWithRegularTransfers = Set.of();
     this.transferRequests = transferRequests;
     this.transferRepository = transferRepository;
     this.transferParametersForMode = Map.of();
@@ -91,6 +95,7 @@ public DirectTransferGenerator(
     this.timetableRepository = timetableRepository;
     this.issueStore = issueStore;
     this.defaultMaxTransferDuration = parameters.maxDuration();
+    this.includeStopsWithRegularTransfers = Set.copyOf(parameters.includeStops());
     this.transferRequests = parameters.requests();
     this.transferParametersForMode = parameters.parametersForMode();
     this.transferRepository = transferRepository;
@@ -252,7 +257,11 @@ private NearbyStopFinder createNearbyStopFinder(Duration radiusAsDuration) {
     }
 
     if (OTPFeature.ConsiderPatternsForDirectTransfers.isOn()) {
-      return new PatternConsideringNearbyStopFinder(transitService, finder);
+      return new PatternConsideringNearbyStopFinder(
+        transitService,
+        finder,
+        includeStopsWithRegularTransfers
+      );
     } else {
       return finder;
     }

application/src/main/java/org/opentripplanner/graph_builder/module/transfer/api/RegularTransferParameters.java

@@ -5,29 +5,34 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Objects;
+import org.opentripplanner.core.model.id.FeedScopedId;
 import org.opentripplanner.routing.api.request.RouteRequest;
 import org.opentripplanner.street.model.StreetMode;
 
 public final class RegularTransferParameters {
 
   private final Duration maxDuration;
+  private final List<FeedScopedId> includeStops;
   private final Map<StreetMode, TransferParametersForMode> parametersForMode;
   private final List<RouteRequest> requests;
 
   public static RegularTransferParameters DEFAULT = new RegularTransferParameters();
 
   private RegularTransferParameters() {
     this.maxDuration = Duration.ofMinutes(30);
+    this.includeStops = List.of();
     this.parametersForMode = Map.of();
     this.requests = List.of();
   }
 
   public RegularTransferParameters(
     Duration maxDuration,
+    List<FeedScopedId> includeStops,
     Map<StreetMode, TransferParametersForMode> parametersForMode,
     List<RouteRequest> requests
   ) {
     this.maxDuration = Objects.requireNonNull(maxDuration);
+    this.includeStops = List.copyOf(includeStops);
     this.parametersForMode = Map.copyOf(parametersForMode);
     this.requests = List.copyOf(requests);
   }
@@ -40,6 +45,10 @@ public Duration maxDuration() {
     return maxDuration;
   }
 
+  public List<FeedScopedId> includeStops() {
+    return includeStops;
+  }
+
   public Map<StreetMode, TransferParametersForMode> parametersForMode() {
     return parametersForMode;
   }
@@ -51,11 +60,13 @@ public List<RouteRequest> requests() {
   public static class Builder {
 
     private Duration maxDuration;
+    private List<FeedScopedId> includeStops;
     private Map<StreetMode, TransferParametersForMode> parametersForMode = new HashMap<>();
     private List<RouteRequest> requests;
 
     private Builder(RegularTransferParameters original) {
       this.maxDuration = original.maxDuration;
+      this.includeStops = original.includeStops;
       this.parametersForMode.putAll(original.parametersForMode);
       this.requests = original.requests;
     }
@@ -65,6 +76,11 @@ public Builder withMaxDuration(Duration maxDuration) {
       return this;
     }
 
+    public Builder withIncludeStops(List<FeedScopedId> includeStops) {
+      this.includeStops = includeStops;
+      return this;
+    }
+
     /// Note! This method replace/overwrite any existing content
     public Builder withParametersForMode(Map<StreetMode, TransferParametersForMode> map) {
       this.parametersForMode.clear();
@@ -84,7 +100,7 @@ public Builder withRequests(List<RouteRequest> requests) {
     }
 
     public RegularTransferParameters build() {
-      return new RegularTransferParameters(maxDuration, parametersForMode, requests);
+      return new RegularTransferParameters(maxDuration, includeStops, parametersForMode, requests);
     }
   }
 }

application/src/main/java/org/opentripplanner/graph_builder/module/transfer/filter/PatternConsideringNearbyStopFinder.java

@@ -2,6 +2,8 @@
 
 import java.util.Collection;
 import java.util.List;
+import java.util.Set;
+import org.opentripplanner.core.model.id.FeedScopedId;
 import org.opentripplanner.framework.application.OTPFeature;
 import org.opentripplanner.graph_builder.module.nearbystops.NearbyStopFinder;
 import org.opentripplanner.routing.api.request.RouteRequest;
@@ -34,9 +36,12 @@ public class PatternConsideringNearbyStopFinder implements NearbyStopFinder {
 
   public PatternConsideringNearbyStopFinder(
     TransitService transitService,
-    NearbyStopFinder delegateNearbyStopFinder
+    NearbyStopFinder delegateNearbyStopFinder,
+    Set<FeedScopedId> stopsWithRegularTransfers
   ) {
-    var builder = CompositeNearbyStopFilter.of().add(new PatternNearbyStopFilter(transitService));
+    var builder = CompositeNearbyStopFilter.of().add(
+      new PatternNearbyStopFilter(transitService, stopsWithRegularTransfers)
+    );
 
     if (OTPFeature.FlexRouting.isOn()) {
       builder.add(new FlexTripNearbyStopFilter(transitService));

application/src/main/java/org/opentripplanner/graph_builder/module/transfer/filter/PatternNearbyStopFilter.java

@@ -20,14 +20,20 @@
  * or alighting is possible (depending on direction).
  * <p>
  * Stops without patterns may still be included if they are marked as sometimes-used by real-time
- * updates (when the IncludeStopsUsedRealTimeInTransfers feature is enabled).
+ * updates (when the IncludeStopsUsedRealTimeInTransfers feature is enabled), or if they are
+ * explicitly listed in the {@code stopsWithRegularTransfers} build configuration.
  */
 class PatternNearbyStopFilter implements NearbyStopFilter {
 
   private final TransitService transitService;
+  private final Set<FeedScopedId> stopsWithRegularTransfers;
 
-  PatternNearbyStopFilter(TransitService transitService) {
+  PatternNearbyStopFilter(
+    TransitService transitService,
+    Set<FeedScopedId> stopsWithRegularTransfers
+  ) {
     this.transitService = transitService;
+    this.stopsWithRegularTransfers = stopsWithRegularTransfers;
   }
 
   @Override
@@ -82,6 +88,15 @@ private List<FeedScopedId> findPatternsForStop(RegularStop stop, boolean reverse
   }
 
   private boolean includeStopUsedRealtime(RegularStop stop) {
-    return OTPFeature.IncludeStopsUsedRealTimeInTransfers.isOn() && stop.isSometimesUsedRealtime();
+    // Some stops, like railway and bus-replacement stops, are tagged during graph building/data
+    // import. These should allways be included.
+    if (OTPFeature.IncludeStopsUsedRealTimeInTransfers.isOn() && stop.isSometimesUsedRealtime()) {
+      return true;
+    }
+    // Some stops is listed in the build-config, these are regular stops to include.
+    if (stopsWithRegularTransfers.contains(stop.getId())) {
+      return true;
+    }
+    return false;
   }
 }

application/src/main/java/org/opentripplanner/standalone/config/buildconfig/RegularTransferConfig.java

@@ -30,6 +30,32 @@ public static RegularTransferParameters map(NodeAdapter root) {
         .asDuration(dft.maxDuration())
     );
 
+    builder.withIncludeStops(
+      root
+        .of("stopsWithRegularTransfers")
+        .since(V2_9)
+        .summary(
+          "Stops that should always have regular transfers computed, even without scheduled trips."
+        )
+        .description(
+          """
+          List of stop IDs for which regular transfers are always pre-computed during graph build,
+          even if the stop has no scheduled trips. Remember to include _feedId_ like this
+          `"RB:NSR:Quay:102541"`.
+
+          This is useful for stops that are unused in static transit data, but may be visited by
+          real-time updates (e.g. a platform that a train can be re-routed to at runtime). Without
+          this configuration, stops with no scheduled trips are excluded from transfer pre-computation
+          and become unreachable islands when a real-time update routes a trip to them.
+
+          Note! This parameter should be replaced with an automatic update to regular transfers
+          based on real-time updates.
+          """
+        )
+        .experimentalFeature()
+        .asFeedScopedIds(List.of())
+    );
+
     builder.withParametersForMode(
       root
         .of("transferParametersForMode")

doc/user/BuildConfiguration.md

@@ -93,6 +93,7 @@ Sections follow that describe particular settings in more depth.
 |    includeOsmSubwayEntrances                                                                |       `boolean`      | Whether to include subway entrances from the OSM data.                                                                                                         | *Optional* | `false`                           |  2.7  |
 |    [osmTagMapping](#od_osmTagMapping)                                                       |        `enum`        | The named set of mapping rules applied when parsing OSM tags.                                                                                                  | *Optional* | `"default"`                       |  2.2  |
 |    timeZone                                                                                 |      `time-zone`     | The timezone used to resolve opening hours in OSM data.                                                                                                        | *Optional* |                                   |  2.2  |
+| [stopsWithRegularTransfers](#stopsWithRegularTransfers)                                     |  `feed-scoped-id[]`  | Stops that should always have regular transfers computed, even without scheduled trips.                                                                        | *Optional* |                                   |  2.9  |
 | [transferParametersForMode](#transferParametersForMode)                                     | `enum map of object` | Configures mode-specific properties for transfer calculations.                                                                                                 | *Optional* |                                   |  2.7  |
 |    BIKE                                                                                     |       `object`       | NA                                                                                                                                                             | *Optional* |                                   |  2.7  |
 |       [bikesAllowedStopMaxTransferDuration](#tpfm_BIKE_bikesAllowedStopMaxTransferDuration) |      `duration`      | This is used for specifying a `maxTransferDuration` value to use with transfers between stops which are visited by trips that allow bikes.                     | *Optional* |                                   |  2.9  |
@@ -950,6 +951,28 @@ The named set of mapping rules applied when parsing OSM tags. Overrides the valu
 
 The named set of mapping rules applied when parsing OSM tags.
 
+<h3 id="stopsWithRegularTransfers">stopsWithRegularTransfers</h3>
+
+**Since version:** `2.9` ∙ **Type:** `feed-scoped-id[]` ∙ **Cardinality:** `Optional`   
+**Path:** / 
+
+Stops that should always have regular transfers computed, even without scheduled trips.
+
+List of stop IDs for which regular transfers are always pre-computed during graph build,
+even if the stop has no scheduled trips. Remember to include _feedId_ like this
+`"RB:NSR:Quay:102541"`.
+
+This is useful for stops that are unused in static transit data, but may be visited by
+real-time updates (e.g. a platform that a train can be re-routed to at runtime). Without
+this configuration, stops with no scheduled trips are excluded from transfer pre-computation
+and become unreachable islands when a real-time update routes a trip to them.
+
+Note! This parameter should be replaced with an automatic update to regular transfers
+based on real-time updates.
+
+
+**THIS IS STILL AN EXPERIMENTAL FEATURE - IT MAY CHANGE WITHOUT ANY NOTICE!**
+
 <h3 id="transferParametersForMode">transferParametersForMode</h3>
 
 **Since version:** `2.7` ∙ **Type:** `enum map of object` ∙ **Cardinality:** `Optional`