diff --git a/java-spanner/google-cloud-spanner/src/test/java/com/google/cloud/spanner/LocationAwareSharedBackendReplicaHarnessTest.java b/java-spanner/google-cloud-spanner/src/test/java/com/google/cloud/spanner/LocationAwareSharedBackendReplicaHarnessTest.java
index d55e95653e21..3e0924591cb1 100644
--- a/java-spanner/google-cloud-spanner/src/test/java/com/google/cloud/spanner/LocationAwareSharedBackendReplicaHarnessTest.java
+++ b/java-spanner/google-cloud-spanner/src/test/java/com/google/cloud/spanner/LocationAwareSharedBackendReplicaHarnessTest.java
@@ -16,6 +16,7 @@
 
 package com.google.cloud.spanner;
 
+import static org.awaitility.Awaitility.await;
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertNotEquals;
 import static org.junit.Assert.assertTrue;
@@ -49,6 +50,7 @@
 import io.grpc.Status;
 import io.grpc.StatusRuntimeException;
 import io.grpc.protobuf.ProtoUtils;
+import java.time.Duration;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
@@ -573,8 +575,13 @@ private static boolean drain(ResultSet resultSet) {
     return sawRow;
   }
 
+  private static void waitForAllReplicasConnected(SharedBackendReplicaHarness harness) {
+    await().atMost(Duration.ofSeconds(10)).until(harness::allReplicasConnected);
+  }
+
   private static int waitForReplicaRoutedRead(
       DatabaseClient client, SharedBackendReplicaHarness harness) throws InterruptedException {
+    waitForAllReplicasConnected(harness);
     long deadlineNanos = System.nanoTime() + TimeUnit.SECONDS.toNanos(10);
     while (System.nanoTime() < deadlineNanos) {
       try (ResultSet resultSet =
diff --git a/java-spanner/google-cloud-spanner/src/test/java/com/google/cloud/spanner/SharedBackendReplicaHarness.java b/java-spanner/google-cloud-spanner/src/test/java/com/google/cloud/spanner/SharedBackendReplicaHarness.java
index 7aa5eb88c3e0..7395a55d44fd 100644
--- a/java-spanner/google-cloud-spanner/src/test/java/com/google/cloud/spanner/SharedBackendReplicaHarness.java
+++ b/java-spanner/google-cloud-spanner/src/test/java/com/google/cloud/spanner/SharedBackendReplicaHarness.java
@@ -34,12 +34,14 @@
 import com.google.spanner.v1.Session;
 import com.google.spanner.v1.SpannerGrpc;
 import com.google.spanner.v1.Transaction;
+import io.grpc.Attributes;
 import io.grpc.Metadata;
 import io.grpc.Server;
 import io.grpc.ServerCall;
 import io.grpc.ServerCallHandler;
 import io.grpc.ServerInterceptor;
 import io.grpc.ServerInterceptors;
+import io.grpc.ServerTransportFilter;
 import io.grpc.netty.shaded.io.grpc.netty.NettyServerBuilder;
 import io.grpc.stub.StreamObserver;
 import java.io.Closeable;
@@ -50,6 +52,7 @@
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
+import java.util.concurrent.atomic.AtomicInteger;
 
 /** Shared-backend replica harness for end-to-end location-aware routing tests. */
 final class SharedBackendReplicaHarness implements Closeable {
@@ -71,11 +74,24 @@ static final class HookedReplicaSpannerService extends SpannerGrpc.SpannerImplBa
     private final Map<String, ArrayDeque<Throwable>> methodErrors = new HashMap<>();
     private final Map<String, List<AbstractMessage>> requests = new HashMap<>();
     private final Map<String, List<String>> requestIds = new HashMap<>();
+    private final AtomicInteger activeConnections = new AtomicInteger();
 
     private HookedReplicaSpannerService(MockSpannerServiceImpl backend) {
       this.backend = backend;
     }
 
+    void recordConnectionReady() {
+      activeConnections.incrementAndGet();
+    }
+
+    void recordConnectionTerminated() {
+      activeConnections.decrementAndGet();
+    }
+
+    boolean hasConnected() {
+      return activeConnections.get() > 0;
+    }
+
     synchronized void putMethodErrors(String method, Throwable... errors) {
       ArrayDeque<Throwable> queue = new ArrayDeque<>();
       for (Throwable error : errors) {
@@ -278,12 +294,35 @@ public <ReqT, RespT> ServerCall.Listener<ReqT> interceptCall(
     Server server =
         NettyServerBuilder.forAddress(address)
             .addService(ServerInterceptors.intercept(service, interceptor))
+            .addTransportFilter(
+                new ServerTransportFilter() {
+                  @Override
+                  public Attributes transportReady(Attributes transportAttrs) {
+                    service.recordConnectionReady();
+                    return super.transportReady(transportAttrs);
+                  }
+
+                  @Override
+                  public void transportTerminated(Attributes transportAttrs) {
+                    service.recordConnectionTerminated();
+                    super.transportTerminated(transportAttrs);
+                  }
+                })
             .build()
             .start();
     servers.add(server);
     return "localhost:" + server.getPort();
   }
 
+  boolean allReplicasConnected() {
+    for (HookedReplicaSpannerService replica : replicas) {
+      if (!replica.hasConnected()) {
+        return false;
+      }
+    }
+    return true;
+  }
+
   void clearRequests() {
     defaultReplica.clearRequests();
     for (HookedReplicaSpannerService replica : replicas) {