diff --git a/.github/workflows/maven.yml b/.github/workflows/maven.yml
index 9df74c73..1904de23 100644
--- a/.github/workflows/maven.yml
+++ b/.github/workflows/maven.yml
@@ -17,10 +17,10 @@ jobs:
     steps:
       - name: Checkout this PR planetiler-openmaptiles repo
         uses: actions/checkout@v4
-      - name: Set up JDK 17
+      - name: Set up JDK 21
         uses: actions/setup-java@v3
         with:
-          java-version: 17
+          java-version: 21
           distribution: 'temurin'
           cache: 'maven'
       - name: Ensure code formatted with mvn spotless:apply
@@ -33,12 +33,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ ubuntu-latest, macos-latest, windows-latest ]
-        jdk: [ 17 ]
-        include:
-          - os: ubuntu-latest
-            jdk: 18
-          - os: ubuntu-latest
-            jdk: 19
+        jdk: [ 21 ]
     runs-on: ${{ matrix.os }}
     timeout-minutes: 15
     steps:
@@ -66,10 +61,10 @@ jobs:
     steps:
       - name: Checkout this PR planetiler-openmaptiles repo
         uses: actions/checkout@v4
-      - name: Set up JDK 17
+      - name: Set up JDK 21
         uses: actions/setup-java@v3
         with:
-          java-version: 17
+          java-version: 21
           distribution: 'temurin'
           cache: 'maven'
       - run: ./scripts/regenerate-openmaptiles.sh
@@ -88,7 +83,7 @@ jobs:
       - name: Set up JDK
         uses: actions/setup-java@v3
         with:
-          java-version: 17
+          java-version: 21
           distribution: 'temurin'
           cache: 'maven'
       - name: Build this branch
@@ -127,7 +122,7 @@ jobs:
       - name: Set up JDK
         uses: actions/setup-java@v3
         with:
-          java-version: 17
+          java-version: 21
           distribution: 'temurin'
           cache: 'maven'
       - name: Build and test this branch
diff --git a/.github/workflows/performance.yml b/.github/workflows/performance.yml
index ca9bcc7a..eb6d8b37 100644
--- a/.github/workflows/performance.yml
+++ b/.github/workflows/performance.yml
@@ -23,7 +23,7 @@ jobs:
     continue-on-error: true
     steps:
       - name: 'Cancel previous runs'
-        uses: styfle/cancel-workflow-action@0.11.0
+        uses: styfle/cancel-workflow-action@0.12.0
         with:
           access_token: ${{ github.token }}
 
@@ -45,10 +45,10 @@ jobs:
       - name: 'Set up JDK'
         uses: actions/setup-java@v3
         with:
-          java-version: 17
+          java-version: 21
           distribution: 'temurin'
           cache: 'maven'
-      - uses: actions/setup-node@v3
+      - uses: actions/setup-node@v4
         with:
           node-version: '14'
       - run: npm install -g strip-ansi-cli@3.0.2
diff --git a/.github/workflows/snapshot.yml b/.github/workflows/snapshot.yml
index 227d8e1d..4fe12506 100644
--- a/.github/workflows/snapshot.yml
+++ b/.github/workflows/snapshot.yml
@@ -14,7 +14,7 @@ jobs:
       - name: Set up JDK
         uses: actions/setup-java@v3
         with:
-          java-version: 17
+          java-version: 21
           distribution: 'temurin'
           cache: 'maven'
       - name: Login to Docker Hub
diff --git a/README.md b/README.md
index 6f383863..90ae11ff 100644
--- a/README.md
+++ b/README.md
@@ -11,7 +11,7 @@ Using pre-built docker image:
 docker run -v "$(pwd)/data":/data openmaptiles/planetiler-openmaptiles:latest --force --download --area=monaco
 ```
 
-Or to build from source, after [installing Java 17+](https://adoptium.net/installation.html):
+Or to build from source, after [installing Java 21+](https://adoptium.net/installation.html):
 
 ```bash
 # Build the project (use mvnw.cmd on windows):
diff --git a/pom.xml b/pom.xml
index b6e6f104..122b41e6 100644
--- a/pom.xml
+++ b/pom.xml
@@ -7,9 +7,9 @@
 
   <properties>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-    <maven.compiler.source>17</maven.compiler.source>
-    <maven.compiler.target>17</maven.compiler.target>
-    <planetiler.version>0.6-SNAPSHOT</planetiler.version>
+    <maven.compiler.source>21</maven.compiler.source>
+    <maven.compiler.target>21</maven.compiler.target>
+    <planetiler.version>0.7-SNAPSHOT</planetiler.version>
     <junit.version>5.10.0</junit.version>
 
     <mainClass>org.openmaptiles.OpenMapTilesMain</mainClass>
@@ -99,18 +99,18 @@
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-surefire-plugin</artifactId>
-        <version>3.1.2</version>
+        <version>3.2.1</version>
       </plugin>
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-failsafe-plugin</artifactId>
-        <version>3.1.2</version>
+        <version>3.2.1</version>
       </plugin>
 
       <plugin>
         <groupId>com.diffplug.spotless</groupId>
         <artifactId>spotless-maven-plugin</artifactId>
-        <version>2.38.0</version>
+        <version>2.40.0</version>
         <configuration>
           <java>
             <importOrder/>
@@ -140,7 +140,7 @@
         </executions>
       </plugin>
 
-      <!-- require building with jdk 17 -->
+      <!-- require building with jdk 21 -->
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-enforcer-plugin</artifactId>
@@ -154,7 +154,7 @@
             <configuration>
               <rules>
                 <requireJavaVersion>
-                  <version>17</version>
+                  <version>21</version>
                 </requireJavaVersion>
               </rules>
             </configuration>
@@ -209,7 +209,7 @@
         <configuration>
           <from>
             <image>
-              eclipse-temurin:17-jre
+              eclipse-temurin:21-jre
             </image>
             <platforms>
               <platform>
diff --git a/src/main/java/org/openmaptiles/layers/TransportationName.java b/src/main/java/org/openmaptiles/layers/TransportationName.java
index 25d19f8c..9ee452e6 100644
--- a/src/main/java/org/openmaptiles/layers/TransportationName.java
+++ b/src/main/java/org/openmaptiles/layers/TransportationName.java
@@ -57,8 +57,10 @@ OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 import com.onthegomap.planetiler.util.ZoomFunction;
 import java.util.Arrays;
 import java.util.HashMap;
+import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
+import java.util.Set;
 import java.util.function.Function;
 import org.openmaptiles.OpenMapTilesProfile;
 import org.openmaptiles.generated.OpenMapTilesSchema;
@@ -111,14 +113,6 @@ public class TransportationName implements
     .put(9, 8_000)
     .put(10, 8_000)
     .put(11, 8_000);
-  private static final List<String> CONCURRENT_ROUTE_KEYS = List.of(
-    Fields.ROUTE_1,
-    Fields.ROUTE_2,
-    Fields.ROUTE_3,
-    Fields.ROUTE_4,
-    Fields.ROUTE_5,
-    Fields.ROUTE_6
-  );
   private final boolean brunnel;
   private final boolean sizeForShield;
   private final boolean limitMerge;
@@ -273,14 +267,13 @@ public void process(Tables.OsmHighwayLinestring element, FeatureCollector featur
       .setSortKey(element.zOrder())
       .setMinZoom(minzoom);
 
-    // populate route_1, route_2, ... tags; take only unique ones
-    Object[] routes = relations.stream()
-      .map(r -> r.network() == null ? null : r.network() + "=" + coalesce(r.ref(), ""))
-      .distinct()
-      .limit(CONCURRENT_ROUTE_KEYS.size())
-      .toArray();
-    for (int i = 0; i < routes.length; i++) {
-      feature.setAttr(CONCURRENT_ROUTE_KEYS.get(i), routes[i]);
+    // populate route_1, route_2, ... route_n tags and remove duplicates
+    Set<String> routes = new HashSet<>();
+    for (var route : relations) {
+      String routeString = route.network() + "=" + coalesce(route.ref(), "");
+      if (routes.add(routeString)) {
+        feature.setAttr("route_" + routes.size(), routeString);
+      }
     }
 
     if (brunnel) {
diff --git a/src/test/java/org/openmaptiles/layers/TransportationTest.java b/src/test/java/org/openmaptiles/layers/TransportationTest.java
index 2b66e0e1..7ae1db23 100644
--- a/src/test/java/org/openmaptiles/layers/TransportationTest.java
+++ b/src/test/java/org/openmaptiles/layers/TransportationTest.java
@@ -12,6 +12,7 @@
 import com.onthegomap.planetiler.reader.SimpleFeature;
 import com.onthegomap.planetiler.reader.SourceFeature;
 import com.onthegomap.planetiler.reader.osm.OsmElement;
+import com.onthegomap.planetiler.reader.osm.OsmRelationInfo;
 import com.onthegomap.planetiler.stats.Stats;
 import java.util.ArrayList;
 import java.util.List;
@@ -405,6 +406,46 @@ void testRouteWithoutNetworkType() {
     )), rendered);
   }
 
+  @Test
+  void testSegmentWithManyRoutes() {
+    List<OsmRelationInfo> relations = new ArrayList<>();
+    for (int route = 1; route <= 16; route++) {
+      int num = (route + 1) / 2; // to make dups
+      var rel = new OsmElement.Relation(route);
+      rel.setTag("type", "route");
+      rel.setTag("route", "road");
+      rel.setTag("network", "US:I");
+      rel.setTag("ref", Integer.toString(num));
+      rel.setTag("name", "Route " + num);
+      relations.addAll(profile.preprocessOsmRelation(rel));
+    }
+
+    FeatureCollector rendered = process(lineFeatureWithRelation(
+      relations,
+      Map.of(
+        "highway", "motorway",
+        "name", "New Jersey Turnpike",
+        "ref", "I 95;NJTP"
+      )));
+
+    assertFeatures(13, List.of(mapOf(
+      "_layer", "transportation",
+      "class", "motorway",
+      "_minzoom", 4
+    ), mapOf(
+      "_layer", "transportation_name",
+      "route_1", "US:I=1",
+      "route_2", "US:I=2",
+      "route_3", "US:I=3",
+      "route_4", "US:I=4",
+      "route_5", "US:I=5",
+      "route_6", "US:I=6",
+      "route_7", "US:I=7",
+      "route_8", "US:I=8",
+      "route_9", "<null>"
+    )), rendered);
+  }
+
   @Test
   void testMinorRouteRef() {
     var rel1 = new OsmElement.Relation(1);