diff --git a/main/src/main/java/org/mobilitydata/gtfsvalidator/validator/PathwayModeFieldsValidator.java b/main/src/main/java/org/mobilitydata/gtfsvalidator/validator/PathwayModeFieldsValidator.java
new file mode 100644
index 0000000000..ff4a062ab5
--- /dev/null
+++ b/main/src/main/java/org/mobilitydata/gtfsvalidator/validator/PathwayModeFieldsValidator.java
@@ -0,0 +1,130 @@
+package org.mobilitydata.gtfsvalidator.validator;
+
+import static org.mobilitydata.gtfsvalidator.notice.SeverityLevel.WARNING;
+
+import org.mobilitydata.gtfsvalidator.annotation.GtfsValidationNotice;
+import org.mobilitydata.gtfsvalidator.annotation.GtfsValidationNotice.FileRefs;
+import org.mobilitydata.gtfsvalidator.annotation.GtfsValidator;
+import org.mobilitydata.gtfsvalidator.notice.MissingRecommendedFieldNotice;
+import org.mobilitydata.gtfsvalidator.notice.NoticeContainer;
+import org.mobilitydata.gtfsvalidator.notice.ValidationNotice;
+import org.mobilitydata.gtfsvalidator.table.GtfsPathway;
+import org.mobilitydata.gtfsvalidator.table.GtfsPathwayMode;
+import org.mobilitydata.gtfsvalidator.table.GtfsPathwaySchema;
+
+/**
+ * Validates the pathway fields whose expectations depend on {@code pathway_mode}.
+ *
+ * <ul>
+ *   <li>{@code length} is recommended for walkways ({@code pathway_mode=1}), fare gates ({@code
+ *       pathway_mode=6}) and exit gates ({@code pathway_mode=7}).
+ *   <li>{@code stair_count} is recommended for stairs ({@code pathway_mode=2}).
+ *   <li>{@code traversal_time} is recommended for moving sidewalks ({@code pathway_mode=3}),
+ *       escalators ({@code pathway_mode=4}) and elevators ({@code pathway_mode=5}).
+ *   <li>{@code max_slope} should only be used with walkways ({@code pathway_mode=1}) and moving
+ *       sidewalks ({@code pathway_mode=3}).
+ * </ul>
+ *
+ * <p>Generated notices: {@link MissingRecommendedFieldNotice}, {@link
+ * IrrelevantMaxSlopeSetForPathwayModeNotice}.
+ */
+@GtfsValidator
+public class PathwayModeFieldsValidator extends SingleEntityValidator<GtfsPathway> {
+
+  @Override
+  public void validate(GtfsPathway entity, NoticeContainer noticeContainer) {
+    GtfsPathwayMode pathwayMode = entity.pathwayMode();
+
+    // A missing or unusable pathway_mode is already reported by the parser. Without a usable mode
+    // there is nothing to check these fields against, so reporting on them here would only add
+    // noise.
+    if (pathwayMode == GtfsPathwayMode.UNRECOGNIZED) {
+      return;
+    }
+
+    if (recommendsLength(pathwayMode) && !entity.hasLength()) {
+      noticeContainer.addValidationNotice(
+          new MissingRecommendedFieldNotice(
+              GtfsPathway.FILENAME, entity.csvRowNumber(), GtfsPathway.LENGTH_FIELD_NAME));
+    }
+
+    if (pathwayMode == GtfsPathwayMode.STAIRS && !entity.hasStairCount()) {
+      noticeContainer.addValidationNotice(
+          new MissingRecommendedFieldNotice(
+              GtfsPathway.FILENAME, entity.csvRowNumber(), GtfsPathway.STAIR_COUNT_FIELD_NAME));
+    }
+
+    if (recommendsTraversalTime(pathwayMode) && !entity.hasTraversalTime()) {
+      noticeContainer.addValidationNotice(
+          new MissingRecommendedFieldNotice(
+              GtfsPathway.FILENAME, entity.csvRowNumber(), GtfsPathway.TRAVERSAL_TIME_FIELD_NAME));
+    }
+
+    // The spec defines both an empty max_slope and a max_slope of 0 as "no slope", so a zero value
+    // carries no more meaning than leaving the field out and is not worth reporting.
+    if (!allowsMaxSlope(pathwayMode) && entity.hasMaxSlope() && entity.maxSlope() != 0) {
+      noticeContainer.addValidationNotice(new IrrelevantMaxSlopeSetForPathwayModeNotice(entity));
+    }
+  }
+
+  private static boolean recommendsLength(GtfsPathwayMode pathwayMode) {
+    switch (pathwayMode) {
+      case WALKWAY:
+      case FARE_GATE:
+      case EXIT_GATE:
+        return true;
+      default:
+        return false;
+    }
+  }
+
+  private static boolean recommendsTraversalTime(GtfsPathwayMode pathwayMode) {
+    switch (pathwayMode) {
+      case MOVING_SIDEWALK:
+      case ESCALATOR:
+      case ELEVATOR:
+        return true;
+      default:
+        return false;
+    }
+  }
+
+  private static boolean allowsMaxSlope(GtfsPathwayMode pathwayMode) {
+    switch (pathwayMode) {
+      case WALKWAY:
+      case MOVING_SIDEWALK:
+        return true;
+      default:
+        return false;
+    }
+  }
+
+  /**
+   * A pathway that is not a walkway or a moving sidewalk defines `max_slope`.
+   *
+   * <p>The GTFS specification states that `max_slope` should only be used with walkways
+   * (`pathway_mode=1`) and moving sidewalks (`pathway_mode=3`). A `max_slope` of `0` means no slope
+   * and is not reported.
+   */
+  @GtfsValidationNotice(severity = WARNING, files = @FileRefs({GtfsPathwaySchema.class}))
+  static class IrrelevantMaxSlopeSetForPathwayModeNotice extends ValidationNotice {
+    /** The row number of the faulty record. */
+    private final int csvRowNumber;
+
+    /** The `pathway_id` of the faulty record. */
+    private final String pathwayId;
+
+    /** The `pathway_mode` of the faulty record. */
+    private final int pathwayMode;
+
+    /** The `max_slope` defined on the faulty record. */
+    private final double maxSlope;
+
+    IrrelevantMaxSlopeSetForPathwayModeNotice(GtfsPathway pathway) {
+      this.csvRowNumber = pathway.csvRowNumber();
+      this.pathwayId = pathway.pathwayId();
+      this.pathwayMode = pathway.pathwayMode().getNumber();
+      this.maxSlope = pathway.maxSlope();
+    }
+  }
+}
diff --git a/main/src/test/java/org/mobilitydata/gtfsvalidator/validator/NoticeFieldsTest.java b/main/src/test/java/org/mobilitydata/gtfsvalidator/validator/NoticeFieldsTest.java
index 7a6840a1f0..5a8315b4af 100644
--- a/main/src/test/java/org/mobilitydata/gtfsvalidator/validator/NoticeFieldsTest.java
+++ b/main/src/test/java/org/mobilitydata/gtfsvalidator/validator/NoticeFieldsTest.java
@@ -144,6 +144,7 @@ public void testNoticeClassFieldNames() {
             "match2",
             "matchCount",
             "maxShapeDistanceTraveled",
+            "maxSlope",
             "maxTripDistanceTraveled",
             "message",
             "minServiceStartDate",
diff --git a/main/src/test/java/org/mobilitydata/gtfsvalidator/validator/PathwayModeFieldsValidatorTest.java b/main/src/test/java/org/mobilitydata/gtfsvalidator/validator/PathwayModeFieldsValidatorTest.java
new file mode 100644
index 0000000000..419fd148e5
--- /dev/null
+++ b/main/src/test/java/org/mobilitydata/gtfsvalidator/validator/PathwayModeFieldsValidatorTest.java
@@ -0,0 +1,197 @@
+package org.mobilitydata.gtfsvalidator.validator;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import java.util.List;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+import org.mobilitydata.gtfsvalidator.notice.MissingRecommendedFieldNotice;
+import org.mobilitydata.gtfsvalidator.notice.NoticeContainer;
+import org.mobilitydata.gtfsvalidator.notice.ValidationNotice;
+import org.mobilitydata.gtfsvalidator.table.GtfsPathway;
+import org.mobilitydata.gtfsvalidator.table.GtfsPathwayMode;
+
+@RunWith(JUnit4.class)
+public class PathwayModeFieldsValidatorTest {
+
+  // stair_count is recommended for stairs (pathway_mode=2).
+
+  @Test
+  public void stairsWithoutStairCount_yieldsNotice() {
+    assertThat(validationNoticesFor(pathway(GtfsPathwayMode.STAIRS).build()))
+        .containsExactly(new MissingRecommendedFieldNotice("pathways.txt", 2, "stair_count"));
+  }
+
+  @Test
+  public void stairsWithStairCount_yieldsNoNotice() {
+    assertThat(validationNoticesFor(pathway(GtfsPathwayMode.STAIRS).setStairCount(5).build()))
+        .isEmpty();
+  }
+
+  @Test
+  public void stairsWithNegativeStairCount_yieldsNoNotice() {
+    // The spec says a negative stair_count describes walking down, so it is still defined.
+    assertThat(validationNoticesFor(pathway(GtfsPathwayMode.STAIRS).setStairCount(-5).build()))
+        .isEmpty();
+  }
+
+  @Test
+  public void nonStairsWithoutStairCount_yieldsNoStairCountNotice() {
+    for (GtfsPathwayMode mode : GtfsPathwayMode.values()) {
+      if (mode == GtfsPathwayMode.STAIRS) {
+        continue;
+      }
+      assertThat(validationNoticesFor(pathway(mode).setTraversalTime(30).build()))
+          .doesNotContain(new MissingRecommendedFieldNotice("pathways.txt", 2, "stair_count"));
+    }
+  }
+
+  // traversal_time is recommended for moving sidewalks, escalators and elevators.
+
+  @Test
+  public void mechanicalPathwaysWithoutTraversalTime_yieldNotice() {
+    for (GtfsPathwayMode mode :
+        List.of(
+            GtfsPathwayMode.MOVING_SIDEWALK, GtfsPathwayMode.ESCALATOR, GtfsPathwayMode.ELEVATOR)) {
+      assertThat(validationNoticesFor(pathway(mode).build()))
+          .containsExactly(new MissingRecommendedFieldNotice("pathways.txt", 2, "traversal_time"));
+    }
+  }
+
+  @Test
+  public void mechanicalPathwaysWithTraversalTime_yieldNoNotice() {
+    for (GtfsPathwayMode mode :
+        List.of(
+            GtfsPathwayMode.MOVING_SIDEWALK, GtfsPathwayMode.ESCALATOR, GtfsPathwayMode.ELEVATOR)) {
+      assertThat(validationNoticesFor(pathway(mode).setTraversalTime(45).build())).isEmpty();
+    }
+  }
+
+  @Test
+  public void walkwayWithoutTraversalTime_yieldsNoNotice() {
+    assertThat(validationNoticesFor(pathway(GtfsPathwayMode.WALKWAY).setLength(12.0).build()))
+        .isEmpty();
+  }
+
+  // length is recommended for walkways, fare gates and exit gates.
+
+  @Test
+  public void pathwaysRecommendingLengthWithoutLength_yieldNotice() {
+    for (GtfsPathwayMode mode :
+        List.of(GtfsPathwayMode.WALKWAY, GtfsPathwayMode.FARE_GATE, GtfsPathwayMode.EXIT_GATE)) {
+      assertThat(validationNoticesFor(pathway(mode).build()))
+          .containsExactly(new MissingRecommendedFieldNotice("pathways.txt", 2, "length"));
+    }
+  }
+
+  @Test
+  public void pathwaysRecommendingLengthWithLength_yieldNoNotice() {
+    for (GtfsPathwayMode mode :
+        List.of(GtfsPathwayMode.WALKWAY, GtfsPathwayMode.FARE_GATE, GtfsPathwayMode.EXIT_GATE)) {
+      assertThat(validationNoticesFor(pathway(mode).setLength(12.0).build())).isEmpty();
+    }
+  }
+
+  @Test
+  public void zeroLength_yieldsNoNotice() {
+    // Unlike max_slope, the spec gives no special meaning to a length of 0, so it counts as
+    // defined.
+    assertThat(validationNoticesFor(pathway(GtfsPathwayMode.WALKWAY).setLength(0.0).build()))
+        .isEmpty();
+  }
+
+  @Test
+  public void stairsWithoutLength_yieldsNoLengthNotice() {
+    assertThat(validationNoticesFor(pathway(GtfsPathwayMode.STAIRS).setStairCount(5).build()))
+        .doesNotContain(new MissingRecommendedFieldNotice("pathways.txt", 2, "length"));
+  }
+
+  // max_slope should only be used with walkways and moving sidewalks.
+
+  @Test
+  public void maxSlopeOnDisallowedMode_yieldsNotice() {
+    GtfsPathway entity =
+        pathway(GtfsPathwayMode.ELEVATOR).setMaxSlope(0.083).setTraversalTime(30).build();
+    assertThat(validationNoticesFor(entity))
+        .containsExactly(
+            new PathwayModeFieldsValidator.IrrelevantMaxSlopeSetForPathwayModeNotice(entity));
+  }
+
+  @Test
+  public void maxSlopeOnWalkwayOrMovingSidewalk_yieldsNoNotice() {
+    assertThat(
+            validationNoticesFor(
+                pathway(GtfsPathwayMode.WALKWAY).setMaxSlope(0.083).setLength(12.0).build()))
+        .isEmpty();
+    assertThat(
+            validationNoticesFor(
+                pathway(GtfsPathwayMode.MOVING_SIDEWALK)
+                    .setMaxSlope(0.083)
+                    .setTraversalTime(30)
+                    .build()))
+        .isEmpty();
+  }
+
+  @Test
+  public void zeroMaxSlopeOnDisallowedMode_yieldsNoNotice() {
+    // The spec treats an empty max_slope and a max_slope of 0 alike, both meaning no slope.
+    GtfsPathway entity =
+        pathway(GtfsPathwayMode.ELEVATOR).setMaxSlope(0.0).setTraversalTime(30).build();
+    assertThat(validationNoticesFor(entity)).isEmpty();
+  }
+
+  @Test
+  public void negativeMaxSlopeOnDisallowedMode_yieldsNotice() {
+    // A negative slope describes a downward pathway, so it is a real value.
+    GtfsPathway entity =
+        pathway(GtfsPathwayMode.EXIT_GATE).setMaxSlope(-0.05).setLength(12.0).build();
+    assertThat(validationNoticesFor(entity))
+        .containsExactly(
+            new PathwayModeFieldsValidator.IrrelevantMaxSlopeSetForPathwayModeNotice(entity));
+  }
+
+  // An unusable pathway_mode is reported by the parser, so this validator stays quiet.
+
+  @Test
+  public void maxSlopeOnUnrecognizedMode_yieldsNoNotice() {
+    GtfsPathway entity =
+        new GtfsPathway.Builder()
+            .setCsvRowNumber(2)
+            .setPathwayId("pathway1")
+            .setFromStopId("stop1")
+            .setToStopId("stop2")
+            .setPathwayMode(9)
+            .setMaxSlope(0.083)
+            .build();
+    assertThat(validationNoticesFor(entity)).isEmpty();
+  }
+
+  @Test
+  public void maxSlopeWithoutPathwayMode_yieldsNoNotice() {
+    GtfsPathway entity =
+        new GtfsPathway.Builder()
+            .setCsvRowNumber(2)
+            .setPathwayId("pathway1")
+            .setFromStopId("stop1")
+            .setToStopId("stop2")
+            .setMaxSlope(0.083)
+            .build();
+    assertThat(validationNoticesFor(entity)).isEmpty();
+  }
+
+  private static GtfsPathway.Builder pathway(GtfsPathwayMode pathwayMode) {
+    return new GtfsPathway.Builder()
+        .setCsvRowNumber(2)
+        .setPathwayId("pathway1")
+        .setFromStopId("stop1")
+        .setToStopId("stop2")
+        .setPathwayMode(pathwayMode);
+  }
+
+  private static List<ValidationNotice> validationNoticesFor(GtfsPathway entity) {
+    NoticeContainer noticeContainer = new NoticeContainer();
+    new PathwayModeFieldsValidator().validate(entity, noticeContainer);
+    return noticeContainer.getValidationNotices();
+  }
+}