diff --git a/css/30_highways.css b/css/30_highways.css
index 2122135889..05f18df067 100644
--- a/css/30_highways.css
+++ b/css/30_highways.css
@@ -1,13 +1,15 @@
-preset-icon-container/* highways */
+/* preset-icon-container highways */
 
 /* defaults */
 .preset-icon .icon.tag-highway.other-line {
     color: #fff;
     fill: #777;
 }
+
 path.line.casing.tag-highway {
     stroke: #444;
 }
+
 path.line.stroke.tag-highway {
     stroke: #ccc;
 }
diff --git a/modules/ui/fields/textarea.js b/modules/ui/fields/textarea.js
index 223121daeb..019480363f 100644
--- a/modules/ui/fields/textarea.js
+++ b/modules/ui/fields/textarea.js
@@ -8,18 +8,18 @@ import {
     utilRebind
 } from '../../util';
 import { uiLengthIndicator } from '..';
-
+import { svgIcon } from '../../svg/icon';   // ← ADDED
 
 export function uiFieldTextarea(field, context) {
     var dispatch = d3_dispatch('change');
     var input = d3_select(null);
+    var wrap = d3_select(null);              // ← ADDED
     var _lengthIndicator = uiLengthIndicator(context.maxCharsForTagValue())
         .silent(field.usage === 'changeset' && field.key === 'comment');
     var _tags;
 
-
     function textarea(selection) {
-        var wrap = selection.selectAll('.form-field-input-wrap')
+        wrap = selection.selectAll('.form-field-input-wrap')
             .data([0]);
 
         wrap = wrap.enter()
@@ -36,15 +36,24 @@ export function uiFieldTextarea(field, context) {
             .attr('dir', 'auto')
             .attr('id', field.domId)
             .call(utilNoAuto)
-            .on('input', change(true))
-            .on('blur', change())
-            .on('change', change())
+            .on('input', function () {
+                change(true)();
+                updatePatternValidation();    // ← ADDED
+            })
+            .on('blur', function () {
+                change()();
+                updatePatternValidation();    // ← ADDED
+            })
+            .on('change', function () {
+                change()();
+                updatePatternValidation();    // ← ADDED
+            })
             .merge(input);
 
         wrap.call(_lengthIndicator);
 
         function change(onInput) {
-            return function() {
+            return function () {
 
                 var val = utilGetSetValue(input);
                 if (!onInput) val = context.cleanTagValue(val);
@@ -58,9 +67,47 @@ export function uiFieldTextarea(field, context) {
             };
         }
     }
+    
+    function updatePatternValidation() {
+        if (!field.pattern || !wrap || wrap.empty()) return;
+
+        const value = utilGetSetValue(input).trim();
+
+        if (!value) {
+            wrap.selectAll('.form-field-pattern-info').remove();
+            return;
+        }
+
+        let isInvalid = false;
+        try {
+            const regex = new RegExp(field.pattern);
+            isInvalid = !regex.test(value);
+        } catch {
+            return;
+        }
 
+        const info = wrap.selectAll('.form-field-pattern-info')
+            .data(isInvalid ? [0] : []);
 
-    textarea.tags = function(tags) {
+        const enter = info.enter()
+            .append('div')
+            .attr('class', 'form-field-pattern-info');
+
+        enter
+            .append('span')
+            .call(svgIcon('#iD-icon-info'));
+
+        enter
+            .append('span')
+            .attr('class', 'form-field-pattern-info-text')
+            .text(t('inspector.invalid_format'));
+
+        info.exit().remove();
+    }
+    // ============================
+
+
+    textarea.tags = function (tags) {
         _tags = tags;
 
         var isMixed = Array.isArray(tags[field.key]);
@@ -73,10 +120,12 @@ export function uiFieldTextarea(field, context) {
         if (!isMixed) {
             _lengthIndicator.update(tags[field.key]);
         }
+
+        updatePatternValidation();   
     };
 
 
-    textarea.focus = function() {
+    textarea.focus = function () {
         input.node().focus();
     };
 
diff --git a/modules/validations/crossing_ways.js b/modules/validations/crossing_ways.js
index 3f2e27123f..5ca3aa149c 100644
--- a/modules/validations/crossing_ways.js
+++ b/modules/validations/crossing_ways.js
@@ -841,4 +841,4 @@ export function validationCrossingWays(context) {
     validation.type = type;
 
     return validation;
-}
+}
\ No newline at end of file