diff --git a/config.js b/config.js
index 7182a85..9a2c856 100644
--- a/config.js
+++ b/config.js
@@ -78,6 +78,9 @@
         //'Mapsforge Tile Server': 'http://localhost:6090/{z}/{x}/{y}.png'
     };
 
+    // Initial route line transparency (0-1, overridden by stored slider setting)
+    BR.conf.defaultOpacity = 0.67;
+
     // Minimum transparency slider value on load, values between 0 and 1 (0=invisible).
     // 0 = no minimum, use stored setting; 1 = always reset to full visibility on load
     BR.conf.minOpacity = 0.3;
diff --git a/js/control/OpacitySlider.js b/js/control/OpacitySlider.js
index 3123789..847c961 100644
--- a/js/control/OpacitySlider.js
+++ b/js/control/OpacitySlider.js
@@ -8,7 +8,7 @@ BR.OpacitySlider = L.Control.extend({
         var container = L.DomUtil.create('div', 'leaflet-bar control-slider'),
             input = $('<input id="slider" type="text"/>'),
             item = localStorage.opacitySliderValue,
-            value = item ? parseInt(item) : 100,
+            value = item ? parseInt(item) : BR.conf.defaultOpacity * 100,
             minOpacity = (BR.conf.minOpacity || 0) * 100;
 
         if (value < minOpacity) {
diff --git a/js/index.js b/js/index.js
index 672652b..4838e0a 100644
--- a/js/index.js
+++ b/js/index.js
@@ -251,13 +251,13 @@
                 },
                 track: {
                     color: 'magenta',
-                    opacity: 1
+                    opacity: BR.conf.defaultOpacity
                 },
                 trackCasing: {
                     weight: 8,
                     color: 'white',
                     // assumed to be same as track, see setOpacity
-                    opacity: 1
+                    opacity: BR.conf.defaultOpacity
                 },
                 nodata: {
                     color: 'darkred'