diff --git a/api/obs/api/routes/tracks.py b/api/obs/api/routes/tracks.py
index 076d45e..1353d03 100644
--- a/api/obs/api/routes/tracks.py
+++ b/api/obs/api/routes/tracks.py
@@ -1,7 +1,5 @@
 import logging
-import queue
 import re
-import tarfile
 from json import load as jsonload
 from os.path import join, exists, isfile
 
@@ -12,6 +10,7 @@ from sqlalchemy.orm import joinedload
 
 from obs.api.app import api, require_auth, read_api_key, json
 from obs.api.db import Track, Comment, DuplicateTrackFileError
+from obs.api.utils import tar_of_tracks
 
 log = logging.getLogger(__name__)
 
@@ -59,39 +58,6 @@ async def _return_tracks(req, extend_query, limit, offset, order_by=None):
         },
     )
 
-class StreamerHelper:
-    def __init__(self, response):
-        self.response = response
-        self.towrite = queue.Queue()
-
-    def write(self, data):
-        self.towrite.put(data)
-
-    async def send_all(self):
-        while True:
-            try:
-                tosend = self.towrite.get(block=False)
-                await self.response.send(tosend)
-            except queue.Empty:
-                break
-
-
-async def tar_of_tracks(req, files):
-
-    response = await req.respond(content_type="application/x-gtar", headers={'Content-Disposition': 'attachment; filename="tracks.tar.bz2"'})
-
-    helper = StreamerHelper(response)
-
-    tar = tarfile.open(name=None, fileobj=helper, mode="w|bz2", bufsize=256 * 512)
-    for fname in files:
-        logging.info(f"sending {fname}")
-        with open(fname, "rb") as fobj:
-            tar.addfile(tar.gettarinfo(fname),fobj)
-            await helper.send_all()
-    tar.close()
-    await helper.send_all()
-
-    await response.eof()
 
 @api.get("/tracks")
 async def get_tracks(req):
diff --git a/api/obs/api/utils.py b/api/obs/api/utils.py
index d4a8a88..289eb8c 100644
--- a/api/obs/api/utils.py
+++ b/api/obs/api/utils.py
@@ -1,7 +1,11 @@
+import queue
+import tarfile
 from datetime import datetime
 import dateutil.parser
 from sanic.exceptions import InvalidUsage
 
+from obs.api.routes.tracks import log
+
 RAISE = object()
 
 
@@ -76,3 +80,38 @@ class chunk:
                 if len(current):
                     yield current
                 break
+
+
+async def tar_of_tracks(req, files):
+
+    response = await req.respond(content_type="application/x-gtar", headers={'Content-Disposition': 'attachment; filename="tracks.tar.bz2"'})
+
+    helper = StreamerHelper(response)
+
+    tar = tarfile.open(name=None, fileobj=helper, mode="w|bz2", bufsize=256 * 512)
+    for fname in files:
+        log.info("Write file to tar: %s", fname)
+        with open(fname, "rb") as fobj:
+            tar.addfile(tar.gettarinfo(fname),fobj)
+            await helper.send_all()
+    tar.close()
+    await helper.send_all()
+
+    await response.eof()
+
+
+class StreamerHelper:
+    def __init__(self, response):
+        self.response = response
+        self.towrite = queue.Queue()
+
+    def write(self, data):
+        self.towrite.put(data)
+
+    async def send_all(self):
+        while True:
+            try:
+                tosend = self.towrite.get(block=False)
+                await self.response.send(tosend)
+            except queue.Empty:
+                break
diff --git a/frontend/src/pages/MapPage/index.tsx b/frontend/src/pages/MapPage/index.tsx
index a5a5ac7..e215077 100644
--- a/frontend/src/pages/MapPage/index.tsx
+++ b/frontend/src/pages/MapPage/index.tsx
@@ -80,6 +80,7 @@ const getEventsLayer = () => ({
   "source-layer": "obs_events",
   paint: {
     "circle-radius": ["interpolate", ["linear"], ["zoom"], 14, 3, 17, 8],
+    "circle-opacity": ["interpolate",["linear"],["zoom"],8,0.1,9,0.3,10,0.5,11,1],
     "circle-color": colorByDistance("distance_overtaker"),
   },
   minzoom: 8,
diff --git a/frontend/src/pages/MyTracksPage.tsx b/frontend/src/pages/MyTracksPage.tsx
index b336282..cf31702 100644
--- a/frontend/src/pages/MyTracksPage.tsx
+++ b/frontend/src/pages/MyTracksPage.tsx
@@ -235,7 +235,7 @@ function TracksTable({ title }) {
   };
 
   const bulkAction = async (action: string) => {
-    const data = await api.post("/tracks/bulk", {
+    const response = await api.post("/tracks/bulk", {
       body: {
         action,
         tracks: Object.keys(selectedTracks),
@@ -243,7 +243,7 @@ function TracksTable({ title }) {
       returnResponse: true
     });
     if (action === "download") {
-       download(await data.blob(), "tracks.tar.bz2", "application/x-gtar");
+       download(await response.blob(), "tracks.tar.bz2", "application/x-gtar");
     }
 
     setShowBulkDelete(false);