// Build the route URL
                        urlRoute0 = './application/helpers/prefetch.route.php?r=btr1002025_track.geojson&light='+slowMobileConnection+'&fingerprint=G4RyPvaGDBLIUPuGHaentZNUBFWlmCPl_mod_1746706289';

                        // Add GeoJSON Source if not yet added.
                        if (!map.getSource('route0')) {
                            map.addSource('route0', {
                                type: 'geojson',
                                data: urlRoute0                            });
                        }

                        // Add Route Layer if not yet added.
                        if (!map.getLayer('route0')) {
                            map.addLayer({
                                "id": "route0",
                                "type": "line",
                                "source": "route0",
                                "layout": {
                                    "line-join": "round",
                                    "line-cap": "round"
                                },
                                "paint": {
                                    "line-color": "#551a8b",
                                    "line-width": 3                                }
                            });
                        }

                                                    // Add Direction Arrow Layer if not yet added.
                            if (!map.getLayer('arrow-layer0')) {
                                map.addLayer({
                                  'id': 'arrow-layer0',
                                  'type': 'symbol',
                                  'source': 'route0',
                                  'layout': {
                                    'symbol-placement': 'line',
                                    'symbol-spacing': 200,
                                    'icon-allow-overlap': true,
                                    'icon-image': 'route-direction-arrow',
                                    'icon-size': 0.3,
                                    'visibility': 'visible'
                                  },
                                  'paint': {
                                    'icon-color': '#551a8b'
                                  }
                                });
                            }