AIS fixes in the Puget Sound box on 1 June 2023: 277,574 from 703 vessels (read in 0.1 s) MMSI BaseDateTime LAT LON SOG COG VesselName VesselType 368252640 2023-06-01 00:00:02 47.72345 -122.64139 0.0 0.0 RUNRIG 37.0 368028070 2023-06-01 00:00:05 47.64409 -122.34321 0.0 291.6 GRUMPYCAT 36.0 367307370 2023-06-01 00:00:03 47.65774 -122.37130 0.0 1.4 NORTH AMERICAN 30.0 duplicate timestamps dropped: 10 time between fixes: median 179 s, 90th pct 240 s, max 21.3 h TrajectoryCollection: 364 trajectories longer than 1 km, built in 1.0 s (339 vessels moved less than 1 km and were left out) ObservationGapSplitter(gap=15 min): 403 trajectories after splitting at gaps in reception WSF WALLA WALLA: 1 trajectory, 1,270 fixes, 282.1 km, 00:00 to 23:59 UTC WSF WALLA WALLA speed from positions vs reported SOG (moving fixes, n=541): median |difference| 0.50 km/h, r = 0.926 direction from positions vs reported COG: median |difference| 1.2 degrees max computed speed 58.8 km/h (31.8 kn); max reported SOG 18.1 kn fixes implying more than 100 km/h across all vessels: 3 in 3 trajectories OutlierCleaner(v_max=100 km/h) removed 3 fixes OutlierCleaner(v_max=45 km/h) on WSF WALLA WALLA: removed 4 fixes; max speed now 41.0 km/h Washington State Ferries in the box: 7 trajectories from Cathlamet, Chimacum, Kittitas, Samish, Sealth, Tacoma, Walla Walla TrajectoryStopDetector(max_diameter=150 m, min_duration=5 min): 149 stops in 1.1 s stop places (stops within 500 m grouped): name n_stops median_dwell_min hours_stopped lon lat Vashon 38 13.4 41.4 -122.4635 47.5111 Seattle (Colman Dock) 31 20.5 11.3 -122.3402 47.6022 Fauntleroy 26 17.4 7.7 -122.3969 47.5232 Bainbridge Island 24 20.0 16.1 -122.5092 47.6221 Southworth 21 13.4 6.1 -122.4957 47.5132 Bremerton 8 16.6 6.8 -122.6247 47.5615 unnamed 1 1437.0 24.0 -122.3587 47.5873 StopSplitter(max_diameter=150 m, min_duration=5 min, min_length=1 km): 7 ferry trajectories -> 148 trips trips median_min median_km route Bainbridge Island - Seattle (Colman Dock) 44 30.3 13.7 Fauntleroy - Vashon 41 12.7 5.2 Southworth - Vashon 31 8.4 2.8 Bremerton - Seattle (Colman Dock) 15 54.0 25.5 Fauntleroy - Southworth 11 17.7 7.6 Seattle (Colman Dock) - edge of box 3 12.1 5.6 Bainbridge Island - edge of box 2 16.8 7.3 Bremerton - edge of box 1 41.9 19.2 WSF WALLA WALLA trips: 21, median crossing 29 min over 13.7 km generalising WSF WALLA WALLA (1,266 fixes): method tolerance unit points kept_pct spatial_max_m spatial_mean_m sync_mean_m sync_max_m secs Douglas-Peucker 2.0 m 1021 80.65 2.14 0.08 3.06 277.19 0.19 Douglas-Peucker 5.0 m 697 55.06 4.84 0.29 12.48 360.18 0.18 Douglas-Peucker 10.0 m 426 33.65 9.46 0.65 36.16 543.08 0.14 Douglas-Peucker 20.0 m 311 24.57 19.99 1.68 75.50 641.99 0.07 Douglas-Peucker 50.0 m 230 18.17 44.09 3.91 183.95 775.20 0.07 Douglas-Peucker 100.0 m 170 13.43 94.32 6.25 293.89 2399.97 0.07 Douglas-Peucker 200.0 m 139 10.98 135.23 7.95 429.71 5228.33 0.06 Douglas-Peucker 400.0 m 100 7.90 193.92 12.28 692.65 5228.33 0.04 Top-down time ratio 2.0 m 1054 83.25 1.75 0.02 0.17 2.00 1.43 Top-down time ratio 5.0 m 801 63.27 4.58 0.14 0.92 4.99 1.11 Top-down time ratio 10.0 m 571 45.10 9.22 0.38 2.39 9.85 0.92 Top-down time ratio 20.0 m 413 32.62 17.52 1.16 4.51 19.81 0.75 Top-down time ratio 50.0 m 314 24.80 40.11 2.96 7.17 49.84 0.63 Top-down time ratio 100.0 m 233 18.40 95.27 4.34 16.43 98.35 0.74 Top-down time ratio 200.0 m 168 13.27 132.26 6.27 39.99 198.76 0.52 Top-down time ratio 400.0 m 110 8.69 179.65 8.49 88.99 391.10 0.44 Min. time delta 2.0 min 631 49.84 127.20 1.80 11.85 289.95 0.04 Min. time delta 3.0 min 422 33.33 159.29 3.71 28.29 537.35 0.04 Min. time delta 5.0 min 256 20.22 161.86 6.50 69.93 648.04 0.04 Min. time delta 10.0 min 137 10.82 333.46 12.65 202.45 1357.77 0.04 Min. time delta 15.0 min 94 7.42 283.56 14.25 358.39 1801.59 0.04 Min. time delta 20.0 min 71 5.61 351.44 16.87 595.96 2663.53 0.04 Min. time delta 30.0 min 48 3.79 714.96 42.11 1080.73 3881.30 0.04 Min. time delta 60.0 min 25 1.97 1706.54 208.92 2797.67 9215.83 0.04 figure 5 zooms on the Bainbridge approach of one crossing: 15:48-16:17 UTC, 28 original fixes flow map from 253 vessels that moved faster than 3 kn: 7,211 significant points, 94 clusters, 319 flows in 9.2 s flow weights: median 5, max 108; flows with weight >= 5: 174 wrote ferry_trip.gpx: 28 track points, 3.5 KB read back with geopandas (layer='track_points'): 28 rows, columns include ['track_fid', 'track_seg_point_id', 'time', 'geometry'] GPX trajectory: 13.64 km in 0:29:24, max speed 33.0 km/h (original trip 13.64 km) gpxpy: Wsf Walla Walla 2023-06-01 15:48 UTC; first point 47.62192, -122.50777 at 2023-06-01 15:48:12; gpxpy length_2d 13.63 km