Collision Course at Sea
Discussion on collision probabilities at sea
Blast Off!
If this article is titled Collision Course at Sea, why the nebula? I'll get to that, but first, as a scene-setter, do the following song lyrics ring a bell? "sitting in a tin can, Far above the world, Planet Earth is blue, And there's nothing I can do."
If you guessed David Bowie – Space Oddity , you got it!
Now to the nebula. Imagine you're sitting in a spaceship (or tin can), on a heading towards the center portion of the Milky Way Galaxy, circuits are dead, and there is nothing you can do (i.e., you're going in a straight line) unable to pilot your vessel. Outside of food and water supply, another concern is my chances of running into something. According to a December 2014 article from the Atlantic, my chances are 100% zero. Not only are my chances zero, but to collide with anything larger than space dust, I would need to travel across the entire Milky Way Galaxy 15000 times!
Collision Probability
Finite, or infinite, the universe is unfathomably large and filled with a lot of emptiness. While reading the referenced article, as a sailor, I wondered if a similar probability would apply to the vast ocean here on earth. After some research, I learned sadly; the answer was nothing near zero but more like 24%. By applying an Accident Risk Collision Probability Formula, and maritime accident statistics, the Centre for Marine Technology and Engineering estimates nearly one-quarter of accidents at sea are from a collision with another vessel or a static obstruction. So despite 139,397,000 square miles of ocean, if not vigilant, I have what I would consider a concerning chance of running into something.
Chances of an unnavigated vessel at sea colliding in the harbor or coastal approach areas take up a bulk of that 25%. However, if you take a close look at both The Office of Coast's Survey's Wrecks and Obstructions data in the map below, coupled with the spiderweb of U.S. Vessel Traffic (AIS Cargo Shipping Tracks 2020) graphic to the right, it seems a bit more plausible.
Obstructions
Explore and observe The Office of Coast's Survey's Wrecks and Obstructions using the interactive map to the right. In doing this, you will find that the densely populated dataset provides a good depiction of how the probability of collision at sea is very plausible if unnavigated.
Next
I'm peculiar, so the GIS junkie in me won't let me stop here. As a follow-up to this discussion, I'll take a deeper, more quantitative approach to answer the question using GIS. What processes are available to help codify the 25%? Perhaps Geostatistical analysis, a Histogram indicates the spatial distribution of the obstruction data is not symmetrical. Network Analysis, how would you build a cost network schema for the ocean? Will using existing AIS accident data do the trick? Feel free to provide feedback, and thank you for reading!
