# Scientists have calculated the world's longest direct land route: 11,241 km

*Illustration by Patrick Anderson, on which in 2012 he suggested the longest possible direct route by sea.*

In December 2012, a curious discussion erupted in / r / MapPorn. One of the users under the nickname Kepleronlyknows (Patrick Anderson) published an image with a world map on which he depicted a direct shipping route. Patrick hypothesized that this is the longest direct route that can be laid on water on our planet. Without a single turn, you will sail in a straight line for about 32,000 kilometers, starting in the Pakistan region and finishing in Kamchatka. An absolutely direct route passes through Africa, South America and across the Pacific Ocean to Russia itself.

Of course, the author calculated by intuition. He invited the forum users to test his hypothesis and find a longer route, if one exists. Or try to prove that this route is the most direct.

The message caused a heated debate: hundreds of members of the forum bent over maps and globes. The main question is whether this record can be broken (

*UPD: about the same debate unfolded in the comments on this article on GT*). Along the way, another question arose: what is the longest route in the world in a straight line by land rather than by sea? That is, how much you can go in a straight line, never once stumbled upon the sea.

It is clear that the resulting curve should belong to a large circle around the sphere of the globe (for simplicity, we can consider it to be a sphere). This circle connects the points on the surface of the sphere along the shortest possible path. But how to find these circles with the right solution?

*The circle that connects the highest and lowest points on the Earth’s surface.*

Apparently, among the “hot heads” on the Reddit forum, there were still people with a fundamental education who thoroughly approached the solution to the problem. So, take a look at the scientific work of Rohan Chabukswar from the United Technologies Research Center (Ireland) and Kushal Mukherjee from the IBM Research Research Unit in India. These guys developed a reliable algorithm for calculating the longest straight path on land or at sea. The scientific article was published on April 9, 2018 on the preprint site arXiv.og ( arXiv: 1804.07389v1 ).

Of course, it immediately comes to mind to solve the brute force problem - to sort out all possible circles along the earth's sphere. But this is too demanding a task: on a world map with a resolution of 1.85 km, more than 230 billion of such circles will be obtained. Each of them consists of 21,600 individual points, which is a total of more than five trillion points for calculation.

But Chabuksvar and Mukherjee developed a faster method based on an algorithm known as the branch and bound method.

Branch and Border Method- a general algorithmic method for finding optimal solutions to various optimization problems, especially discrete and combinatorial optimization. In essence, the method is a variation of exhaustive search with elimination of subsets of feasible solutions that obviously do not contain optimal solutions. In fact, instead of evaluating all the solutions, the algorithm checks one branch after another (an analogue of brute force). But another method, called restriction, significantly reduces the scope of the search. Each branch contains a subset of potential solutions, one of which is the optimal solution. The trick is to find the property of the subsets, which depends on how close the solutions are to the optimal.

This type of computation required much less computational resources: “The algorithm returned the longest path in about 10 minutes of calculations for the waterway and 45 minutes of calculations for the earth's path on a standard laptop,” the researchers say.

And it turned out that Kepleronlyknows was absolutely right. The longest direct waterway begins in the city of Sonmiani, Balochistan Province, Pakistan, where the missile test site is located. The route runs between Africa and Madagascar, and then between Antarctica and Tierra del Fuego in South America - and ends in the Karagin region of the Kamchatka Territory in Russia. The length of the route is

**32089 kilometers 700 meters**.

The longest land journey begins near Jinjiang City County in Fujian Province, Quanzhou County (China). It goes through Mongolia Kazakhstan, Russia and finally reaches Europe to end near the city of Sagres in Portugal. In general, the route passes through 15 countries and amounts to 11,241 kilometers 100 meters - more than 101 degrees around the earth's circumference.

Which countries go through the world's longest direct land route:

- China (Jinjiang, 24 ° 32'55 '' N, 118 ° 38'3 '' E)
- Mongolia
- Kazakhstan
- Russia
- Belarus ( three times )
- Ukraine (two times)
- Poland
- Czech
- Germany
- Austria
- Liechtenstein
- Switzerland
- France
- Spain
- Portugal (Sagres, 37 ° 1'30 '' N, 8 ° 55'0 '' W)

If you are interested, you can accurately calculate through which cities the world’s record route passes. Suddenly some crazy traveler decides to go straight in a straight line through all of Asia and Europe. Although, probably, the question should be posed differently: who will be the first to do it and when?