We now have Pictures of the World TSP Tour.

To provide a large-scale traveling salesman problem challenge, we put together data from the National Imagery and Mapping Agency database of geographic feature names and data from the Geographic Names Information System (GNIS), to create a 1,904,711-city instance of locations throughout the world. From the data bases, we selected all locations that were registered as populated cities or towns, and also included several research bases in Antarctica.

Each of the cities is specfied by its latitude and longitude, given in decimal form (rather than minutes and seconds). The cost of travel between cities is specified by an approximation to the great circle distance on the Earth (treating the Earth as a ball). This cost function is a variation of the TSPLIB GEO-norm, adjusted to handle decimal degrees and scaled to provide the distance in meters rather than in kilometers. We call this cost function the GEOM-norm; a frament of C-code to compute the travel costs can be found here.

The best reported tour for the World TSP was found by by Keld Helsgaun using a variant of his LKH heuristic algorithm. The tour of length 7,515,877,991 was found on May 12, 2009, improving Helsgaun's previous record of 7,515,947,511 found on November 27, 2008. Previous best known tours were of length 7,517,285,610 also by Helsgaun (September 16, 2003) and of length 7,518,425,642 by Hung Dinh Nguyen, Ikuo Yoshihara, Kunihito Yamamori, and Moritoshi Yasunaga (June 2, 2003), using a combination of iterated Lin-Kernighan and a parallel hybrid genetic algorithm.

The current best lower bound on the length of a tour for the World TSP is 7,512,218,268. This bound was established by the Concorde TSP code (June 5, 2007), using CPLEX as a linear-prgramming solver. The bound shows that Keld Helsgaun's tour has length at most 0.0487% greater than the length of an optimal tour.

We will be most happy to report any improved tour or improved lower bound that you may find.

Data  (Gzipped TSPLIB Format, world.tsp.gz, 11.5 mbytes)

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Last Updated:  May 12, 2009
Contact:  bico@isye.gatech.edu