KIT | KIT-Bibliothek | Impressum

Towards Mobile Time-Dependent Route Planning

Kaufmann, Harris

Abstract: Road networks with time-dependent edge weights can describe rush hours and similar regular changes in traffic over a day. Optimal routes can be calculated efficiently using time-dependent Contraction Hierarchies. On mobile devices it is usually not possible and also not reasonable to hold the entire data in the limited main memory. Therefore the main performance bottleneck is the data access on the flash memory, which can only be read blockwise. For fast route query calculations, the number of accessed blocks has to be low. To achieve this, we first reduce the amount of data using a lossy compression. This introduces inaccuracies in the calculations hence not always the optimal route is chosen. Nevertheless using this method the result is still nearly exact because the average introduced delay compared to the optimal route is less than 0.001%. In the worst case a delay of about 0.1% occurs which still is too small to be noticed. Second, the data is rearranged in a way that increases the locality. This leads to a lower number of required block loads. For a road network of Germany we can answer random route queries with an average of 102 block loads. Assuming that a block access takes 1.3 ms, this can be done in 133 ms. Users perceive this as a nearly instant reaction. Everyday route calculations tend to be even smaller and can be calculated faster.


Zugehörige Institution(en) am KIT Institut für Theoretische Informatik (ITI)
Publikationstyp Hochschulschrift
Jahr 2013
Sprache Englisch
Identifikator DOI(KIT): 10.5445/IR/1000058829
URN: urn:nbn:de:swb:90-588296
KITopen ID: 1000058829
Verlag Karlsruhe
Umfang 49 S.
Abschlussart Abschlussarbeit - Bachelor
KIT – Die Forschungsuniversität in der Helmholtz-Gemeinschaft KITopen Landing Page