Engineering Oracles for Time-Dependent Road Networks

TL;DR

This paper presents new landmark-based oracles for efficient shortest path queries in large-scale time-dependent road networks, utilizing parallelism, compression, and novel approximation techniques to significantly improve query performance.

Contribution

It introduces a novel travel-time approximation method and a landmark hierarchy oracle, achieving substantial improvements over previous approaches in preprocessing and query efficiency.

Findings

30% faster query times than FLAT oracle

Doubled Dijkstra-rank speedup

HORN oracle outperforms FLAT in experiments

Abstract

We implement and experimentally evaluate landmark-based oracles for min-cost paths in large-scale time-dependent road networks. We exploit parallelism and lossless compression, combined with a novel travel-time approximation technique, to severely reduce preprocessing space and time. We significantly improve the FLAT oracle, improving the previous query time by $30\%$ and doubling the Dijkstra-rank speedup. We also implement and experimentally evaluate a novel oracle (HORN), based on a landmark hierarchy, achieving even better performance wrt to FLAT.