Contraction of Timetable Networks with Realistic Transfers

TL;DR

This paper presents a method for contracting timetable networks with realistic transfer times, significantly reducing query times while maintaining accurate shortest path computations using an improved contraction algorithm and station graph model.

Contribution

It introduces an enhanced contraction algorithm and a station graph model that efficiently handle realistic transfer times in timetable networks.

Findings

Query times reduced to 1 ms

Preprocessing takes around 6 minutes

Effective handling of realistic transfer times

Abstract

We successfully contract timetable networks with realistic transfer times. Contraction gradually removes nodes from the graph and adds shortcuts to preserve shortest paths. This reduces query times to 1 ms with preprocessing times around 6 minutes on all tested instances. We achieve this by an improved contraction algorithm and by using a station graph model. Every node in our graph has a one-to-one correspondence to a station and every edge has an assigned collection of connections. Our graph model does not need parallel edges. The query algorithm does not compute a single earliest arrival time at a station but a set of arriving connections that allow best transfer opportunities.