A Critical Analysis of the What3Words Geocoding Algorithm

TL;DR

This paper critically examines the What3Words geocoding system, revealing that its algorithm produces many similar addresses that could cause confusion, raising concerns about its reliability in emergency and critical applications.

Contribution

The paper provides an in-depth analysis of the What3Words algorithm, highlighting its propensity to generate confusable addresses and discussing the implications for safety-critical uses.

Findings

Many pairs of addresses are confusable due to the algorithm.

Some confusable addresses are geographically close.

The reliability of What3Words in emergencies is questionable.

Abstract

What3Words is a geocoding application that uses triples of words instead of alphanumeric coordinates to identify locations. What3Words has grown rapidly in popularity over the past few years and is used in logistical applications worldwide, including by emergency services. What3Words has also attracted criticism for being less reliable than claimed, in particular that the chance of confusing one address with another is high. This paper investigates these claims and shows that the What3Words algorithm for assigning addresses to grid boxes creates many pairs of confusable addresses, some of which are quite close together. The implications of this for the use of What3Words in critical or emergency situations is discussed.