When is a bus full?: A study of perception

Crowding on buses, trams and trains leads to a deteriorated performance of the public transport system through increased waiting times and vehicle bunching, and is naturally resented by its customers. In the past, i.e. in the absence of smart card ticketing system, crowding was difficult to measure in any detail and therefore to trace its impact on user behaviour, e.g. trip making, route and departure time choice by user characteristics. As a result stated preference surveys were the preferred instrument to measure its differential impact. Surprisingly, little research has been undertaken on the perception of the terms: full, crowed, overcrowded etc., used in such surveys. In this paper we describe an exercise, which made the perception the focus of its work. Using a set of images and a sample of users on crowded bus lines in Zürich we establish the likelihood that they will declare a bus full and link this to their socio-demographics