Localization errors of low-cost GPS devices in railway worksite-like scenarios

Many well-known and efficient technologies for satellite-based localization in open space there exist; however, their accuracy and availability depend on several factors, such as the characteristics of the devices used, the surrounding environment, and the distance from reference stations. In the ALARP (A railway automatic track warning system based on distributed personal mobile terminals) system, it is required to accurately localize workers in railway worksites using low-cost GPS devices. In this paper we present an experimental campaign aimed to quantify the systematic and random contribution to localization errors of cheap GPS devices in railway worksite-like scenarios. The evaluation is performed comparing data from low-cost GPS devices to data collected using a highly accurate reference system. Results provide information to understand the feasibility of GPS-based solutions for the ALARP requirements on localization, and constitute a basis for the definition of a further, more extensive testing campaign.