Modeling “Wrong Side” Failures Caused by Geomagnetically Induced Currents in Electrified Railway Signaling Systems in the UK

Abstract

The majority of studies into space weather impacts on ground-based systems focus on power supply networks and gas and oil pipelines. The effects on railway infrastructure remain a sparsely covered aspect even though these system are known to have experienced adverse effects in the past as a result of geomagnetic activity. This study extends recent modeling of geomagnetic effects on DC signaling for AC-electrified railways in the UK that studied “right side” failures in which green signals are turned to red. The extended model reported here allows the study of “wrong side” failures where red signals are turned green: a failure mode that is potentially more dangerous. The results show that the geoelectric field threshold at which “wrong side” failures occur is lower than for “right side” failures. This misoperation field level occurs on a timescale of once every 10 or 20 years. We also show that the estimated electric field caused by a 1-in-100 year event would cause a significant number of “wrong side” failures at multiple points along the railway lines studied.