The Strategic Rail Authority made an extensive study of the effects of ERTMS on the UK railway. Network Rail now leads the National ERTMS Programme and has updated the SRA’s work. If applied when a line is being resignalled, ERTMS can reduce the overall cost of the railway and support capacity enhancement. ERTMS also produces a small safety improvement over and above the high level of train protection afforded by TPWS. However, the capacity and cost benefits only apply if ERTMS Level 2 is used to eliminate lineside signalling. The Cambrian Early Deployment Scheme will demonstrate the use of this technology in the UK for the first time.