//There is no reason the rest of the UK rail network has to change (if indeed that is what is happening now) to a European or inferior system. If an upgrade is to happen, then the best affordable system should be used, regardless of whether we are in the EU or not. //
Gromit, the railway Technical Specifications for Interoperability (TSIs) are what govern rail standards in the UK, tempered by UK National Notified Technical Rules, where interoperability is not practical (for instance, the UK's loading gauge is smaller than the UIC gauge used in Europe). The TSIs mandate a signal control system known as European Rail Traffic Management System (ERTMS) on all rail routes except those where interoperable traffic wouldn't reasonably be expected to go. The trial system is in use in Wales, and the first mainline installations will be commissioned with the introduction of new trains on GWR and ECML. It is hideously expensive, in particular with regard to retro fitting trains that weren't designed for ERTMS but still have 20 years plus of serviceable life left. it will be particularly painful for freight operators who are already operating at the fiscal limit, with only a nod to the government for the operation of 60T trucks in the UK required to make railfreight uneconomic.