The new technology which will help expand Metro - and keep trains moving when power lines go down

Each of the 42 new Metro trains being built by Swiss firm Stadler will be equipped with battery technology that will allow them to run even if there is no power in the system’s overhead power lines.

Metro’s current fleet is entirely dependent on the electricity conducted by the overhead lines and a fault can cause an immediate and often lengthy shutdown of services, regularly frustrating passengers.

But the new carriages, due to start arriving from 2022, will be capable of running off an on-board battery for up to 45 minutes.

That means trains can keep moving in the event of an overhead line failure and passengers will never be left stranded in between stations or be forced to evacuate onto the tracks.

While that news will come as a major relief to regular commuters, battery power presents an even more tantalising prospect for communities that have been desperate for an expansion of the Metro.

That is because the ability to run trains without overhead lines makes it dramatically cheaper and easier to open new routes, potentially to places like Washington and Newcastle’s West End.

Each train battery will be capable of being upgraded so that it can run for 16km without overhead lines, potentially even more as technology improves.

Metro development director Neil Blagburn, who is heading up the delivery of the new fleet, believes such capabilities will make the Government far more likely to support and fund long-awaited extensions of the Metro.

He said the 16km off-wire running would allow for a new loop extending out from South Hylton, through Washington, connecting back to Pelaw.

He added that it would be “easy” to create new connections between existing Metro lines – potentially allowing a link-up from South Shields towards Sunderland.

Battery power would also solve the problem of running Metro trains on Network Rail lines, which operate at different voltages.

Mr Blagburn said: “You could remove the electrification from the complex parts of the route, say over historic structures or through tunnels.

“Electrify just perhaps the stations so you could have a charging point there and then at the end of the route before you turn back it will be sat there charging for seven minutes before you turn back again.

“That dramatically improves the business case. The more you can reduce the costs, the more it improves your cost-benefit ratio.”

He said that having a 45-minute window to allow engineers to restore power to overhead lines without there being any disruption to train services is a “big deal”, and will also avert a “nightmare scenario” in which power is lost at the main train depot in the morning and no trains can leave.

The batteries will emerge from the depot fully charged in the morning but will be continuously topped up throughout the day with power transferred from the overhead lines.