This will come as a godsend to regular passengers who have become frustrated by the increasingly unreliable system.
The first trains are expected to arrive in late 2021, and Metro bosses have now put together a list of specifications of what must be included, and other options still to be decided.
Managing director of Nexus, Tobyn Hughes, said: "The trains we will buy will transform the reliability of the system, as well as reducing energy usage and updating the experience of travelling by Metro. We will also future-proof them so that they have the capability of serving more destinations on a wider network in the future."
“We are in the process of finalising the specification, and we have used extensive market research to inform the interior layout, for example by providing more standing room and space for luggage.
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"We are really looking forward to seeing the designs that manufacturers come up with so that we can choose the best possible trains for our existing passengers and for future generations of Metro travellers."
The specifications include:
With sections of the Metro being impenetrable to mobile internet signals, Wi-Fi will be a big benefit to passengers. Companies applying to build the new trains will be asked to incorporate it into the design.
2) Charging points
With all that extra time we can spend accessing the internet on board Metro once Wi-Fi arrives, we'll need some extra power for our devices too. Thankfully charging points will also be part of the new design.
3) Air conditioning?
We've all had uncomfortable journeys in the summer when the trains are busy and the sun in strong.
It's likely the new Metro carriages will come with air conditioning, though this hasn't yet been listed as a must for the new trains. The specifications state this will "be confirmed during formal market consultation".
4) Windows that won't open
Air conditioning would come with permanently closed windows, as the AC system wouldn't work properly otherwise.
Hopefully it will work well enough to avoid the lack of windows becoming a stuffy frustration.
5) 'Off-wire' capability to proof trains against power line problems
The notorious Metro suspensions and delays which have blighted the system in recent have often down to overhead power line faults - including thieves stealing the cables.
The new trains will include a back-up system which will allow them to run between stations without overhead lines, so passengers don’t get stuck between stops when a problem occurs.
6) Brakes which generate power
As with many modern new vehicles, the energy created when the new Metro trains brake will be captured and stored to help power the system (perhaps to provide the off-wire capability), making it more efficient.
7) Jumbo all-in-one carriages?
This is another maybe, but the new trains could have one long carriage rather than the two connected carriages with no connecting door that we have at present.
The report on the specifications for manufacturers states Nexus will be ordering 84 Metrocars or "similar capacity achieved with 42 trains, given that current trains normally operate as two Metrocars coupled together".
It will depend on proposals put forward by the winning manufacturer as to which style of Metro car we get.
8) Tube-style seating
This has already been in the headlines, with disagreements between passengers - and authorities - over which style of seating would best suit the new Metro trains.
This will make more room for passengers at rush hour, and for people carrying luggage.
There were concerns about this leading to fewer seats, and that the seating style was not suitable for the nature of Metro, from Sunderland City Council
9) More space and improved decor
The specs stipulate the trains must have "more space for luggage, buggies and wheelchairs" and a "modern-feeling internal decor".
10) Display screens
Once on board a Metro, passengers have relatively little information to hand on services.
The new trains will include electronic information screens and "real-time information" for passengers.
11) Improved CCTV
CCTV is already used on the Metro, but new systems will enhance coverage to improve security.
12) More destinations?
This is another big "if and when", but Nexus managing director Tobyn Hughes' words that the cars will be "future-proofed" to make them capable of serving "more destinations on a wider network in the future" certainly keeps the door wide open to extending the system to areas campaigners have dreamed of seeing served by Metro.
Washington, business and retail parks such as Doxford International and Rainton Bridge Business Park, a direct link between Sunderland and South Shields, and a route down the mothballed Leamside Line in the Houghton area have long been on the wishlist of politicians, transport groups and campaigners in the area.