Looks to me like WG are moving toward some form of Light Rail for some of the valley lines...
Metro documents on WG website suggest they want the franchise bidders to innovate and propose solutions that best fit the outputs WG will set out in the procurement process? Quotes from the published Metro brochures...
"The Welsh Government is committed to delivering best value for the taxpayer by incentivising the market to innovate in its choice of routes, services and technologies. The network will be future-proofed so that it can be expanded in future.
We are considering a number of different modes, including traditional heavy rail (diesel and/or electric), light rail and bus rapid transit .
We have appraised the options, but it will be up to the market to propose the solution that best satisfies our objectives"
"Light rail offers a number of unique features in urban and suburban transport. Light rail vehicles (or trams) can carry large numbers of people (200-400) and move easily, either on traditional railway track or on rails placed in streets."
"Because of their very fast and frequent services, light rail systems can experience dramatic increases in patronage. Such networks can then be extended more easily and affordably. This is the model so successfully applied in Manchester over the last 25 years with its regional Metrolink light rail network.
A light rail solution could form the basis of an extendable network. In fact, without it, given the constraints of the current heavy rail network, it would be very difficult to extend the rail network to support the urban expansion of Cardiff to the north west and into Rhondda Cynon Taf, or provide new/additional services to places like Nelson, Hirwaun, Heath Hospital and Crwys Road.
However, this analysis will not prejudice the procurement process, which may result in alternative innovations to meet our requirements."