Speaking about the £10,000 tapping survey being undertaken on the Rhondda Tunnel, local Assembly Member Leanne Wood said: "It is great that this survey - secured as a result of Plaid Cymru's budget negotiations with the Welsh Government - will take us one step closer to the reopening of the Rhondda Tunnel.
"I, along with every other member of the Rhondda Tunnel Society and its many champions, eagerly await the findings of the survey and hope that it will be positive."
She added: "This project has the potential to be transformative for both the Rhondda and the Afan valleys. This is why the Labour Cabinet needs to stop their stalling and assume ownership of the tunnel. Until they do this, all attempts to take this project to the next stage will be hampered.
"It is a source of ongoing frustration that we have a Welsh Government that is ten steps behind the ambition and energy of the Rhondda Tunnel Society."