Yn ystod y cam nesaf, bydd angen gwneud rhagor o waith datblygu, a mireinio ac asesu'r pecynnau a nodwyd yn yr Achos Dros Fuddsoddi megis moderneiddio Prif Reilffordd y Gogledd o Gaergybi i Crewe gan gynnwys gwella cyflymder trenau, integreiddio â HS2 yn Crewe, darparu mwy o drenau, gwasanaethau parcio a theithio a bysys mewn sawl gorsaf ar hyd rheilffordd Wrecsam-Glannau Mersi.
The next step is further development, refinement and assessment of the packages identified in the Case for Investment such as the modernisation of the North Wales Main Line from Holyhead to Crewe including line speed improvements, integration with HS2 at Crewe, increased frequencies, and park & ride and bus integration at several stations along the Wrexham-Merseyside borderlands line.