Runcorn East makes little sense as a turnback, with the current infrastructure you'd have to send the train past Acton Grange Junction to turn it back. At least Frodsham Junction isn't far past Frodsham.
If extension beyond Helsby were ever in the frame it would be worth adding a crossover from the Down to the Up Helsby so that Platform 1 at Warrington can be used to turn back trains from the south rather than just from the north.
Adding a chord from the Down Helsby to the Down Main where the lines cross at Keckwick would eliminate a flat junction conflict at Acton Grange too.
I think that we're far more likely to see 777s going to Warrington Central than Bank Quay in any case. Bank Quay would need ticket barriers, the fare evasion is bad enough as it is. For the foreseeable future, Helsby will be the limit of Merseyrail expansion in that area.
If extension beyond Helsby were ever in the frame it would be worth adding a crossover from the Down to the Up Helsby so that Platform 1 at Warrington can be used to turn back trains from the south rather than just from the north.
Adding a chord from the Down Helsby to the Down Main where the lines cross at Keckwick would eliminate a flat junction conflict at Acton Grange too.
I think that we're far more likely to see 777s going to Warrington Central than Bank Quay in any case. Bank Quay would need ticket barriers, the fare evasion is bad enough as it is. For the foreseeable future, Helsby will be the limit of Merseyrail expansion in that area.