I remember going through this old railway tunnel probably about 30 years. From memory we entered via a portal and cutting from near Pall Mall road north or Moorfields. It broke out through a deep cutting with loads of rubbish (and rats) opposite John Moors University on Byrom Street and then straight through to Wavertry/Edge Hill. Just stomping walking.
All was all in pretty good nick with some impressive straws in places. Being Liverpool at that time there was even a burnt out car half way through! Looking on Google maps I can not find the entrance we used, it looks like a car park may have been built over it, you can see the cutting opposite the Uni though.