 The line ran between Hereson Road , across the road from Dumpton Park station , down a steep gradient of 1 in 15 in the new tunnel , before running at a 1 in 75 gradient down the original tunnel to the lower terminus . The line consisted of a single line , branching into two platform tracks at the two stations , with a crossing loop halfway along the tunnel . Over the 1 @,@ 444 @-@ yard ( 1 @,@ 320 m ) journey between Hereson Road and the lower terminus , the line descended 83 feet ( 25 m ) . 
