If you're interested in seeing photos of the Atherton line in steam days (in all its four-track glory), take a look at the W.D Cooper gallery on-line at:
http://www.cooperline.com/wd_index.asp
The site is easy enough to use via the search boxes:-
Engine year: leave blank
Engine class: All
Year: Any
Location: Use drop-down menu to find locations such as Daisy Hill, Dobbs Brow, Walkden Troughs, Pendlebury Bank etc.
Then click on green "Search" button.
As a native of Patricroft & Swinton, quite a lot of Wilfred Cooper's photographs were taken along the Atherton line in the 1950s & 60s. Some of these images have been published elsewhere - a lot of them I'd never seen before.
It sounds like the line used to be very interesting from the trainspotters point of view. Very much the opposite to today. When did the line lose its express trains? ......
There certainly was more variety of traffic in the past, but as mentioned, this very much petered out by 1968.
1968 was the year most regular Liverpool Exchange - Man Vic - Bradford/Leeds DMU expresses were withdrawn, along with the last Manchester - Blackpool residential expresses routed via Atherton and the Dobbs Brow - Blackrod line.
At the end of summer 1968, two timetabled loco-hauled Summer Saturday workings also finished - one from Morley Low via Huddersfield & Stalybridge to Blackpool N., another from Leicester London Rd via Chinley to Blackpool N. Both trains used the Atherton - Dobbs Brow - Blackrod route, and no doubt there were other one-off loco-hauled excursions & specials to Blackpool/Morecambe etc using this cut-off before it finally closed in September 1968.
From July 1969, the Atherton line only usually saw DMUs to/from Wigan Wallgate and Southport, except for one return summer Saturday DMU which started at Pendleton Broad St, called at all stations as far as Daisy Hill, then via DeTrafford Jn, Whelley line & Standish Jn to Blackpool N. The through train between local stations & Blackpool ended at the end of summer 1971, just before the Whelley line closed.
During the 1970s there were still a few expresses along the line to/from Southport - daily fast commuter trains (stopping only at Southport, Meols Cop, Wigan W., Salford) & Man Vic), plus a few limited-stop trains timed for Manchester - Southport bucket & spade day trippers (although a lot of these ran via Bolton).