Many thanks Ian you have cleared up a long time mystery to me as no one up to now seemed to know much if anything about this layout .
Do you know if the bi directional running would have been connected with the Tonsley line connection which would have been at the same time .
I could see where both the cross over from the city would have commenced just before and after Emerson , but cannot see where the reverse would have been on the down line , I think the cross overs at Edwardstown were still in place, the next place would have been where the Tonsley line joined the up line ,and the third place would have been at Oaklands where there was also cross overs.
The reverse of this on any up trains would have been at Hallett Cove, Oaklands, Edwardston, and finally at the Emerson /Clarence park .
It would be interesting to confirm if this Idea actually was serious or just another good Idea that just got to hard at the time . The Sydney Lithgow line has many cross overs and I have been on trains from Katoomba that ran down on up lines and visa versa many times especially on Sunday services when track work was in progress .
As mentioned I have used this line from a small child , when single line running was in use and how Edwardstown was a crossover for many services . We got to know the crews very well . These were the days of the majic of railways and innocence .