maybe old news,but anyone wishing to visit the quarry from gilfach ddu/slate museum must be prepared for a detour-ther has been some subsidence on the embankment,and the A1 incline drum house roof has apparently collapsed(see last photo to dinorwig user album).as a result,you have to go around the west side of Vivian (country park incline route) that will bring you out by the Anglesey Barracks.
Of course,you could always you the Allt Ddu car park near Dinorwig village....
..... Or try and drive up in a frontera!check out bbc news(wales) someone decided to take ther 4x4 up Snowdon,as one of the "things to do before you die".now going to Caernarvon crown court for his attempt and the car is still stuck up there!