The State marks all SR's on signs at intersections and bridges, and usually points in between. I've never been able to figure out what the other numbers on the signs mean, or the distance between them.
As for the T routes they are unfortunately getting a bit more problematic, in the last few years I've noticed a lot more roads with names on them and not the T#. To me this is idiotic, since all the maps show the T#. The problem though is that not all roads are marked anyway, it was getting better all the time, but now it seems we have this wild card. People can't find their way around in the more rural areas I guess because they are used to having road with names. I say let natural selection do what it is supposed to do.
As an example The road that runs along Germania Branch in Potter Cty. is t-433. To get there you drive into Germania on SR 0144 and turn on T 433. I mention this particular road because the first time I went there was back in Nov. 94. Germania Branch is in Landis' book and I wanted to check it out on the way home from a job in Olean Ny. The map said it was up on a hill out of town, or that is the way I read it, and I drove around up there for about an hour before I found it. T 433 is interesting, there is a place there called watering basin hollow, where at the side of the road there is a rock that is the shape of a watering basin. The road is called Rauch Rd. on the Penn Dot map, as far as I know the signs don't indcate that it is the sign has the T#.
Anyway the first time I drove down the road I went to take a look at the stream, and it flows mostly away from the road. At one point it comes out to the road and makes a hard turn at the road where it forms a huge pool and there in the pool was a pair of trout laying side by side getting ready to spawn. I didn't fish there that day but made a note of it and returned in the spring to fish. It is now part of the Brook Trout Enhancement Program as a headwater stream to Kettle Creek. I've been back every couple of years since to fish the area.
BTW, I tried entering the T# on Topo Zone and it didn't find it, I guess they don't take their online map to that level. Maybe they do if you sign up for the enhancement. If you would like more information on how I use the Delrome maps send me a pm, I don't want to bore anyone with more stories.