When you say traffic signal design, what exactly do you mean? I could point you to a few sources for good cadd standards for intersection drafting or layout, but if you are looking for something to help you with signal timing and that wort of thing, you're going to have to look for a different program such as Synchro or Transyt 7-F
Most State DOT's have CADD standards relating to signal design (IE line wieghts, traffic cells, line codes, etc.) Tennessee DOT has theirs online for downloading. I have found it to be a very good one to use if lacking information. It might be a good place to start.
The Institute of Transportation Engineers (ITE) also has a publication called the Manual of Traffic Signal Design, which has a chapter on contract document layout. While this doesn't adress specific CAD issues, it does give a good overview of what information needs to be included on the various plan and detail sheets. It's available at the ITE website (
I agree with Megan that the best place for specific CAD standards such as line weights and appropriate cells is your local state department of transportation, most of whom have their standards published on the web. If you're outside of the states, these standards can make a good starting point.
Hope this helps. Robert Weber, EI
Maurer-Stutz, Inc