NS, not sure how express lines would work because there would be non-express trains in front blocking the express train. Or do you mean trains that simply skip over stations and the next train does stop at that recently missed station. If so, don’t see the advantage. Just asking for clarification. And, if your idea would work, you can be sure Metro wouldn’t’ use it. :-)
dezlboy – NS is talking about express LINES, not trains. He’s mentioned before how he thinks Metro should have constructed two sets of tracks in each direction for every Metro line so we can run dedicated express lines like in NYC. This, coming from the guy who complains the most about unnecessary spending.