Stevie D wrote:
I was thinking that 3-aspect signals would be great, with 'caution' meaning exactly as it does on real rails, and slowing the train down, but I don't know that this is a good idea - although it sounds great, I'm not sure how it would be of use.
It would be extremely useful for one of the two reasons why it is useful in the real world.
The first reason these are useful in the real world, is because a train moving at full speed takes a long time to stop, so if it's going top speed and comes upon a red signal, it may very well not be able to stop in time. So you have the distant, or caution signal, to make sure that you're NOT going at full speed if there's a possibility of coming upon a red signal. That's not really relevant to TTD, since the trains have the ability to stop on a dime no matter how heavy.
But the other reason is still very much relevant. Consider a very heavily trafficked piece of line, where the trains are stacked up behind each other. or there are faster ones stuck behind a slow on for a while. The slow one, of course, will move smoothly. But the fast ones will be going at full speed... then come to a full stop at the signal until the slow train clears the next block... then full speed again... only to stop at the next signal again. And so on down the line. Now, in the real world this is inefficient on fuel, but it's also inefficient as to travel time, because of the time it takes to accelerate from a full stop.
If, however, the signal prior to the red signal were at yellow, the fast train would be running at half-speed the whole time, nice and smoothly, without ever needing to come to a complete stop (since it wouldn't catch up to the slow train quite so quickly). This makes the whole line look both more realistic, and actually increases the throughput. Very realistic, and most helpful too in the artificially small TTD world.