Change (∆) in Direction

Change in Direction (also written ∆ Direction) is simply a measure of how much the element or figure changes the train's direction of travel from entry to exit. It is represented as a number in degrees from 0° to 180°, and is an absolute measure (meaning that movement n° to the left or right yield the same ∆ Direction). ∆ Direction only represents horizontal movement, and it is extremely easy to calculate, at least approximately.

The direction you are traveling in when you enter the figure or element is 0°, and if you are traveling in the same direction when you leave, it's a ∆ Direction of 0°. (Think vertical loop. If the loop wasn't there, it would be a straight piece of track.) If the figure turns you all the way around, like a Cobra Roll, now you're talking 180°. (If the Cobra Roll wasn't there, you'd need to make a U-turn to get back on track.) A 90° turn right or left is, well, 90°. And so on.


Example 1.2
The vertical loop (pink), as stated above has a ∆ Direction of 0° because you exit in the same direction you entered. The Inside Raven Turn (teal) turns you completely around so it's ∆ Direction is 180°. The orange curved track element turns you about a ∆ Direction of 45°, and the blue one has a ∆ Direction of 90°

It takes a little bit of abstract thinking, sure, but understanding ∆ Direction is necessary to understanding Mirror/Inverse, coming up below. Oooh, scary.