Just done the Clinchfield SD40 Tutorial and have a couple of points. Why are you told to sit in the drivers seat then have to go to the fuse box behind you. Only accessible if you are standing? On pulling away you are told to get to 10mph. The first few yards you go over the turn table where as far as I can see there is no speed limit! I would assume you have to crawl across the turntable?? All I get is a red triangle alert to the left of the speed. What does that indicate? Just notes and thanks for any info on the red triangle.
The red triangle on the HUD appears when you are speeding. The turntable may have a very low speed limit then. The sitting in the chair thing is usually the way TSW activates the physics of the train. It's how it knows which train is active. That might be the reason why you have to sit before doing other stuff.
Something weird happens with the speed limit over the turntable. The speed limit pip on the HUD goes to 100mph as you roll onto it, and the bar for your actual speed turns red to indicate overspeed, and you get the triangle. Clearly something not right, so all I would say is, ignore it.
There is no "allowed" speed for entering or leaving a turntable: the speedo will turn red if you're doing 0.1 mph. Ignore it.
In real life, the speed limit on a turntable can be 5 to 10mph depending on the turntable, but it is almost never more than 10mph