How... do I use splines for roads and such?

Ok, so im fairly new to ue4. Im trying to use the spline tool and ive watched a couple tut’s on how to make the blueprint but its not working and its like bunching the model up and not working the way it should be ex.

and how do I scale the railroad and or road to the actual dimesions it should be?

also how would I do [this][2]?

While this tutorial a bit old it still holds up quite well and is super well explained by Zak.

The movement itself you see in the video you provided as reference is done via "[Get Location at Distance Along Spline][1]". A "Distance" variable is simply increased over time and the object moves along the spline.