Thanks for contacting us with this interesting use for RailClone. Unfortunately, at present there isn't a generator that will allow you to array segments between two splines, which would be ideal for a bridge like this. We are looking into this as a new feature for a future release, but there are many technical challenges we must resolve first.
There may be a workaround that involves using some trigonometry to rotate and scale cables to point towards supports. This technique uses a linear array but it's not a simple setup and there are a few restrictions that may limit its usefulness. Nonetheless, in case it is of some help. I've attached a sample style to this post so you can examine it in detail (the style uses the most recent RailClone beta).
Here's a short video to illustrate the style being used:
To apply this style you need to set the spline up in particular way. The flat sections, without cables, should be given a material ID of 2. Sections of splines with cables and supports take a material ID of 1. Vertex types should be set to corner except where you want to place a support column, for these a smooth vertex should be used.
I've added some annotations to the attached file to try to explain a little how it works, If you have any further questions, please let me know.