A new railway line crossing ramp found under Decor / Misc. Decor, costs 0.
Because of it's complexity in the previous setup of the rail crossing the road, I created a ramp to be placed over the road. In real life I've driven over such ramps. This makes it much easier as you can lay the tracks flat, the road doesn't have to be raised, basically all you have to do is align it to the 2 corresponding co-ordinates of the rail and it fits nicely over the whole road. The ramp is the same width as the road.
You need Ambitions and to place the package in both the mods/packages (Sims3 ) directory and in the "The Sims 3 Create a World Tool/ Packages" directory for the item to show in your game. There is an earlier post explaining how to install items in CAW.
Importing packages into CAW