Thought I'd share this as I googled it and saw a few posts saying Railclone doesn't support junctions. I thought of this idea, using ShapeBooleans and references to create an are from a couple of base splines. The process is broadly this:
Draw base splines for centre of road paths
reference copy these, add a spline offset modifier (double sided, don't keep original, closed end to create a closed shape) to them and union them in a Shape Boolean. Add a spline chamfer modifier to round off the corners. This forms the base object for an Array2S extended to clipping area for the road surface
Instance copy the original base splines and add them to another Shape boolean, this forms the baseline for a Linear array for the centre line for the road
Another linear array is made using the offset spline for the kerb/pavement
I haven't managed to work out a way to get the stop lines to cross the junction proerly when it's off adjacent, possibly just a broken line running all around the central road, hidden in places by the kerb.