When doing the layout work for putting “paved” roads around (and/or over) tracks, I tape a large piece of paper over the area, then add marks and notes for reference points where the paper is attached - this allows it to be taken off and then place correctly back in its exact original position, whenever needed.
To accurately indicate the position of tracks, I use a pencil, laying it almost horizontal with the “ground”, with the lead portion against the outer top-edge of the rail.
I then repeat this for the inside edges of the rails if that area is to be “paved” too.
The paper can then be cut along the sharpest side of the pencil lines, then taped in placed on the sheet styrene, so that the pattern can then be drawn directly on the plastic.
For the pieces which go between the rails, whether they’re road crossings or portions of paved areas with tracks, the between-the-rails areas need to be narrower than the rubbed pencil lines indicate, to leave room for the wheel flanges of locomotives and rolling stock.
On the crossings shown in the photos, those pieces fit in the space between the moulded-on spike heads of Atlas code 83 track and turnouts. That width is .528".
If those crossings were blown up to full size, the .060" thick styrene between the rails is .023" lower than the railheads…roughly the equivalent of 2", as bad or worse than some real crossings.
I suppose that I could have used .080" sheet styrene for those areas, but the LPDs (Little Plastic Drivers) haven’t yet complained.
The .060" thick sheets are almost perfect for the pavement outside the rails, though, as they sit atop the moulded-on spikeheads. This places that pavement .013" below the railhead, which means that if you’re manually cleaning track (I seldom do, except after ballasting or adding track-side ground cover, using a very fine abrasive pad, meant for cleaning electrical contac