This product is simple to assemble and easily adjusts to fit your layout. This is extremely important. Each layout is different--each layout has its problems with true level and true perpendicular. It took only 30 minutes for me to adjust the piers to fit my layout perfectly without adjustments to the layout itself. If your span is less than 150 n-scale feet, (mine was 130') this can easily be overcome with slight overlaps on the road at either end. I have also used this product in HO scale to connect an elevated mountain road to the world outside my layout. I highly recommend it.