In this video, modeler Martin Tarnrot demonstrates how he models asphalt roads for model railroad layouts. Though modeling asphalt may seem simple, with the right technique, it can elevate a railroad to the next level. The base Martin uses for his diorama is a two inch thick styrofoam. The actual road is made from a very thin sheet of styrofoam.
The type of sheeting Martin uses is typically used under wooden floors, so can easily be found at a DIY store. If this material can’t be found, quarter inch plywood works well. He begins by cutting the foam sheet to the width of his road, about three inches and then applies PVA glue and spreads it over the surface using a piece of scrap wood. To fill the tiny crevices and holes in the foam, the surface needs to be plastered. For this application, Martin uses an indoor wall plaster and smoothes it out over the entire surface. After drying for a few hours, he sands the surface smooth.
For the cracks one typically sees in the surface of asphalt, Martin creates cuts with an X-acto blade. The roadside and the cracks will be painted in a dark brown color, which is a mix of black and burnt umber. He applies a thinned down layer of this paint, with 9 parts water and 1 part isopropyl alcohol. Once applied to the roadside, he wipes off the access with a paper cloth. The asphalt paint is then rolled on with a moderate amount of paint and light force. Martin goes on to demonstrate finishing touches.