Christopher Brimley updated October 13, 2011

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  • Modeling Streets and Roads Part 3A - Asphalt

    by Doug Geiger, MMR

    Photos by the author

    A heavily-repaired asphalt road is shown in this photograph. Repairs are usually done by spreading liquid tar to fill any cracks in the roadway. Note how much darker the surface is where the vehicles travel. The pavement markings have been freshly applied.
    Model Railroading - July 2002 - Page 48

    This next part of the Streets and Roads series concentrates on modeling asphalt roads. Many city streets are constructed from asphalt. Two methods of modeling an asphalt highway are presented, one this month, and another next month. Both use commercial products. Observation of a prototype road will ensure that the coloring is correct. Many model railroaders make asphalt roads much too dark. They should be a light gray, and never black. Asphalt roads are somewhat difficult to make.

    This first method uses AMI Instant Roadbed. It is a tar-like product most commonly used under model railroad track. Since it is fairly thick, this method is best suited for the larger scales, although it can be used for HO. Curves can be formed by gently bending the material. Fine ballast is used to simulate the gravel in asphalt. Tar patches are also made using the same material as the roadway. A grade crossing is included in the sample highway. A gravel shoulder is also added to illustrate a combination of techniques can provide interest. The following sequence of photos illustrate these techniques.

    We begin by preparing the site for the asphalt road. An angled grade crossing is included and a gravel shoulder is to be applied to one side of the highway.

    The roadway has been elevated above the surrounding scenery by using a piece of Homasote. This matches the track height. Sculptamold is used to form the ballast shoulder for the railway and to blend the highway into the scenery.

    Model Railroading - July 2002 - Page 49

    AMI Instant Roadbed is used to form the highway surface. It is available in three widths: 1", 2" and 3" by 30' rolls. It is a tar-like substance, 1/8" in thickness and coated on both sides with adhesive.

    For a two-lane HO-scale highway, press two strips of Instant Roadbed side-by-side. Push the material directly over the track to mark the grade crossing.

    Cut the material using a new X-Acto #11 blade. Using scissors is not recommended due to the flexibility and stickiness of the product.

    After cutting a piece of Instant Roadbed to fit, press it in place. Then remove the paper backing which exposes more adhesive.

    Using a linoleum roller, firmly press the material into the sub-grade. Using the paper backing will keep the roller from pulling up the surface.

    Use gap-filling cyanoacrylate (CA) glue to keep the edges of the Instant Roadbed firmly attached to the scenery. A bead of CA cement can also be run into any cracks between sheets, such as in the center of this highway sample.

    Next, sprinkle a fine-grained light gray ballast onto the roadway surface. N-scale ballast works well for HO-scale.

    Use a soft brush to lightly spread out the ballast. This rock should be evenly scattered over the surface of the Instant Roadbed material.

    Model Railroading - July 2002 - Page 50

    Using scrap pieces of the backing paper and the linoleum roller, press the ballast into the roadway surface. It will be difficult to remove any ballast after this step, so be careful not to move the grains around too much.

    The pavement stripes are added by masking the surface with drafting tape and then stipple painting with a stiff brush. By varying the amount of paint on the brush, you can simulate the newness of the stripes. Note the finished white strip along the top edge of the highway.

    Simulate tar repairs by teasing out small bits of extra Instant Roadbed material and applying them with a tweezers onto the roadway surface. Since these seams will be somewhat thick, this step looks better in the larger scales.

    Again, press any tar pieces into the surface with some scrap backing paper and the roller.

    Another method of adding tar repair seams is by using a Sharpie marking pen. By varying the amount of cracks, one can make a road overdue for repair or be brand new.

    Powdered chalks are brushed along the traffic lanes to simulate wear patterns. Since the Instant Roadbed material is porous, the chalk will remain where it is placed. However, it will be difficult to remove chalk, so light applications are recommended.

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2 comments
  • kevin thomas likes this
  • Rick Phipps
    Rick Phipps Christopher. I am really enjoying these articles. I am printing these out to use as I begin to do my roads. I hadn't planned on dirt roads but after seeing that other article I have decided I have to have some. Thank you for posting.
    October 13, 2011
  • Christopher Brimley
    Christopher Brimley Thanks Rick, there are two more that I will be posting, but there are one or two that wont be posted because the issues are currently missing.
    October 13, 2011 - 1 likes this