Sanborn Maps

I’m involved with the Dixie Model Railroad Club here in Nashville and have an assignment to build the Tennessee Egg Company structure that sat along the railroad in Chattanooga, TN. Other than a few aerial images, the main document at hand to build this structure is a Sanborn Fire Insurance Map. These are very good resources of structures in communities served by railroads, many of them being commercial industries along the right of way. Click on any image here to review a larger size.

Above is a scan of the map portion available for the project. Sanborn maps are drawn to scale but this print out seemed to be from a digital file and not full size. How do I determine the scale of this plan? A clue lies in the roadways as many are marked as to the right of way width. In this case, West 17th Street has a 50-foot marking at the left near the railroad tracks.

These maps are full of information used by local firefighters. The map key above calls out many details useful for modeling, too. Original maps can be quite colorful as structures of different building materials would be noted by various colors on the maps.

Another hobby use for a Sanborn map is to create print outs reflecting a footprint in the scale you model. It takes a little math and some Photoshoppery, but the scan was enlarged to full HO scale size. From this image, a full size footprint was printed to see how it would fit on site.

Here’s the enlarged Sanborn map scan on site at the Dixie Club layout. It is a large structure, three feet long and a couple feet deep. Several sheets of the print outs were taped together. Once these were positioned to line up on the proposed track siding, we found the building was a bit too long. Note in the image above how the footprint extends over a track at the upper right that is already in place. Fortunately, this is a loading dock and can be compressed a bit.

The next step is to make a mock up of the Tennessee Egg structure using data from the Sanborn map. In the image above, green circles call out numbers for the height of the structure from the ground to the top of the walls. The blue circles call out digits for the number of floors of the structure. This data is used by firefighters so they can battle disaster.

The main brick portions of the three-story building are all at 40-foot height, while the dock is noted as 14-foot height. There are a couple of fire walls in the building and these affect the roof appearance. The mock up was built using a long straightedge and a utility knife to cut spare cardboard to height and length. Scrap wood was used to reinforce corners and carpenters glue holds it together. The dock is a separate structure with cardboard triangles reinforcing inside corners. Walls were painted with rattle cans. The mock up was built in a few hours outside on a sunny afternoon.

Here is the mock up in place on the Dixie Club layout. A few adjustments need to be made on the dock length and chipboard roofs will be installed so this can be used while a model is built.

Not all buildings are this size. In many cases, we work with smaller structures for our layouts. Using resized portions of Sanborn maps as footprints assists our understanding of relationships between structures and the railroad we model. The footprints can be used to determine placement and compression decisions. Data from the maps can be used to create mock ups as place holders for finished models.

Many Sanborn Fire Insurance Maps are available to view as digital files. Here are a couple of websites to explore. Feel free to add more sites and links in the comments section.

Check with your local librarian about access details for the area of your interest. Some states offer access through membership in a local library system. It is worth the visit or a phone call to find out more.

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5 thoughts on “Sanborn Maps”

  1. Here are a couple links:

    Dartmouth College NH Sanborn Maps:

    Sanborn Map key at the LOC, full color and very useful when you dive into these:

    My page of Suncook Valley RR Sanborn Maps:

    FWIW, these maps were NOT for firefighters. The Sanborn Map company had a near-monopoly on producing these maps which were made available (for profit, of course,) to fire insurance companies so they could better price their policies based on the facts on the ground. As such, they were trusted sources of information on their subject matter, but don’t put too much stock on things such as yard track arrangements.

    I did some extensive research using these for a Cornell prof (for his personal, not academic, use) back in the early 90’s. I swapped my hours of labor in the stacks and over a microfiche machine for an … HO Bachmann 44-tonner. Hah!

    1. Thank you for the links and extra info, Earl! I agree that the maps were created for insurance purposes. Is your 44-tonner still in service? – Eric

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