Limon CO

(Created 2003; field-checked 2003; images below created after 2005 update)

This is not a big town, but it sure required a lot of effort to map it! USGS DLG's were not available. The linework from CDoT's GIS was not of acceptable quality. The printed topos were pre-interstate, and they showed a couple old highway junctions that had long since been reconfigured. So I tried another method: aerial photography. Using both the scanned topos and aerial photos available from Terraserver to create a hybrid image in Photoshop, it was a simple matter to register the photos to my basemap, and then to draw in the newer roads. Then, of course, I thoroughly field-checked the entire town. That allowed me to differentiate between streets and alleys, and to show features such as one-way roads, recreational trails, and footbridges.

The aerial photo method was also gratifying to me on a personal note, since I'm interested in historic highways: at the right side of the map below, see how I-70 is bifurcated (the eastbound and westbound lanes are separated and not parallel)? That was not done for topographic reasons (as I discovered when laying the old topos over the newer photos). Rather, it's because the westbound lanes were built on the roadbed for old US route 24 (presumably for economic reasons). However, the eastbound lanes required new construction, so they were also built as economically as possible: on a straight line.